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OPTICAL 
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Division of THE CHEMICAL RUBBER CO, 

Editor-in-Chief 
Robert C. Weast, Ph.D. 

Vice President, Research, Consolidated Gas Service Company, Inc. 



Coordinating Editor 
George L. Tuve, Sc.D. 



Editor-in-Chief, Mathematics 
Samuel M. Selby, Ph.D., Sc.D. 

Professor of Mathematics 
Hiram College 



Editor-in-Chief, Biosciences 
Irving Sunshine, Ph.D. 

Chief Toxicologist, Cuyahoga 

County Coroner's Office, Cleveland, Ohio 



HANDBOOK SERIES 



BIOCHEMISTRY 

Herbert A. Sober, Ph.D. 

National Institutes of Health 

BIOENGINEERING 

David G. Fleming, Ph.D. 

Case Western Reserve University 
Lester Goodman, Ph.D. 

National Institutes of Health 

CHROMATOGRAPHY 
Gunter Zweig, Ph.D. 

Syracuse University Research Corp. 

CLINICAL SCIENCES 

Willard R. Faulkner, Ph.D, 

Vanderbilt University Medical Center 
John W. King , M.D., Ph.D. 
Cleveland Clinic Foundation 

ELECTRO-OPTICS 

Robert J. Pressley,Ph.D. 

Holobeam Corp. 

ENGINEERING SCIENCES 
Ray E. Bolz, D.Eng. 

Case Western Reserve University 
George L. Tuve, Sc.D. 

THE Chemical Rubber CO. 

ENVIRONMENTAL SCIENCES 
Richard G. Bond, M.S., M.P.H. 

University of Minnesota 
Conrad P. Straub, Ph.D. 

University of Minnesota 



FOOD AND NUTRITION 
Nicolo Bellanca, Ph.D. 

CIBA-GEIGY Corp. 
Giovanni Fenaroli, Ph.D. 

University of Milano, Italy 
Thomas E. Furia 

CIBA-GEIGY Corp. 

MARINE SCIENCES 

F. G. Walton Smith, Ph.D. 

University of Miami 

MATERIALS SCIENCE 
C. T. Lynch, Ph.D. 

Wright-Patterson Air Force Base 

MATHEMATICS AND STATISTICS 
William H. Beyer, Ph.D. 

University of Akron 
Brian Girling, M.Sc, F.I.M.A. 

The City University, London 
Samuel M. Selby, Ph.D., Sc.D. 

Hiram College 

MICROBIOLOGY 
Allen I. Laskin, PhD. 

Esso Research and Engineering Co. 
Hubert Lechevalier, Ph.D. 

Rutgers University 

ORGANIC CHEMISTRY 
Saul Patai, Ph.D. 

Hebrew University of Jerusalem 
Zvi Rappoport, Ph.D. 

Hebrew University of Jerusalem 



RADIOLOGICAL SCIENCES 
Yen Wang. M.D., D.Sc. (Med.) 

University of Pittsburgh 

SPECTROSCOPY 
Jeanette Grassel !i 

Standard Oil Company (Ohio) 
James W. Robinson, Ph.D. 

Louisiana State University 



TOXICOLOGY 

Irving Sunshine, Ph.D. 

Cuyahoga County Coroner's Office, Ohio 



CRITICAL REVIEW JOURNALS 



ANALYTICAL CHEMISTRY 
Louis Meites, Ph.D. 

Clarkson College of Technology 

BIOCHEMISTRY 
Robert A. Harte 

American Society of 
Biological Chemists, Inc. 

BIOENGINEERING 

David G. Fleming, Ph.D. 

Case Western Reserve University 

CLINICAL SCIENCES 

Willard R. Faulkner, Ph.D. 

Vanderbilt University Medical Center 
John W. King, M.D., Ph.D. 
Cleveland Clinic Foundation 

ENVIRONMENTAL SCIENCES 
Richard G. Bond, M.S., M.P.H. 

University of Minnesota 
Conrad P. Straub, Ph.D. 

University of Minnesota 

FOOD AND NUTRITION 
Thomas E. Furia 
CIBA-GEIGY Corp. 



MACROMOLECULAR SCIENCE 
Eric Baer, Ph.D. 

Case Western Reserve University 
Phillip Geil, Ph.D. 

Case Western Reserve University 
Jack Koenig, Ph.D. 

Case Western Reserve University 

MICROBIOLOGY 
Allen I. Laskin, Ph.D. 

Esso Research and Engineering Co. 
Hubert Lechevalier, Ph.D. 

Rutgers University 

RADIOLOGICAL SCIENCES 
Yen Wang, M.D., D.Sc. (Med.) 

University of Pittsburgh 

SOLID STATE SCIENCES 
Richard W. Hoffman, Ph.D. 

Case Western Reserve University 
Donald E. Schuele, Ph.D. 

Bell Telephone Laboratories 

TOXICOLOGY 

Leon Goldberg, D.Phil., D.Sc. 

Albany Medical College of 
Union University 




HANDBOOK 

of 

LASERS 

with 

Selected Data on Optical Technology 



Editor 
ROBERT J. PRESSLEY, Ph.D. 

Manager of Research and Development 

Laser Products Division 

Holobeam, Inc. 



Published by 
THE CHEMICAL RUBBER CO. 

18901 Cranwood Parkway, Cleveland, Ohio 44128 



This book presents data obtained from authentic and highly regarded sources. 
Reprinted material is quoted with permission, and sources are indicated. A 
wide variety of references are listed. Every reasonable effort has been made to 
give reliable data and information, but the editor and the publisher cannot 
assume responsibility for the validity of all materials or for the consequences of 
their use. 



© 1971 by The Chemical Rubber Co. 

All Rights Reserved 

Library of Congress Card No. 72-163066 

Printed in the United States of America 



PREFACE 

The aim of this volume is to collect and present critically evaluated original data, both published 
and unpublished, that are relevant to laser research and development. The laser is close to its eleventh 
birthday. It has experienced a rapid growth, both in numbers and in complexity. Lasers of different 
types, frequencies, powers and energies have proliferated to such a degree that scientists are even be- 
coming specialized in restricted fields within the general field of lasers. 

The theory of the generation and control of coherent radiation is covered in various articles and 
texts. The experimental data, however, are being extended and enlarged much faster than the theory. 
To provide convenient access to this rapidly expanding volume of information is the goal of this hand- 
book. The textual material is, in general, only that necessary to explain the data. 

The data ar'e the results of many different experimental arrangements. There has been little stan- 
dardization between various laboratories in certain measurements such as threshold or efficiency. With 
this in mind, an important part of this handbook is the references to the original work, which should be 
consulted for details of how the various measurements were made. This referencing will become of less 
importance in later editions when there should be more standardization of measurement techniques. 

The listings of the laser transitions for this first edition represent data available in late summer of 
1970. There will undoubtedly be important additional data available between that date and the publica- 
tion date, but this is an inevitable consequence of publishing in a current field of research. 

The selection of data on related optical elements is not intended to be inclusive, but is meant to be a 
representative selection of some of the more useful items of considerable current interest. Both the 
American Institute of Physics and the Optical Society of America are currently preparing revised 
Handbooks, which will contain much more complete and detailed tabulations of topics covered periph- 
erally in this handbook. 

This handbook is intended for the use of active researchers in the field of lasers, and as such needs 
comments, criticisms and suggestions from these researchers if future editions are to be of maximum 
value. We welcome your cooperation in helping us to correct any errors or omissions. 

The advisors to this handbook have contributed considerable time and effort toward the compila- 
tion of the data presented. That this Handbook could appear at all is due to their unstinting co-operation 
in collecting, collating, evaluating and referencing the data, in addition to their continuing normal 
scientific responsibilities. 

I am personally indebted to both the David Sarnoff Research Center at Princeton, New Jersey, and 
Holobeam, Inc. at Paramus, New Jersey, for their cooperation during the compilation of this volume. 
I also wish to thank Mrs. Mary Lou Wu of the Chemical Rubber Company for her continuing en- 
thusiasm and technical expertise in the editing of the book. 

Hopewell, New Jersey RoBERT J - ^^s^ 

September 1, 1971 



VII 



ADVISORY BOARD 

EDITOR AND CHAIRMAN 

Robert J. Pressley, Ph.D. 

Manager of Research and Development 

Laser Products Division 

HoJobeam. Inc. 

Paramus, New Jersey 07652 

MEMBERS 



Juan J. A model, Ph.D. 

Member of Technical Staff 
RCA Laboratories 
Princeton, New Jersey 08540 

Donald E. Bode, Ph.D. 

Head, Physics 

Sanla Barbara Research Center 

Goleta, California 93017 

William B. Bridges, Ph.D. 

Senior Scientist 

Hughes Research Laboratories 

Malibu, California 90265 



Charles H. Church, Ph.D. 

Staff Specialist 

Laser Technology and Systems 
Advanced Research Projects Agency 
Arlington, Virginia 22209 

Thomas F. Deutsch, Ph.D. 

Principal Research Scientist 
Research Division 
Raytheon Company 
Waltham, Massachusetts 02154 



William Eppers, Jr., Ph.D. 

Senior Scientist 

Laser Technology Branch 

Air Force Avionics Laboratory 

Wright- Patterson Air Force Base 

Dayton, Ohio 45433 



Hans Jaffe, Ph.D. 

Vice President and Director 

Gould Laboratories/Electronic Technology 

Gould, Inc. 

Cleveland, Ohio 44108 



Fred M. Johnson, Ph.D. 

Professor and Chairman 
Department of Physics 
California State College 
Fullerton, California 92631 



Herwig Kogelnik, Dipl.-Ing., D. rechn., D. phil. 

Department Head, Coherent Optics Research 
Bell Telephone Laboratories 
Holmdel, New Jersey 07733 



Alexander Lempicki, Ph.D. 

Manager, Quantum Physics Group 
GTE Laboratories 
Bayside, New York 1 1 360 



Irving Liber man, Ph.D. 
Fellow Engineer 

Westinghouse Research Laboratories 
Pittsburgh, Pennsylvania 15235 



Jacques I. Pankove, Ph.D. 

Fellow, Technical Staff 
RCA Laboratories 
Princeton, New Jersey 08540 



Yon-Han Pao, Ph.D. 

Professor and Head of Division 
Electrical Sciences and Applied Physics 
Case Western Reserve University 
Cleveland, Ohio 44106 



Keith S. Pennington, Ph.D. 

Research Staff Member 

IBM Research Center 

Yorktown Heights, New York 10598 



viii 



Advisory Board 



Martin A. Pollack, Ph. D. (E.E.) 
Member of Technical Staff 
Bell Telephone Laboratories 
Holmdel, New Jersey 07733 



Marvin J. Weber, Ph.D. 

Principal Research Scientist 
Research Division 
Raytheon Company 
Waltham, Massachusetts 01778 



Colin S. Willett, Ph.D. 

Research Physicist 
Harry Diamond Laboratories 
Department of the Army 
Washington, D.C. 20438 



Richard F. Woodcock, Ph.D. 

Chief Research Physicist 
American Optical Corporation 
Southbridge, Massachusetts 01550 



IX 



CONTRIBUTORS, COLLABORATORS AND AUTHORS 



Juan J. Amodei, Ph.D. 

Member of Technical Staff 
RCA Laboratories 
Princeton, New Jersey 08540 



Hans Jaffe, Ph.D. 

Vice President and Director 

Gould Laboratories/Electronic Technology 

Gould, Inc. 

Cleveland, Ohio 44108 



Donald E. Bode, Ph.D. 

Head, Physics 

Santa Barbara Research Center 

Goleta, California 93017 



William B. Bridges, Ph.D. 

Senior Scientist 

Hughes Research Laboratories, Inc. 

Malibu, California 90265 



Di Chen, Ph.D. (E.E.) 

Staff Scientist 

Honeywell Corporate Research Center 

Hopkins, Minnesota 55343 



Arthur N. Chester, Ph.D. 

Head, Chemical Laser Section 
Hughes Research Laboratories, Inc. 
Malibu, California 90265 



A. M. Clarke, Ph.D. 

Associate Professor of Biophysics 
Medical College of Virginia 
Richmond, Virginia 23219 



Verne R. Costich, Ph.D. 

Manager, Optical Coating Department 

Coherent Radiation 

Palo Alto, California 94303 



Thomas F. Deutsch, Ph.D. 

Principal Research Scientist 
Research Division 
Raytheon Company 
Waltham, Massachusetts 02154 



William Eppers, Jr., Ph.D. 

Senior Scientist 

Laser Technology Branch 

Air Force Avionics Laboratory 

Wright-Patterson Air Force Base 

Dayton, Ohio 45433 



Fred M. Johnson, Ph.D. 

Professor and Chairman 
Department of Physics 
California State College 
Fullerton, California 92631 



Ivan P. Kaminow, Ph.D. 
Member of Technical Staff 
Bell Telephone Laboratories 
Holmdel, New Jersey 07733 



Herwig Kogelnik, Dipl.-Ing., D. techn., D. phil. 

Department Head, Coherent Optics Research 
Bell Telephone Laboratories 
Holmdel, New Jersey 07733 



Alexander Lempicki, Ph.D. 

Manager, Quantum Physics Group 

GTE Laboratories 

Bay side, New York 11360 



Tingye Li, Ph.D. 

Department Head 

Repeater Techniques Research Department 

Bell Telephone Laboratories 

Holmdel, New Jersey 07733 



Irving Li hi' r man, Ph.D. 
Fellow Engineer 

Westinghouse Research Laboratories 
Pittsburgh, Pennsylvania 15235 



Reuben S. Mezrich, Ph.D. 

Member of Technical Staff 
RCA Laboratories 
Princeton, New Jersey 08540 



Jacques I. Pankove, Ph.D. 

Fellow, Technical Staff 
RCA Laboratories 
Princeton, New Jersey 08540 



Contributors, Collaborators and Authors 



Keith S. Pennington, Ph.D. 

Research Staff Member 

IBM Research Center 

Yorktown Heights. New York 10598 



David L. Staebler, Ph.D. 

Member of Technical Staff 
RCA Laboratories 
Princeton, New Jersey 08540 



Douglas A. Pinnow, Ph.D. 

Supervisor, Solid State Effects 
Bell Telephone Laboratories 
Murray Hill, New Jersey 07974 



Martin A. Pollack, Ph.D. (E.E.) 

Member of Technical Staff 
Bell Telephone Laboratories 
Holmdel, New Jersey 07733 



Edward H. Turner, Ph.D. 

Member of Technical Staff 
Bell Telephone Laboratories 
Holmdel, New Jersey 07733 



Marvin J. Weber, Ph.D. 

Principal Research Scientist 
Research Division 
Raytheon Company 
Waltham, Massachusetts 01778 



Daniel L. Ross; Ph.D. 

Member of Technical Staff 
RCA Laboratories 
Princeton, New Jersey 08540 



CoUn S. Willett, Ph.D. 

Research Physicist 
Harry Diamond Laboratories 
Department of the Army 
Washington, D.C. 20438 



Singh, Ph.D. 

Member of Technical Staff 
Bell Telephone Laboratories 
Murray Hill, New Jersey 07974 



Richard F. Woodcock, Ph.D. 

Chief Research Physicist 
American Optical Corporation 
Southbridge, Massachusetts 01550 



XI 



TABLE OF CONTENTS 



1 OCULAR HAZARDS 

Definitions 

Permissible Exposure Levels 



2 INCOHERENT OPTICAL SOURCES 

Standards and Definitions 13 

Continuous Sources 14 

Pulsed Sources 30 

3 ATMOSPHERIC TRANSMISSION 

Introduction 39 

Broad-band Atmospheric Transmission Measurements 42 

Low Altitude Transmission Measurements 52 

High Resolution Solar Absorption Spectra from 10,000 ft 63 

High Resolution Solar Absorption Spectra from 40,000 ft 125 

Transmission Measurement near Important Laser Lines 146 

Underwater Transmission Measurements 1 52 

4 MULTILAYER DIELECTRIC COATINGS 

Antireflection Coatings 1 55 

High-reflection Coatings 156 

Beam Splitters 157 

High Pass Filters. ..-.., 159 

Low Pass Filters 160 

Band Pass Filters 1 60 

Laser Mirrors 163 

Performance and Ease of Fabrication Data on 14 Types of 

Dielectric Multilayer Coatings 169 

5 OPTICAL DETECTORS 

Characteristics of Photoemissive Surfaces 171 

Typical Photodetector Parameters 172 

6 NEUTRAL GAS LASERS 

Introduction 183 

Neutral Laser Transitions 1 86 

Specific Selective Excitation Mechanisms 219 

Characteristics of Important Neutral Gas Lasers 230 

7 IONIZED GAS LASERS 

Introduction 242 

Ionized Gas Laser Transitions 244 

Energy Level Diagrams for Ion Lasers 257 

Characteristics of Practical Ion Lasers 277 

xii 



Table of Contents 

8 MOLECULAR GAS LASERS 

Molecular Source Materials 298 

Diatomic Molecular Gas Lasers ■ ■ ■ ■ 306 

Triatomic Molecular Gas Lasers . . . . . 329 

Polyatomic Molecular Gas Lasers • • • 346 

9 DYE LASERS 

Summary of Dye Laser Properties ■• - 350 

Reported Dye Lasers • 351 

10 RARE EARTH LIQUID LASERS 

Chelate Lasers 355 

Aprotic Lasers 358 

11 COMMERCIAL LASER GLASSES 

Introduction 360 

Properties of Commercial Glass Lasers 362 

12 INJECTION LASERS 

Formulae and Definitions 365 

Spectral Range Covered by Semiconductor Lasers ■ 368 

13 INSULATING CRYSTAL LASERS 

Insulating Crystal Laser Hosts 371 

Iron Group Lasers 376 

Divalent Rare Earth Lasers 378 

Trivalent Rare Earth Lasers ■ 378 

Actinide Lasers . ■ 388 

Insulating Crystal Laser Wavelengths 389 

Sensitization Combinations of Insulating Crystal Lasers 392 

Continuous Wave Operating Insulating Crystal Lasers 393 

Absorption Spectra of Trivalent Ions in Yttrium Aluminum Garnet 398 

14 LASER BEAMS, MODES AND RESONATORS . 

Laser Beams 421 

Laser Resonators 428 

15 LINEAR ELECTROOPTIC MATERIALS 

Definitions • 447 

Electrooptical Matrices 449 

Tabulation of Electrooptic Coefficients . . 451 

16 MAGNETOOPTIC MATERIALS 

Definitions - 460 

Magnetooptic Properties of Ferromagnetic, Ferrimagnetic, and Antiferromagnetic 

Materials 461 

Magnetooptic Properties of Paramagnetic Materials 472 

Magnetooptic Properties of Glasses 473 

xiii 



Table of Contents 

17 ELASTOOPTIC MATERIALS 

Introduction and Definitions 478 

Strain-optic Tensor 479 

Photoelastic Coefficients , 481 

Selected Acousto-optic Materials 484 

18 NON-LINEAR OPTIC MATERIALS 

Introduction and Definitions 489 

Form of the Second Harmonic Generation Tensor 490 

Second Harmonic Generation Coefficients 497 

Refractive Indices of Selected SHG Materials 507 

19 STIMULATED RAMAN SCATTERING 

Introduction and Definitions 526 

Materials Exhibiting Stimulated Raman Scattering 527 

20 DIRECT OPTICAL STORAGE MEDIA 

Introduction and Definitions 533 

Electrooptic Recording Media 534 

Inorganic Photochromic Materials 535 

Organic Photochromic Materials 535 

Evaporated Thin Films 545 

21 HOLOGRAPHIC PARAMETERS AND RECORDING MATERIALS 

Introduction and Definitions 549 

Photoresists and Photopolymers 563 

Photochromies 568 

Characteristics of Silver Halide Photographic Emulsions 571 

Thermoplastic Recordings 586 

Magnetooptic Materials 588 

Free Radical Films 590 

TABULATION OF GAS LASERS BY WAVELENGTHS .595 

INDEX .619 



XIV 



Section I 

Laser Safety 



Ocular Hazards 



A. M. Clarke 

Department of Biophysics 

Medical College of Virginia 

Virginia Commonwealth University 

Richmond, Virginia 23219 



Ocular hazards in the vicinity of laser devices include not only the laser itself, but the optical pumps 
used for excitation, the off-axis spontaneous radiation from gas discharge tubes, and occasionally the 
blackbody radiation of absorbers used to stop extremely intense beams. Geometrical considerations 
make the latter two cases a lesser hazard, but obviously do not remove them from inclusion in a safety 
protocol. 

Ultraviolet devices of all types must be carefully controlled, as exposure of the cornea to even 
relatively low levels of irradiation at wavelengths less than 320 nm produces " sunburn " of the cornea, 
called " photophthalmia." Because a source in this region is not visible, has a cumulative effect, and the 
extremely dehabilitating " blepharospasm," or " sand in the eye " reaction to the corneal epithelium 
sloughing off and exposing the nerve tissue does not occur until 30 minutes to 24 hours following ex- 
posure (usually in the evening or night after exposure), any source which has a significant ultraviolet 
component must be used with caution. Figures 1-1 and 1-2, from the work of Pitts and his associates, 1 ' 2 
indicate the sensitivity of rabbits and primates to the ultraviolet. 

The middle infrared (10.6 /i) portion of the spectrum also affects the corneal epithelium as the 
primary damage site. In this spectral region the damage mechanism is of thermal origin, not abiotic 
as in the case of the ultraviolet. Thus, the damage mechanism is a function of the time-temperature 
history within a single exposure interval. The threshold for a minimal irreversible lesion on the cornea is 
given in Figure 1-3. 

o 



u 
O 

UJ 

ac 

(0 

o 

Q. 
X 

UJ 



O 

X 

<n 

0T 

X 

I- 
t 

GO 
00 

< 

or 




220 240 260 280 300 320 
WAVELENGTH IN NANOMETERS 



340 



Fig. 1-1 . Threshold exposure (Q c ) for the production of photophthalmia in rabbits versus 
wavelength of ultraviolet light. Each point on the curve is plotted at the peak wavelength of the 
various 10 nm wavebands. (From Pitts, D. G. and Kay, K. R., Amer.J. Optom., 46, 561, 1969.) 



Handbook of Lasers 



70 r 




220 240 260 280 300 

WAVELENGTH IN NANOMETERS 



320 



Fig. 1-2. A comparison of thresholds (Q c ) for the production of photophthalmia 
in rabbits and primates, as a function of wavelength. (From Pitts, D. G., et ah, SAM- 
TR-70-28, USAF School of Aerospace Medicine, Brooks A. F. Base, Texas, in press.) 



I0 3 r 



^ I0 ! 



10' 



10° - 



10" 



.4fc-VASSILIA0IS.tt.al. 
O-LEIBOWITZ and PEACOCK 
▼-GULLBERG.tt.ol. 
X- CAMPBELL, tt.ol. 
■-FINE.tl.al. 



<*b o 



I0' 3 



lO- 2 



10° 
EXPOSURE TIME 



I0 1 
(sec ) 



I0 2 



I0 3 



10" 



Fig. 1-3. Threshold C0 2 (10.6 /x) power levels for irreversible lesions on the cornea as a function of ex- 
posure time. Data taken from references 3 (Vassiliadis), 4 (Leibowitz), 5 (Gullberg), 6 (Campbell), and 7 (Fine). 



1 Ocular Hazards 5 

The wavelength interval covering the visible and near visible region (400 nm to 1500 nm) must be 
considered in terms of the spectral characteristics of the eye. The transmission of the ocular media is 
illustrated in Figure 1-4, and the absorption of the retinal pigment epithelium (PE) and choroid, as 
measured by Geeraets and Berry, 8 is shown in Figure 1-5. 

Some investigators 9 have considered laser devices operating in the 1.5-2.0 n interval as "eye safe," 
a factor demonstrated by Lund and his associates 10 as possibly correct. However, until further work has 
been done on the vitreous and lens effects in this wavelength region, neither the middle infrared 
surface exposure levels nor the visible wavelength threshold levels should be exceeded for human occu- 
pational exposure. 

Retinal damage has been observed in the visible and near visible wavelength interval by many 
observers. Figure 1-6 gives the Medical College of Virginia measured and calculated retinal irradiance 
for white light (Xenon arc) and ruby laser exposure necessary to cause an irreversible, minimal oph- 
thalmospopically visible lesion for an extended (10 fi to 800 n diameter) image on the retina. 11 ' 12 
Table 1-1 gives the data for the minimum image size, barely ophthalmoscopically visible lesion pro- 
duction by several sources from the Stanford Research Institute. 3 The results are in reasonable agree- 
ment. Table 1-2 is a summary of the reported values of argon and helium-neon laser-produced power 
entering the eye to cause a threshold lesion for various exposure durations and image diameters. 13 





PERCENT TRANSMISSION THROUGH OCULAR MEDIA 
























































































IOO 




*~Y 


h* 








*■»■• 


MWM 


r*"* 


?& 














MEAN VALUES 
.— = Rabbit 
■■■ = Human 
^^ = Monkey 




90 


V 


z 
















-^ 






* 


£*«- 
















■O 1 . 


oU 


11 




















= 1 




L 


1 


i 
\ 










( 


70 


~t — ^~~ 




















tt 


j 


r 


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i 


^ , 


r 




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50 1 






















\ 


y 






i 














40 — I 
























r 






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30 — i 






























§ 


% 


JL 


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20 — I 






























• 


(S.. 


* 




i 

X 




MB 


' ^ #1 


L_ 






























\. 


*? 


N 







400 500 600 700 



800 900 1000 1100 
WAVE LENGTH (nm) 



1200 1300 1400 1500 



Fig. 1-4. Percent transmission for light of equal intensity through the ocular media of human, monkey 
(rhesus), and rabbit eyes. (From Geeraets, W. J. and Berry, E. R., Amer. J. Ophthal., 66, 15, 1968.) 



6 Handbook of Lasers 



100 

90 

| 80 

| 70 

^ 60 
k. 
§ 50 

§40 
30 



20 



PERCENT ABSORPTION IN RETINAL PIGMENT EPITHELIUM 

AND CHOROID 

GEERAETS and (ERRY 
































1 1 1 1 








































MEAN VALUES 
(Light of equal 
intensity and 
incident on the 
cornea ) 

— ■ Rabbit 
(Dutch~Chin- 
chi I la ) 

■■■ ■ Human 
■— * Monkey 




















































r 


VI 


.«> 


Ht-I 


I* F 






























































(i 


r\ 


1 


N 




\ 




























/? 






\ 


N 


N 










v 
























: 
is 












^ 


K 










i 


M 


















< 

1 

f 

f 

1 

1 


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N 








i 


— 


r 
































M 




\ 






















1 

f 

f 

_| 


I 


















1 


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L 


I*** 


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I 
f 

LA 


r 






















*fl 


CUJ 






»Wi«*ft«5 









400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 

WAVE LENGTH (nm) 

Fig. 1-5. Percent absorption of light of equal intensity at the cornea in the retinal pigment epithelium 
and choroid for rabbit, monkey, and man. (Redrawn to include correction for reflection from Figure 2 of 
Geeraets, W. J. and Berry, E. R., Amer. J. Ophthal, 66, 15, 1968.) 



• WHITE LIGHT 
Wavelengths <950m/j 

o LASER PULSES 

Wavelength 694.3 mju 

Image size 800 microns. 




-5 

10 



-3 

10 



-2 

10 



-I 
10 



10 10 10 10 10 10 10 10" 10 10" 10" 

TIME- SECONDS 
Fig. 1-6. Retinal power density necessary to cause minimal ophthalmoscopically observable lesions. (From 
Clarke, A. M., et al, Arch. Environ. Health, 18, 424, 1969.) Copyright 1969, American Medical Association. 



1 Ocular Hazards 



TABLE 1-1. STANFORD RESEARCH INSTITUTE 
THRESHOLDS FOR LASER EXPOSURE 3 





Exposure 
Duration 


Lowest Energy/Power 

Entering the Eye for 

Observed Damage 


Energy/Power 
Entering the 
Eye for 50% 
Probability 
for Damage 


Q-switched ruby 
(0.6943 fx) 


10t?s 


8.6 yd 


22 fjJ 


Long-pulsed ruby 
(0.6943 fi) 


200 jus 
1.7 ms 
1.7 ms 


0.48 mJ 
0.5 mJ 
0.42 mJ 


0.08 mJ 
1.1 mJ 
0.5 mJ 


Q-switched neodymium 
(1.06 p) 


30 77s 


1.60 /uJ 


280 /xJ 


Long-pulsed neodymium 
(1.06/*) 


600 /as 


3mJ 


4.7 mJ 


He-Ne gas 
(0.6328 fi) 


13.5 ms 
80 ms 


17 mW 
14 mW 


23 mW 
18 mW 



From Arch. Environ. Health, 20, 161, 1970. Copyright 1970, American Medical Association. 



TABLE 1-2. HELIUM-NEON AND ARGON LASER 
THRESHOLD VALUES 

POWER LEVEL (IN MILLIWATTS) FOR "THRESHOLD" LESION 



Image Diameter 
(microns) 


2 4 


10 


13.5 


20 


Exposure Duration {milliseconds) 
80 116 125 250 500 


1000 


2500 


3000 


10* 


Limiting Size 
He-Ne, Monkey 






23 
V 


40 
H 


18 
V 


18.8 23.6 
C H 


12.9 
H 


11.9 
H 


9.7 
H 








58 
He-Ne, Monk, H 








45.4 




25.1 


13.8 


11.9 


10.2 








70 
He-Ne, Monk, D 
























12.3 


100 
He-Ne, Rab, D 
























6.3 


105 
At, Mon, L'E 


74 71 


69 




36 


















115 
Ar, Rab, L'E 


72 
























149 
He-Ne, Monk, H 












56.1 


50.3 


39.8 


33.1 




30.6 




230 
He-Ne, Monk, H 
















66.2 


57.0 




44.2 


35.6 


250 
He-Ne, Rab, K 




















25 






260 
He-Ne, Rab, D 
























15.4 


800 
He-Ne, Rab, D 
























18.0 



C— Campbell, et a/. 14 
D — Davis and Mautner 15 



H— Ham,e/a/. 16 
K— Kotiaho 17 



L'E— L'Esperance and Kelly 18,19 
V — Vassiliadis, era/. 3 



8 Handbook of Lasers 

PERMISSIBLE EXPOSURE 

Safe values for chronic and acute exposure to the various optical sources have been proposed by the 
AMD, ACGIH, 21 the Air Force, 22 Army and Navy; 23 and the American National Standards Institute 
Z-136 Standards Committee on the "Safe Use of Lasers and Masers," is presently coordinating an 
effort of all laboratories and industrial groups to lay down useful, safe and unrestrictive guidelines for 
"maximum permissible exposure." 24 

The Department of the Army and Navy in TB MED 279/NAVMED P-5052-35 23 define the follow- 
ing "maximal exposure level(s) not expected to cause detectable bodily injury," measured at the cornea: 

Q-switched laser 1 x 10" 7 J/cm 2 

Non Q-switched laser 1 x 10 ~ 6 J/cm 2 

(1 ms duration) 

CW-laser (He-Ne/Ar) 1 x 10" 6 W/cm 2 

for all wavelengths between 0.4 \i and 1.5 \i. A "safety factor of 2 is recommended for use in field 
evaluation and training exercises," and "for long-term work with lasers, such as in the laboratory, a 
safety factor of 10 should be used." 

CO 2 (10.6 n) CW laser 100 mw/cm 2 

" Use of safety factors are not deemed necessary for the C0 2 CW laser." 

The Department of the Air Force, in AFM 161-8, 22 indicates considerably higher "permissible 
exposure levels" entering the eye: 

Ruby laser (Q-switched) 7.5 x 10" 6 J 

(non Q-switched) 1 x 10~ 4 J 

Nd laser (Q-switched) 45 x 10 " 6 J 

(non Q-switched) 5 x 10 ~ 4 J 

Helium-Neon and Argon laser 
(488, 515, 633 nm) 

less than 1 ms 20 mW 

1 ms to 10 ms 10 mW 

10 ms to 1 s 5 mW 

C0 2 laser 

less than 1 ms 8 W/cm 2 

10 ms to 50 ms 3 W/cm 2 

50 ms to 250 ms 1 W/cm 2 

To compare the Army/Navy "permissible levels" with those of the Air Force, using the most 
extreme condition of complete dark adaptation, a pupil diameter of 8 mm (area of 0.5 cm 2 ) must be 
used. 

Although the Air Force values are intended for battlefield conditions, and the Army/Navy values 
for peacetime service operations, the differences are quite marked. The ratio of the levels are for Air 
Force to Army/Navy: 

Q-switched laser 75 

Non Q-switched laser 200 

Argon/He-Ne CW laser 10 4 

C0 2 laser 10 

The envisioned environmental conditions during exposure should be considered when comparing the 
values, and the Air Force values are " permissible " under the conditions for which they are established, 
but should not be considered as " safe " for casual exposure of any type, or for levels of exposure for the 
general public except in times of emergency. 25 



1 Ocular Hazards 9 

The American Conference of Government Industrial Hygienists (ACGIH) endorses the following 
" safe" irradiance at the cornea for the worst case, or nighttime pupil diameter of 7 mm. 

Q-switched ruby laser 1 x 10" 8 J/cm 2 

Non Q-switched ruby laser 1 x 10" 7 J/cm 2 
Continuous wave exposure 1 x 10" 5 W/cm 2 

Again using the Army/Navy values for comparison, the ACGIH values are a factor of 10 more 

lenient in the CW case. 

The British Ministry of Aviation, 26 the Australian Department of Supply, 27 and other foreign and 
domestic government agencies have also established "safe" limits, but they are not included here. 

Sliney, 28 of the U.S. Army Environmental Hygiene Agency, who has been instrumental in con- 
version of certain damage values found by the various research groups to " safe " values for the Army 
and the ACGIH, has indicated that for practical application, the single " Army " values at the corneaare 

sufficient. 

To clear up the confusion immediately apparent to an uninitiated " safety officer attempting to 
apply the several values of laser " permissible exposure " levels, the ANSI Z-136 committee is working 
to provide a uniform, standard manner for specifying " safe and permissible " levels of exposure in both 
the near and far field, and in the extended image and limiting image cases. 

For UV sources, the American Medical Association Council on Physical Therapy recommends 
that for wavelengths less than 0.4 /*, the 8-hour working day irradiation level be held below 0.5 /i W/cm . 

For more detailed information, the reader should consult a recent review, 13 and the references. 



REFERENCES 

1 Pitts, D. G. and Kay, K. R., "The photo-ophthalmic threshold for the rabbit," Amer. J. Optom.,46, 561, 1969^ 

2 Pitts D. G., Bruce, W. R., Tredici, T. J., "A comparative study of the effects of ultraviolet on the eye, SAM-TR-70-28, 

3. SS^^S^Sc; Peppers, N. A., Peabody, R. R-, and Honey, R. C, "Thresholds of laser eye hazards," Arch. 

4. ?lZ\£t h M 2 X^^, G. R., "Corneal injury produced by CO, laser radiation," Report 787, U.S. Army Medical 
Research Laboratory, 1968. [AD 680 915, Clearinghouse, U.S. Dept. of Commerce Springfield, Va.]. 

5 Gullberg K Hartmann, B., Koch, E., and Tengroth, B., "Carbon dioxide hazards to the eye > Nature, 215 85V 1967 

6 Campbdi, C. Z RUtler, M. C, Bredemeier, H., and Wallace, R. A., "Ocular effects produced by experimental lasers, II: 

7. at! "^ ***y threshold to «*» dioxide laser irradiation '" Amer - J - 

8. 32X, W. j!, an 6 d 8 Berry, E. R., " Ocular spectral characteristics as related to hazard from lasers and other light sources," 

' Amer. j! Ophthal, 66, 15, 1968. , , nMQ 

9 Thornton G R " Safer wavelengths in the near infrared, Laser Focus, 5, is, l * w - ; + „u«j 

10 iuTo J. Landers M. B., Bresnick. G. H.. Powell, J. O., Chester, J. E., and Carver, C, Ocular hazards of the Q-switched 

11 SSw^E VwZf^^™^ Guerry, D., Clarke, A. M., and Geeraets, W. J., "Effects of laser radiation 

12. Sa*e,TX^^^^ -dMueller, H. A., " Laser effects on the eye," ArcH. Environ. 

13. Cllarkt; A.' ^'"Ocular hazards from lasers and other optical sources," CRC Critical Reviews in Environmental Control, 1, 

14. Campbell, C° J., Rittler, M. C, and Swope, C. H., " The ocular effects produced by experimental lasers, IV. The argon laser," 

15. dS T.^fll' MautnI;,W 9 L, "Helium-neon laser effects on the eye," Annual Report Contract No. DADA 17-69-C- 
9013 US Armv Med. Research and Development Command, Washington, D.C., 1969. „«,„.,. iU . ,, 

16. Ham, W T, GeeraSs, W. J., Mueller, H. A., WiUiams, R. C, Clarke, A. M., and Cleary, S. F., Retinal burn thresholds 
for the He-Ne laser in the rhesus monkey," Arch. Ophthal., 84, 191, 1970. 

17. KotSL A^Resnick? I .Newton, J., ana Schwell, H., "Temperature rise and photocoagulation of rabbit retinas exposed 
to the CW laser," Amer. J. Ophthal., 62, 644, 1966. . „ n^hthni 

18. I?Esperance, F. A., and Kelley, G. R., "The threshold of the retina to damage by argon laser radiation, Arch. Ophthal. 

19 L/Efpiancf'F. A., Jr., "An ophthalmic argon laser photocoagulation system: Design, construction, and laboratory inves- 

20. ^^^^^ Council on Physical Therapy, American Medical Association, 

21. "Thr a e 8 shold 4 lirnit values for physical agents, "American Council of Government Industrial Hygienists, Cincinnati, 1968, 
Suppl. 7 (published in Laser Focus, 4, 50, 1968). 

22. Department of the Air Force, AFM 161-8, "Laser health hazards control," Washington, D.C., 1 April 1969. 



10 Handbook of Lasers 

23 - SSSS^aS^S^F^^^ 279 ^ NAVMED ™*"'. "Control of hazards to health from laser 

24 ' ^ e ar C a a don Nati0nal StandardS InStitUtC ' ^^ St ™ d * rds Committee, "Safe use of lasers and masers," New York, in 

S' "fl'c"' E 'i and T ^ W J " Sen A A - R -' " The P hilos °P h y of a regulation," ^rcA. Environ. Health, 18, 416 1969 
?;• ..J?!?' ^stems-Code of Practice," British Ministry of Aviation, Shell Mex House, London 1965 

28' Simeon ??', ^T' M T°' *?' 1% De P artment of Supply, Commonwealth of Australia! 1966. 
zo. Mmey, L>. H., Evaluating hazards— and controlling them," Laser Focus, 5, 39, 1969. 



Section L 

Atmospheric Transmission, 
Sources, Filters and Detectors 



Page 

13 Incoherent Optical Sources 

39 Atmospheric Transmission 

155 Multilayer Dielectric Coatings 

171 Optical Detectors 



Incoherent Optical Sources 

I. Liberman 

Research and Development Center 

Westinghouse Electric Corporation 

Pittsburgh,, Pennsylvania 15235 

STANDARDS AND DEFINITIONS 

There are two major considerations in choosing lamps for optical pumping of lasers. They are the 
power density capable of dissipation by the lamp and the percentage of this power that is radiated at 
wavelengths that can excite the fluorescing active medium. For laser materials with short spontaneous 
emission lifetimes, the rate of increase of radiative power is important ; however this topic will not be 
considered in detail. 

All the information required can be obtained from a curve of the radiant emittance as a function of 
wavelength. The radiant emittance (W, watts/cm 2 ) is the radiated power through a unit area of the 
radiating medium, usually the wall area for a wall-stabilized gas discharge. Unfortunately the emittance 
is almost impossible to measure directly. The measurement that can be made most accurately is the 
radiance. The radiance (N, watts/cm 2 -ster) is the emittance divided by the solid angle that the measuring 
instrument subtends. Extrapolation from radiance to emittance can be made, if the arc is known to be 
either optically thin, i.e., radiance increases linearly with active path length, or optically thick, i.e., 
radiance independent of path length. However, most arcs used for pumping lasers are neither thick nor 
thin and have an optical thickness that varies with wavelength. Any extrapolation to emittance can have 
considerable error, since the measuring instrument collects a solid angle, which is typically between 0.1 % 
to 1 % of the total 2n ster radiated. 

Another commonly used measurement of lamp output is its irradiance. The irradiance (H, watts/cm 2 ) 
is the radiation intensity of the entire lamp incident on a unit area. The irradiance naturally decreases as 
the unit area is moved away from the lamp. The lamp can be considered a point source, if it radiates 
isotropically and if the lamp is more than two orders of magnitude smaller than its distance to the 
measuring point. Under these conditions, rarely met in practice, the irradiance decreases with the square 
of the distance to the lamp. Irradiance can also be measured by placing the lamp in an integrating sphere. 
The accuracy of this measurement depends on the size of the sphere and its spectral reflectivity. Radiation 
reflected from the sphere back to the lamp could affect both spectral and absolute efficiency. However, 
a similar situation exists when a lamp is placed in a laser pump cavity. In general, irradiance is a less 
useful measurement than radiance for evaluating lamps for lasers, since it is more difficult to approximate 
the emittance. This is because the measurement is usually not as accurate, since it is a strong function of 
size and shape of the lamp relative to the standard source. Also the calculation to emittance is difficult, 
since it depends on size and shape of the lamp as well as the assumption of square-law dependance for 
direct measurement. 

Up to now we have defined the units of radiation in relation to the radiant energy of all frequencies. 
We define the frequency of radiation as v. The wavelength X = c/v. The wave number n = v/c. Thus, 
for example, the spectral radiance can be defined as N„ watts/cm-ster, or N k watts/cm 2 -ster-nm or 
watts/cm 3 -ster, depending on the unit of wavelength used. 

Absolute spectral measurements of any type are difficult to obtain. This is particularly true for 
pulsed lamps. Most spectra published have arbitrary intensity scale and do not consider the spectral 
response of the measuring system, which usually varies considerably. Often, the spectral resolution of 
the instrument is a great deal poorer than the spectrum being measured. The resulting data give an 
accurate description of the energy within the resolution of the instrument, but can severely distort the 

13 



14 Handbook of Lasers 

spectrum if the spectrum is composed of intense but narrow lines. If the lamp is to be used to pump a 
laser having narrow absorption lines, then the overlap between lamp and absorber is completely undeter- 
mined. 

CONTINUOUS SOURCES 

Blackbody 

A rather complete set of blackbody tables is given in ref. 1. Tabulated is N x = C t X~ 5 [exp(C z /XT) — 
1] _1 watt cm -3 ster -1 over a wide range of X and T. The constants used are C t = 1.1909 x 10" 12 watt 
cm 2 ster -1 and C 2 = 1.4380 cm°K. Also tabulated are a number of CIE tables useful for visual and 
color standards. A convenient listing of W(X, T)lW m?OL (T) and Jo WdX/^Q WdXasa. function of AT in cm- 
deg is given in Table 2.1. 

Tungsten Incandescent Lamp 

The tungsten incandescent filament lamp has been calibrated by the National Bureau of Standards 
as a secondary standard of spectral radiance and irradiance. The spectral radiance standard consists of a 
flat strip filament and is calibrated with a graphite blackbody source in the wavelength region from 250 
nm to 2600 nm. 2 In order to preserve the life of the lamp as a standard source the calibration temperature 
used is no greater than 2470°K. 

The standard of spectral irradiance consists of a quartz-iodine lamp with a coiled-coil tungsten 
filament operating at about 3000°K and calibrated from 250 nm to 2600 nm against a blackbody source. 3 
The iodine cycle results in evaporated tungsten combining with iodine vapor, which then returns to the 
filament in the form of tungsten iodide. The cycle is completed when, on contact with the filament, the 
tungsten iodide dissociates into tungsten and iodine vapor. In this way the filament can operate at 
relatively high temperature and long life without any blackening of the quartz envelope. A typical 
calibration of this lamp is shown in Table 2.2. 

In principle, the spectral radiance of a tungsten lamp can be found by multiplying the spectral 
radiance of a blackbody by the spectral emissivity of tungsten at the same temperature. The measure- 
ments by J. C. de Vos 4 of tungsten emissivity are shown in Figure 2-1. Caution must be used in using the 
measurements with an arbitrary tungsten lamp, since the emissivity of tungsten can be greatly affected 
by parameters such as impurities, crystalline structure, filament geometry, and reflections within the 
lamp envelope. 

In addition to being an excellent secondary standard of radiation, the tungsten filament lamp is a 
good pump for continuous lasers. When used in the quartz-iodine cycle design, it is compact and has a 
relatively high spectral radiance in the 500 nm-2000 nm wavelength range. One-kW lamps have filaments 
about 2.5 cm long and 0.5 cm diameter, and lamp life from 30 to 2000 hr at color temperature between 
3400°K and 3000°K respectively (actual temperature is about 125°K less than the color temperature). 
Its advantages are low cost; simple, inexpensive power supply; and no water cooling. Its prime dis- 
advantage is that its radiance is limited by the melting point of tungsten. 

Mercury Lamps 

The high-pressure mercury capillary lamp is an extremely high radiance source in the 300 nm to 
650 nm wavelength region. An indication of the compactness of the radiation is that 700 W/cm can be 
dissipated in a lamp of 1 mm arc diameter. These lamps operate at pressures up to 200 atm and often 
fail by exploding. Typical lamp life ranges from a few hours to 100 hr at lower power loading. A spectrum 
of a type A PEK lamp 5 operating at 550 V/cm and 1.1 A in a 1 mm-diameter, water-cooled capillary is 
shown in Figure 2-2. These lamps can also operate as pulsed sources at equivalent average power. 6 The 
effect is to increase the continuum relative to the lines. 

Xenon Lamps 

While mercury is an efficient high-intensity source for visible and near-ultraviolet radiation, a need 
exists for a good source in the near infrared, where the major absorption bands of Nd 3+ are present. 
Xenon is an efficient emitter of radiation in the visible and near infrared. The spectral radiance of a 



TABLE 2-1. BLACK-BODY RADIATION FUNCTIONS* 



Ar, 


W(X, T) 


&WdX 


Ar, 


W(X, T) 


Jo WdX 


cm-deg 


W max (T) 


Jo 3 WdX 


cm-deg 


W m »(T) 


^ WdX 


0.050 


2.999 x 10" 7 


1.316 x 10" 9 


0.155 


3.032 x 10" 1 


1.610 x 10~ 2 


0.051 


4.775 x 10" 7 


2.184 x 10~ 9 


0.160 


3.457 x 10- 1 


1.979 x lO" 2 


0.052 


7.452 x 10- 7 


3.552 x 10" 9 


0.165 


3.892 x 10" ' 


2.396 x 10- 2 


0.053 


1.142 x 10" 6 


5.665 x 10- 9 


0.170 


4.332 x 10- 1 


2.862 x 10" 2 


0.054 


1.718 x 10- 6 


8.871 x lO" 9 


0.175 


4.772 x 10- x 


3.379 x 10" 2 


0.055 


2.545 x 10- 6 


1.366 x lO" 8 


0.180 


5.208 x lO" 1 


3.946 x 10- 2 


0.056 


3.709 x 10" 6 


2.068 x 10" 8 


0.185 


5.636 x 10" * 


4.561 x lO" 2 


0.057 


5.326 x 10- 6 


3.084 x 10" 8 


0.190 


6.053 x 10" 1 


5.225 x lO" 2 


0.058 


7.544 x 10" 6 


4.532 x 10- 8 


0.195 


6.455 x 10- x 


5.935 x lO" 2 


0.059 


1.054 x 10- 5 


6.568 x 10- 8 


0.200 


6.840 x lO" 1 


6.690 x lO" 2 


0.060 


1.455 x 10- 5 


9.395 x 10- 8 


0.22 


8.169 x lO" 1 


1.011 x lO" 1 


0.061 


1.985 x 10- 5 


1.327 x 10- 7 


0.24 


9.126 x 10-* 


1.405 x lO" 1 


0.062 


2.676 x 10- 5 


1.853 x 10" 7 


0.26 


9.712 x lO" 1 


1.834 x 10" 1 


0.063 


3.570 x 10" 5 


2.558 x lO" 7 


0.28 


9.972 x lO" 1 


2.282 x 10" x 


0.064 


4.713 x 10" 5 


3.493 x 10- 7 


0.30 


9.971 x 10- 1 


2.736 x 10" l 


0.065 


6.613 x 10- 5 


4.721 x 10" 7 


0.32 


9.771 x lO" 1 


3.185 x 10" 1 


0.066 


7.984 x 10- 5 


6.319 x lO" 7 


0.34 


9.432 x lO" 1 


3.621 x 10" 1 


0.067 


1.025 x 10~ 4 


8.380 x 10" 7 


0.36 


8.999 x 10" 1 


4.040 x 10" * 


0.068 


1.305 x 10" 4 


1.101 x 10~ 6 


0.38 


8.512 x lO" 1 


4.438 x lO" x 


0.069 


1.649 x 10- 4 


1.435 x 10" 6 


0.40 


7.997 x 10- x 


4.813 x 10" 1 


0.070 


2.066 x 10- 4 


1.856 x lO" 6 


0.42 


7.475 x 10" x 


5.164 x 10" 1 


0.071 


2.571 x 10- 4 


2.380 x 10" 6 


0.44 


6.961 x 10" 1 


5.492 x lO" x 


0.072 


3.176 x 10- 4 


3.030 x 10- 6 


0.46 


6.464 x 10- * 


5.796 x 10" x 


0.073 


3.897 x 10- 4 


3.831 x 10- 6 


0.48 


5.990 x 10- 1 


6.079 x 10" x 


0.074 


4.751 x 10- 4 


4.810 x 10~ 6 


0.50 


5.543 x 10- * 


6.341 x 10" x 


0.075 


5.757 x 10" 4 


5.999 x 10- 6 


0.52 


5.125 x 10" 1 


6.583 x 10" 1 


0.076 


6.934 x 10" 4 


7.436 x 10- 6 


0.54 


4.735 x 10" 1 


6.807 x lO" 1 


0.077 


8.304 x 10- 4 


9.162 x 10" 6 


0.56 


4.375 x 10" * 


7.013 x 10" 1 


0.078 


9.891 x 10- 4 


1.122 x 10~ 5 


0.58 


4.042 x lO" x 


7.204 x lO" 1 


0.079 


1.172 x 10~ 3 


1.367 x lO" 5 


0.60 


3.735 x lO" 1 


7.381 x 10" 1 


0.080 


1.382 x 10" 3 


1.657 x lO" 5 


0.62 


3.453 x 10" x 


7.544 x 10" 1 


0.081 


1.621 x 10- 3 


1.997 x 10" 5 


0.64 


3.193 x lO" 1 


7.694 x lO" x 


0.082 


1.893 x 10" 3 


2.395 x 10- 5 


0.66 


2.956 x 10" 1 


7.834 x 10" 1 


0.083 


2.201 x 10" 3 


2.859 x 10" 5 


0.68 


2.737 x lO" 1 


7.963 x lO" x 


0.084 


2.548 x 10- 3 


3.398 x 10" 5 


0.70 


2.537 x lO" 1 


8.083 x lO" 1 


0.085 


2.938 x 10- 3 


4.020 x lO" s 


0.72 


2.354 x 10- 1 


8.194 x lO" 1 


0.086 


3.373 x 10" 3 


4.735 x 10- 5 


0.74 


2.185 x 10" 1 


8.297 x lO" 1 


0.087 


3.859 x 10" 3 


5.555 x lO" 5 


0.76 


2.030 x 10" x 


8.392 x lO" 1 


0.088 


4.397 x 10- 3 


6.491 x 10- 5 


0.78 


1.888 x 10- 1 


8.481 x lO" 1 


0.089 


4.993 x 10" 3 


7.556 x lO" 5 


0.80 


1.758 x 10" 1 


8.564 x lO" 1 


0.090 


5.651 x 10" 3 


8.763 x 10" 5 


0.82 


1.638 x 10" 1 


8.641 x 10- 1 


0.091 


6.373 x 10- 3 


1.013 x lO" 4 


0.84 


1.528 x 10- 1 


8.713 x lO" 1 


0.092 


7.165 x 10" 3 


1.166 x 10~ 4 


0.86 


1.426 x lO" x 


8.780 x 10" 1 


0.093 


8.030 x 10- 3 


1.339 x lO" 4 


0.88 


1.332 x lO' 1 


8.843 x 10" 1 


0.094 


8.973 x 10" 3 


1.532 x 10~ 4 


0.90 


1.246 x 10" * 


8.901 x 10- x 


0.095 


9.998 x 10- 3 


1.747 x 10" 4 


0.92 


1.166 x lO" 1 


8.956 x 10" 1 


0.096 


1.111 x 10~ 2 


1.986 x 10" 4 


0.94 


1.093 x 10" x 


9.007 x 10- x 


0.097 


1.231 x lO" 2 


2.252 x lO" 4 


0.96 


1.024 x 10- 1 


9.055 x 10" 1 


0.098 


1.360 x 10- 2 


2.546 x lO" 4 


0.98 


9.613 x lO" 2 


9.100 x 10" 1 


0.099 


1.500 x lO" 2 


2.870 x lO" 4 


1.0 


9.029 x lO" 2 


9.143 x lO" 1 


0.100 


1.649 x 10- 2 


3.228 x 10" 4 


1.1 


6.679 x 10" 2 


9.319 x 10" 1 


0.105 


2.563 x 10" 2 


5.591 x 10" 4 


1.2 


5.035 x 10" 2 


9.451 x lO" 1 


0.110 


3.785 x 10" 2 


9.162 x 10- 4 


1.3 


3.862 x 10" 2 


9.551 x lO" 1 


0.115 


5.350 x 10" 2 


1.431 x 10" 3 


1.4 


3.007 x 10" 2 


9.629 x lO" * 


0.120 


7.281 x 10" 2 


2.145 x 10" 3 


1.5 


2.375 x 10" 2 


9.690 x lO" 1 


0.125 


9.588 x lO" 2 


3.099 x 10" 3 


1.6 


1.899 x lO" 2 


9.738 x lO" 1 


0.130 


1.227 x 10- 1 


4.336 x lO" 3 


1.7 


1.536 x 10" 2 


9.777 x 10- l 


0.135 


1.530 x 10" 1 


5.897 x 10" 3 


1.8 


1.255 x 10" 2 


9.808 x 10" 1 


0.140 


1.866 x lO" x 


7.822 x 10" 3 


1.9 


1.035 x 10" 2 


9.834 x lO" 1 


0.145 


2.232 x 10" 1 


1.015 x lO" 2 


2.0 


8.612 x 10" 3 


9.856 x 10" 1 


0.150 


2.622 x 10" * 


1.290 x 10" 2 









* From "American Institute of Physics Handbook," D. E. Gray, Ed., McGraw-Hill Book Co. 
Inc., 1963. 



16 Handbook of Lasers 

TABLE 2-2. SPECTRAL IRRADIANCE OF A TYPICAL 

QUARTZ-HALOGEN GE TYPE DXW 1000-WATT 

TUNGSTEN-FILAMENT LAMPf 

FROM 0.25 TO 2.50 ja 

At a Distance of 50 cm with the Lamp Operated at 8.00 Amperes in Watts per (cm 2 nanometer) 

(EG & G Type 595 Tungsten Halogen Lamp Standard) 

DERIVED PHOTOMETRIC CALIBRATIONS 

Illuminance at 50 cm: 8.5987 — 01 Lumen/sq cm 

7.9885 + 02 Lumen/sq ft or foot candles 
Luminous Intensity: 2.1497 + 03 Lumen/Steradian or Candela 
CIE Chromaticity Coordinates: X = 0.4321 Y = 0.4019 
Correlated Color Temperature: 3063 Deg Kelvin 

This standard has been prepared by transfer measurement from a group of lamps calibrated by the National Bureau of 
Standards. Points of comparison are marked with an asterisk (*) in the table. The interpolated points lie on the black- 
body curve passing through the two nearest comparison points. The data have been verified in accordance with current 
radiometric calibration lab quality assurance procedures. 



Wavelength, 


Spec Irradiance, 


Wavelength, 


Spec Irradiance, 


Wavelength, 


Spec Irradiance, 


Nanometers 


Watts\(sq cm-nm) 


Nanometers 


Watts/(sq cm-nm) 


Nanometers 


Watts/(sq cm-nm) 


250* 


1.873-08* 


320* 


3.701-07* 


550* 


1.109-05* 


252 


2.110-08 


325 


4.302-07 


560 


1.180-05 


254 


2.371-08 


330 


4.972-07 


570 


1.251-05 


255 


2.511-08 


335 


5.715-07 


575 


1.286-05 


256 


2.658-08 


340 


6.535-07 


580 


1.321-05 


258 


2.974-08 


345 


7.436-07 


590 


1.391-05 


260* 


3.322-08* 


350* 


8.421-07* 


600* 


1.468-05* 


262 


3.701-08 


355 


9.449-07 


610 


1.532-05 


264 


4.116-08 


360 


1.056-06 


620 


1.604-05 


265 


4.338-08 


365 


1.175-06 


625 


1.639-05 


266 


4.569-08 






630 


1.674-05 


268 


5.062-08 


370* 
375 


1.302-06* 
1.443-06 


640 


1.742-05 


270* 


5.599-08* 


380 


1.594-06 


650* 


1.809-05* 


272 


6.156-08 


385 


1.754-06 


660 


1.873-05 


274 


6.758-08 


390 


1.924-06 


670 


1.934-05 


275 


7.077-08 


395 


2.103-06 


675 


1.964-05 


276 


7.407-08 






680 


1.994-05 


278 


8.105-08 


400* 
410 


2.292-06* 
2.683-06 


690 


2.051-05 


280* 


8.855-08* 


420 


3.108-06 


700* 
710 


2.107-05* 


282 


9.650-08 


425 


3.333-06 


2.153-05 


284 


1.050-07 


430 


3.565-06 


720 


2.196-05 


285 


1.095-07 


440 


4.054-06 


725 


2.217-05 


286 


1.141-07 






730 


2.237-05 


288 


1.238-07 


450* 


4.572-06* 


740 


2.276-05 






460 


5.140-06 


750* 


2.312-05* 


290* 


1.342-07* 


470 


5.737-06 


760 


2.344-05 


292 


1.447-07 


475 


6.045-06 


770 


2.373-05 


294 


1.558-07 


480 


6.360-06 


775 


2.387-05 


295 


1.617-07 


490 


7.006-06 


780 


2.400-05 


296 


1.677-07 






790 


2.425-05 


298 


1.801-07 


500* 


7.671-06* 










510 


8.337-06 


800* 


2.447-05* 


300* 


1.933-07* 


520 


9.015-06 


810 


2.465-05 


305 


2.297-07 


525 


9.357-06 


820 


2.481-05 


310 


2.710-07 


530 


9.701-06 


830 


2.495-05 


315 


3.177-07 


540 


1.039-05 


840 


2.507-05 



t Data courtesy of E G & G, Inc., Electro-Optics Division, 35 Congress St., Salem, Mass. 01970. 



2 Incoherent Optical Sources 17 

TABLE 2-2. SPECTRAL IRRADIANCE OF A TYPICAL 

QUARTZ-HALOGEN GE TYPE DXW 1000-WATT 

TUNGSTEN-FILAMENT LAMP— (Continued) 



Wavelength, 


Spec Irradiance, 


Wavelength, 


Spec Irradiance, 


Wavelength. 


Spec Irradiance, 


Nanometers 


Watts/(sq cm-nm) 


Nanometers 


WattsKsq cm-nm) 


Nanometers 


Watts /(sq cm-nm) 


850 


2.517-05 


1150 


2.226-05 


1800* 


1.036-05* 


860 


2.525-05 


1160 


2.209-05 


1825 


9.995-06 


870 


2.531-05 


1170 


2.187-05 


1850 


9.646-06 


880 


2.535-05 


1180 


2.165-05 


1875 


9.311-06 


890 


2.538-05 


1190 


2.157-05 


1900* 


8.988-06* 


900* 


2.539-05* 


1200* 


2.145-05* 


1925 


8.679-06 


910 


2.539-05 


1225 


2.095-05 


1950 


8.381-06 


920 


2.537-05 


1250 


2.045-05 


1975 


8.095-06 


930 


2.533-05 


1275 


1.995-05 






940 


2.528-05 






2000* 


7.820-06* 






1300* 


1.944-05* 


2025 


7.560-06 


950 


2.522-05 


1325 


1.893-05 


2050 


7.309-06 


960 


2.515-05 


1350 


1.841-05 


2075 


7.068-06 


970 


2.507-05 


1375 


1.791-05 






980 


2.498-05 






2100* 


6.836-06* 


990 


2.487-05 


1400* 


1.741-05* 


2125 


6.625-06 






1425 


1.690-05 


2150 


6.422-06 


1000* 


2.476-05* 


1450 


1.639-05 


2175 


6.225-06 


1010 


2.460-05 


1475 


1.590-05 






1020 


2.449-05 






2200* 


6.035-06* 


1030 


2.435-05 


1500* 


1.542-05* 


2225 


5.873-06 


1040 


2.419-05 


1525 


1.494-05 


2250 


5.715-06 






1550 


1.448-05 


2275 


5.561-06 


1050 


2.409-05 


1575 


1.402-05 






1060 


2.390-05 






2300* 


5.413-06* 


1070 


2.375-05 


1600* 


1.358-05* 


2325 


5.281-06 


1080 


2.358-05 


1625 


1.315-05 


2350 


5.153-06 


1090 


2.337-05 


1650 
1675 


1.274-05 
1.233-05 


2375 


5.028-06 


1100* 


2.325-05* 






2400* 


4.906-06* 


1110 


2.309-05 


1700* 


1.194-05* 


2425 


4.802-06 


1120 


2.287-05 


1725 


1.152-05 


2450 


4.701-06 


1130 


2.265-05 


1750 


1.112-05 


2475 


4.601-06 


1140 


2.249-05 


1775 


1.073-05 


2500* 


4.503-06* 



Estimated accuracy of illuminance and luminous intensity data is ± 3 %. 
Estimated accuracy of chromaticity coordinates is ±0.2%. 
Estimated accuracy of correlated color temperature is ± 5°K. 

Spectral irradiance uncertainties (NBS Standards): ±3% visible widening to ± 5% at 2.5 microns and to ± 8% at 0.25 
microns. Refer to NBS Technical Note 262. 

35-A, 78-V, DC xenon lamp is shown in Figure 2-3. 7 The arc length is 5 cm, bore diameter is 5.5 mm and 
the fill pressure is 2 atm. Under these conditions the radiance of the lines (about 5A wide) is over an 
order of magnitude more intense than the continuum. Therefore the spectra were taken at two different 
scale factors. Since the lines are narrow, the energy in the continuum is comparable to the lines. It is 
claimed that a 6.2 mm-diameter, 5 cm-long arc can continuously dissipate 10 kW (100 V and 100 A) 
power. 8 At 6 kW, over 100-hr life has been obtained with no appreciable deterioration of the light out- 
put. 

Krypton Lamps 

The spectral characteristics of krypton are quite similar to xenon. Krypton, being a lighter gas, has 
a greater thermal conductivity and is therefore a less efficient radiator than xenon. However, the lines of 
krypton radiate at wavelengths more favorable than xenon for pumping Nd lasers, so that it is a more 
efficient cw pump. 9 The radiance of a krypton lamp operating under conditions similar to those of the 
xenon lamp described above is shown in Figure 2-4. 7 Arc length = 5 cm, bore diameter = 5.5 mm, fill 
gas is 2 atm Kr, current = 35 A and voltage = 65 V. 



18 



Handbook of Lasers 



0.50 
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Fig. 2-2. Spectrum of PEK type A mercury capillary lamp. 



2 Incoherent Optical Sources 19 




20 Handbook of Lasers 




2 Incoherent Optical Sources 21 



Alkali Vapor Lamps 

Alkali metals attack quartz and can only be operated in quartz envelopes when combined with a 
halide. In the halide form (usually iodide and as an additive to Hg) and at the softening temperature of 
quartz, the vapor pressure of the alkali halide is still relatively low and contributes only part of the 
radiation from the arc. Furthermore, at high wall temperatures the alkali halides react with quartz, so 
that for reasonable life the lamp must operate at modest wall loadings. For these reasons they do not 
appear to be attractive for laser pumps. 

Recent advances in lamp construction materials and techniques have allowed the alkali metal to 
become an important class of laser pump discharges. The alkali metals do not attack alumina. Lamp 
manufacturers have developed translucent polycrystalline alumina (PCA) tubes and methods for sealing 
refractory metal end caps. Pure alkali metal discharges can operate in these lamps at pressures in excess 

SODIUM EMISSION SPECTRUM 



. JA 



I 
2£ 



k—L 



torr 



30 



t — *—* 



_ILd 



j,JiiLil 



*> ft n"^n 



240 




WAVELENGTH (MICRONS) 

Fig. 2-5. Spectral radiation from a sodium lamp. 



22 



Handbook of Lasers 



of one atmosphere and at wall temperatures over 1900°K. More recently, techniques for rapid growth of 
single crystal alumina (sapphire) tubes at relatively low cost have been developed. Thus, transparent 
rather than translucent envelopes can be used. This permits improved spectroscopic measurements and, 
more important, it increases the radiance of the lamp. 

The spectra from alkali metal lamps are dominated by radiation from the lowest excited states 
(P states) of the neutral atom to the ground state. Since these transitions occur in the visible and near 
infrared, the arc core is radiation cooled and typically operates no higher than 4500°K. Thus the radiative 
efficiency of the alkali metals is very high. Since the radiation is to the ground state (resonance lines), 
they are absorbers as well as emitters of their own radiation. Consequently the well known phenomenon 
of line reversal occurs, when the radiation from the hot core atoms is absorbed by the cooler atoms near 
the wall. The degree of self absorption is a strong function of alkali metal vapor pressure and can 
radically alter the lamp spectrum. Figures 2-5 to 2-8 are spectra of alkali metals at various pressures. 10 
They were taken at 6 amp in 7 mm-ID PCA envelopes. The spectra are wavelength calibrated, and all 

POTASSIUM EMISSION SPECTRUM 



torr 




T 
.4 



T 
.6 



i — i — i — ' — i — " — r 

.8 1.0 1.2 1.4 

WAVELENGTH (MICRONS) 

Fig. 2-6. Spectral radiation from a potassium lamp. 



r 

1.6 



2 Incoherent Optical Sources 23 



RUBIDIUM EMISSION SPECTRUM 




WAVELENGTH (MICRONS) 

Fig. 2-7. Spectral radiation from a rubidium lamp. 



but the sodium spectra were taken at the same conditions. The scale factor on the sodium spectra is 
compressed about 50 % relative to the other spectra. At high pressures the extreme broadening of the 
lines is believed to be due to molecular radiation. These lamps were operated at power levels as high as 
450 W/cm 3 and 63 W/cm 2 of inner-wall surface area. 

The potassium lamp has been shown to be an excellent pump for Nd:YAG cw lasers. 11 In the study 
undertaken, the potassium was added to mercury primarily to improve the V-I characteristic, but this 
modification is not essential. The spectrum used for pumping Nd:YAG and the absorption spectrum of 
Nd : YAG are shown in Figure 2-9. The lamp had a 7.5 mm-ID sapphire wall, electrode spacing of 3.5 
cm, K to Hg amalgam weight ratio of 1 to 4. The electrical characteristics are 100 V and 5 A. The full 
scale spectral radiance is 8.26 watt (ster-cm 2 -nm) _1 . The estimated potassium pressure is 200 Torr. 
The full potential of these lamps for laser pumps has not been realized, since the lamp must operate 
in a bulky evacuated outer jacket to prevent oxidation of the Ta and Nb end caps. However, work is 
underway in many laboratories to allow air operation of these lamps. This will not only allow for better 
geometrical coupling of the lamp to the rod, but should also increase the power dissipated, since 
convection and forced-air cooling can occur. 



24 Handbook of Lasers 



CESIUM EMISSION SPECTRUM 




i " i i i ■ r 

.8 1.0 1.2 1.4 

WAVELENGTH (MICRONS) 

Fig. 2-8. Spectral radiation from a cesium lamp. 



Non-Wall Stabilized Arc Lamps 

One of the limitations of average power in a wall-stabilized gas discharge is the melting point and 
thermal and mechanical stresses in the wall envelope. These problems can be eliminated, if the envelope 
can be removed from the hot gas area. When this is done, other means for locating the arc must be 
maintained. 

SHORT ARC. If the electrodes are placed sufficiently close together, the electric field lines will 
stabilize the arc. Short arcs have radiances well in excess of wall-stabilized arcs, since kilowatts of power 
are dissipated in radiating volumes of about 10 mm 3 . 12 Figures 2-10a, 2-10b and 2-10c show spectral 
irradiance curves for a 1 50- watt short-arc xenon lamp, a 200- watt short-arc mercury lamp, and a 200-watt 



2 Incoherent Optical Sources 25 



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Fig. 2-9. Above: Optical density of 6 mm thick YAG:0.7% Nd. Below: Spectral radiance of K-Hg lamp. 



short-arc xenon-mercury lamp. Figures 2-1 la, 2-1 lb, and 2-1 lc give spectral irradiance as a function 
of wavelength for 1000-watt short-arc versions of the same three types of lamps, xenon, mercury and 
xenon-mercury. The geometry of the short arc makes it unsuitable for pumping conventional, cylindrical 
laser rods. 

VORTEX-STABILIZED ARC. The vortex-stabilized arc is stabilized primarily by flowing gas in 
the form of a vortex around the arc core, which creates forces keeping the arc in a cylindrical volume. 
For a 25-kW source the arc dimensions are typically 3 mm diameter by 10 mm long. 13 Prototypes have 
been operated at input levels as high as 150 kW. The spectrum of an argon vortex-stabilized arc is shown 
in Figure 2-12. These sources have not been used for laser pumping, since they are extremely rich in 
ultraviolet radiation. Therefore, they are relatively inefficient radiators at the pump bands of present 
solid state laser materials, and the ultraviolet causes damage to the laser rods. Also, the requirement of 
flowing gas is undesirable. The plasma jet is similar to the vortex arc. By changing the electrode and 
vortex geometry, arc lengths of 5 cm with diameters of 1.2 mm have been obtained. 14 



26 



Handbook of Lasers 



TYPICAL OUTPUT SPECTRA 




2000 2400 3000 



4000 5000 6000 

WAVELENGTH (Angstroms) 



7000 



8000 



9000 



§ 7 

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6 .015 

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200 WATT XENON-MERCURY LAMP 


- 














• 


:AT. NO.: C-47-35-2 (HANOVIA 901-B1) OPERATED 
AT 20 VOLTS, 9.5 AMPS. 












































































































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MANUFACTURER'S DATA 


— 


/ 


















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Operating Current 9.5-8 amps 


















Horizontal Intensity 880 candles 


















Flux 5000 lumens 
Avg. Brightness 190 cd/mm 2 


















Eff. Arc. Size (W.x Ht.) 0.75 x 1.5 mm _ 


















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2000 



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4000 5000 6000 7000 8000 

WAVELENGTH (Angstroms) 

Fig. 2- 10a. Spectral irradiance of a 150- watt short-arc xenon lamp from 2000 to 9000 A. 

Fig. 2-10b. Spectral irradiance of a 200-watt short-arc mercury lamp from 2000 to 9000 A. 

Fig. 2-10c. Spectral irradiance of a 200-watt short-arc xenon-mercury lamp from 2000 to 9000 A. 



9000 



2 Incoherent Optical Sources 27 



TYPICAL OUTPUT SPECTRA 



50 
40 



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1 




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♦MULTIPLY READINGS 
BELOW 3000 BY 0.1 
*X0.1 



1000 WATT XENON LAMP 

CAT. NO.: C-45-35-51 (HANOVIA 976-C1) OPERATED 
AT 23 VOLTS, 43 AMPS. 

MANUFACTURER'S DATA 




2000 



20-26 volts 
43.5 amps 
4500 candles 
32000 lumens 
350 cd/mm 2 
1.5x3. 0mm 
1000 hours 



1000 WATT Xe LAMP CAT. NO.: C-45-35-51 
1000 WATT OZONE FREE Xe LAMP CAT. NO.: C-45-35-53 5 



Operating Voltage 

Operating Current 

Horizontal Intensity 

Flux 

Avg. Brightness 

Eff. Arc. Size (W.x Ht.) 

Avg. Life 




3000 



4000 5000 6000 

WAVELENGTH (Angstroms) 



7000 



8000 



9000 




2000 2300 3000 



4000 



5000 6000 

WAVELENGTH (Angstroms) 



7000 



8000 



9000 



100 

80 

! 60 

; so 

40 
30 



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g 3 15 

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CC O 5 

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o 0.3 
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0.1 

0, 



0.08 











- 






































1000 WATT XENON-MERCURY LAMP 

:AT. NO.: C-47-35-51 (HANOVIA 977-BI) OPERATED 
AT 27 VOLTS, 35 AMPS. 






















































bi - 
























NOTE: Data for 1000 watt Ozone-free Xenon- 






















Mercury Lamp (Cat No: C-47-35-53) is not 








1 














due to the ozone-free envelope can be cal- 








II 














c 


:ulated from the xenon Lamp curves above. 














































































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MANUFACTURER'S DATA 
Operating Voltage 30-38 volts 
Operating Current 33-26 amps 








i 


\/ 








1 






I 


























*X0.1 


♦MULTIPLY READINGS BELOW 2300 BY 0.1 


r Horizontal Intensity 5000 candles 
r Flux 45000 lumens 




















Avg. Brightness 320 cd/mm? 
EH. Arc. Size (W.x Ht.) 1 .5 x 3.0 mm 
Avg. Life 1000 hours 






















- 






































. 








' 





2000 2300 3000 



4000 5000 6000 

WAVELENGTH (Angstroms) 



7000 



8000 



9000 



Fig. 2-1 la. Spectral irradiance of a 1000-watt short-arc xenon lamp from 2000 to 9000 A. 

Fig. 2-1 lb. Spectral irradiance of a 1000-watt short-arc mercury lamp from 2000 to 9000 A. 

Fig. 2-1 lc. Spectral irradiance of a 1000-watt short-arc xenon-mercury lamp from 2000 to 9000 A. 



28 



Handbook of Lasers 




.6 .7 .8 .9 1.0 I.I 1.2 1.3 1.4 
WAVELENGTH [fi) 

Fig. 2-12. Radiance of a 17 kW vortex-stabilized argon arc lamp. 
200 amp, 85 volts, 14.2 atm. Arc 10 mm x 1.8 mm. Spectral resolu- 
tion = 50 nm. 



The Sun 

The use of the sun eliminates the need for electrical power for energizing the laser rod. For space 
applications, where power supply size, weight, and life are at a premium, direct laser pumping with the 
sun may be useful. A Nd : YAG rod has been successfully solar pumped. 15 Output power of 90 mW has 
been obtained and the authors calculate that 10 W can be reached. The spectral irradiance of the sun 
93 x 10 6 mi from the sun is shown in Figure 2-14. The spectral irradiance as attenuated by the earth's 
atmosphere is shown in Figure 2-13 15 . 




.6 .7 .8 .9 1.0 I.I 
WAVELENGTH (/*) 

Fig. 2-13. Solar spectral irradiance, as modified by the earth's atmosphere. 



2 Incoherent Optical Sources 29 




(rf-tt>- { u»/SOH) 3DNVIOV1HII 1VH1D3.IS 



30 



Handbook of Lasers 



PULSED SOURCES 



Xenon Flashlamps 

The operating conditions for xenon flashlamps can vary over extreme ranges of current densities. 
At low current densities the emittance is dominated by bound-bound electron transitions (line emission). 
As the current density (and pressure) is increased, the lines broaden and saturate at the blackbody 
radiance for the core temperature. (Under the usual operating condition for flashlamps, local thermody- 
namic equilibrium exists, so that all particles in a given neighborhood are considered to be at the same 
temperature.) As the current density is further increased, the additional power is primarily dissipated by 
radiation from free-bound and free-free electron transitions (continuum radiation). At first these 
transitions are of low energy — i.e., infrared radiation. As the current density is increased, the infrared 
continuum saturates at the blackbody radiance, so that the additional continuum radiation shifts to 
the ultraviolet. An example of these phenomena is shown in Figures 2-15 and 2-16. 16 In Figure 2-15 the 
line radiation and the infrared continuum radiation with less than 1 eV energy has saturated at the core 
temperature of 1 1,500°K. In Figure 2-16 the input energy is approximately doubled. Here the continuum 
near the lines is as intense as the lines, and the infrared is optically thick up to about 1.6 eV. Note that 
the ultraviolet energy is increasing much faster than the infrared energy. Also note that the temperature 
increases slower than P 1/4 , which would be the case for a blackbody distribution. 

At low current densities the spectral characteristics of xenon flashlamps can be realized. In Figure 
2-17 the spectrum is shown of a 5 cm-long, 1.5 mm-diameter bore, 900-torr xenon flashlamp. 17 The 
lamp operated at 0.75 j/pulse, 175 pps, 50 A current in a 20 jusec pulse duration. 

Krypton Flashlamps 

The characteristics of krypton flashlamps are qualitatively similar to xenon flashlamps. That is, at 
high current densities the spectrum is dominated by continuum radiation, which is optically thick 

PHOTON ENERGY IN ELECTRON, A 
2066 3099 6199 12,400 




6 5 4 3 2 10 

PHOTON ENERGY, ELECTRON VOLTS 

Fig. 2-15. Spectral radiance of a 1.27 cm thick, 30 
cm long xenon plasma filled to 150 Torr. Input energy of 
3140 J; 2580 A/cm 2 peak current density. Data points 
above dotted lines indicate radiance of spectral lines. 




6 5 4 3 2 I 

PHOTON ENERGY, ELECTRON VOLTS 

Fig. 2-16. Same lamp as in Figure 2-15, but 
with input energy increased to 6400 J; 4480 A/cm 2 
peak current density. (Figures 2-15 and 2-16 re- 
printed from [1 6] by permission of Pergamon Press). 



2 Incoherent Optical Sources 31 

(opaque, blackbody) in the infrared and thin in the ultraviolet. As the current density increases, the 
boundary between saturated blackbody radiation and unsaturated, optically thin radiation shifts to- 
wards the ultraviolet. It has been found that the efficiency of continuum radiation from krypton is poorer 
than from xenon. 18 This is attributed to the fact that the krypton atom is lighter than the xenon atom, so 
that the thermal conduction energy loss to the wall is greater, resulting in a smaller percentage of energy 
dissipated through radiation. Therefore, there is no advantage to using krypton instead of xenon when 
continuum radiation dominates. At lower current densities appreciable line radiation is observed. These 
lines are shifted towards the visible, relative to xenon, and better match the absorption spectrum of 
Nd : YAG, which makes it a superior laser pump. The spectrum of a low-energy, pulsed krypton lamp 
operating at conditions similar to the xenon lamp of Figure 2-17 is shown in Figure 2-18. The current 
required to obtain 0.75 j at 900 Torr is 63 A compared with 50 A for xenon. 17 

Pulsed Alkali Vapor Lamps 

As in the case of krypton flashlamps, when sufficient ionization occurs so that continuum radiation 
dominates, the spectral enhancement desired from line emitters is lost. However, if the peak power is 
kept relatively low, the resonance line radiation from the alkali metals can strongly dominate the spectral 
emission. Mixtures of alkali metals can be placed in the same lamp. The spectrum will be dominated by 
the heavier atom, which emits further in the infrared, but significant radiation from the other species 
will be obtained. Considering the strong spectral dependence on fill composition, pressure, current 
density and lamp diameter, a large variety of spectral profiles can be obtained. Examples of a few 
combinations are shown in Figures 2-19 and 2-20. 19 These lamps were made with either poly crystalline 
alumina or sapphire envelopes with fin. OD and ^in. ID. The arc length was 2-3 in. and average power 
dissipated was 140-230 watts. Peak power in Figures 2- 19a and 2- 19b was 10.2 and 7.1 kW respectively. 
The radiation modulation at these average powers was in excess of 95 %, but with increasing average 
power, the percent modulation will decrease, because of continuous radiation being emitted by the hot 
alumina envelope. 

Theta Pinch Discharge Lamps 

In the theta pinch discharge the lamp consists of a closed, cylindrical quartz tube filled with gas 
typically at pressures of 1-10 Torr. Energy is inductively coupled to the gas through a coil of one or 
more turns, which passes very high currents when a capacitor is discharged through a switch such as a 
spark gap. The magnetic field created not only ionizes the gas, but increases its density by driving the 
ionized particles toward the center of the tube. This results in an output of extremely high radiance, 
which typically lasts for about 10 fisec. The efficiency of this process is relatively low. The dynamics of 
the discharge are complicated and difficult to analyze. Typical spectra from a number of gases under 
similar experimental conditions are shown in Figure 2-21. 20 

Shock Wave Generated Discharge Lamps 

This configuration is similar to the theta pinch, except that the tube has a coaxial inner tube. This 
prevents the pinch from occurring, resulting in strong, cylindrically imploding shock waves. An advan- 
tage of this arrangement is that a laser rod can be placed inside the lamp along the axis. This arrangement 
has successfully pumped a Nd : CaW0 4 laser rod. Argon fill of 10 Torr gave the best performance. The 
spectrum obtained by discharging a 1 /if capacitor is shown in Figure 2-22. 21 

Z-Pinch Discharge Lamps 

This discharge is a linear version of the theta pinch, so that electrodes are required. It differs from a 
conventional flashlamp in that the combination of low fill pressure ( ~10 Torr) and high peak power 
(10 7 W) result in large shock waves. Because electrodes are used, the energy coupled into the gas from 
the capacitor is large compared with the theta pinch. Thus the discharge is, more efficient. This tube in a 
coaxial version was successful in pumping a Nd laser. A lamp spectrum at 50 j input along with blackbody 
curves are shown in Figure 2-23. 22 



32 Handbo.ok of Lasers 




2 Incoherent Optical Sources 33 




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34 



Handbook of Lasers 



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2 Incoherent Optical Sources 35 



o< - 




Fig. 2-21. Output energy spectral density 
at 450 J input in seven gases: Each point re- 
presents the average energy in a 50-A band. 
Each curve is displaced vertically one order of 
magnitude from the one below it. The line 
surrounding the gas label marks the value 0.2 
J per 100 A for that gas. Thus xenon is almost 
entirely above 0.2 and oxygen mostly less than 
0.2J/100 A. The calibration extends from 0.25 
to 0.7 p. The scale below 0.25 /x is uncalibrated. 
All the lamps were 30 mm in diameter and filled 
to a pressure of 100 Torr. Abscissa is energy in 
joules per 100 A. Ordinate is the wavelength in 
microns. 



0.2 0.3 0.4 0.5 0.6 0.7 
WAVELENGTH [fl) 



36 



Handbook of Lasers 



3 



E 



CM 

E 
o 



10 = 



>- 



Q 
UJ 

I— 
< 



10" = 



10 = 



10 = 




Fig. 2-22. Peak radiated intensity for 25- and 15-kV discharges. Dashed 
curves refer to 10-Torr argon and solid curves to 0.5-Torr argon fill pressures. Tube 
size: 25 x 25 mm with 10-mm i.d. 



Ablating Wall Flashlamps 

At high current densities wall material evaporates and can contribute to the radiative output. Wall 
material, such as plastics and glass, can be used. With plastic envelopes the lamp becomes rugged and 
can have long life. In addition, if the lamp operates with air at 1 atm, no pumping is required. The lamps 
are moderately efficient, radiating about 25 % of the input energy over a wide band extending from the 
ultraviolet to the infrared range of transmission of the plastic. An example of the spectrum of such a 
lamp with a plexiglass rod along the axis to increase the wall area is shown in Figure 2-24. 23 Additional 
results without a central tube, using a lucite envelope, are shown in Figure 2-25. 24 



2 Incoherent Optical Sources 37 




2000 



4000 



6000 



8000 



X(A°) 



Fig. 2-23. Spectral irradiance of argon filled at 20 Torr. x and + refer to two dif- 
ferent photomultipliers. Blackbody radiance curves normalized to 5000 A are also shown. 



100 
80 

*Z 60 



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CM 



CO 



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3.5 4.0 



4.5 



5.0 



5.5 60 



6.5 



70 



WAVELENGTH (A xlO 3 ) 



Fig. 2-24. Spectral radiance of a plexiglas ablating wall lamp. Measurements were taken through a quartz window. 
Fill pressure was 0.1 Torr. 



38 



Handbook of Lasers 



10 



<n 



o 

< 
or 



v> 
I 

o 

< 
I 

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2.630kj 1.98cm bore 13.3 cm length 
0.945 Kj 1.27cm bore 13.3cm length 



0.236 kj 1.27cm bore 13.3cm length! 
0.945 kj 1.98 cm bore 13.3cm length. 



ABLATIVE LAMP 

XENON LAMP 

BLACK BODY COMPARISON 



JL 



3500 4000 4500 5000 5500 6000 
WAVELENGTH (A ) 

Fig. 2-25. Spectral radiance of lucite ablating wall lamps. Fill pressure was a few Torr. 



1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 
10. 
11. 
12. 
13. 
14. 

15. 
16. 

17. 

18. 
19. 

20. 
21. 

22. 
23. 

24. 



REFERENCES 

M. Pivovonsky and M. R. Nagel, "Tables of Blackbody Radiation Functions," The Macmillan Co., New York, (1961). 
R. Stair, R. G. Johnston and E. W. Halbach, /. Res. Nat. Bur. Stand. 64A, 291 (1960). 

R. Stair, W. E. Schneider and J. K. Jackson, "A New Standard of Spectral Irradiance," NBS Report 8014, June, 1963. 
J. C. deVos, Physica, 20, 690 (1954). 

D. Ross, "Lasers Light Amplifiers and Oscillators," Academic Press, London and New York, 1969. 

W. Elenbass, "High Pressure Mercury Vapor Lamps and their Applications," Philips Technical Library, Eindhoven, (1965). 

I. Liberman and R. L. Grassel, Appl. Optics, 8, 1875 (1969). 

J. W. Stearn and D. J. Colliver, /. Sci. Instrum., 43, 52 (1966). 

T. B. Read, Appl. Phys. Lett., 9, 342 (1966). 

K. Schmidt, Proc. 6th Int. Conf. on Ionization Phenomena in Gases, Vol. 3, pp. 323-330, Paris, 1963. 

I. Liberman, D. A. Larson and C. H. Church, IEEE J. Quant. Electronics, QE-5, 238 (1969). 

Oriel Optics Corp., Specification Sheet. 

Giannini Scientific Corp., Bulletin 15-007A. 

E. F. Stresino and R. C. Eschenbach, " Operating Parameters of a Linde Arc Radiation Source for Terrain Illumination," 
Tech. Rept. AFAL-TR-66-204, Wright-Patterson Air Force Base, Ohio, (June, 1966). AD-485125. 

J. Bordogna, et al., "Solar Pumped Laser" Contract NAS 9-3671 NASA, Houston, Texas (Nov. 1965). N66-19516. 

C. H. Church, R. G. Schlecht and I. Liberman, /. Quant. Spectrosc. Radiat. Transfer, 8, 403 (1968). 

N. L. Yeamans and J. E. Creedon, " Long-Life High-Repetition-Rate Flash Tubes," Tech. Rept. ECOM-3043, US Army 

Electronics Command, Ft. Monmouth, N.J., November 1968. 

I. S. Marshak, Appl. Optics, 2, 793 (1963). 

J. E. Creedon, W. Bayha and S. Schneider, " Pulsed Alkali Vapor Lamps," Tech. Rept. ECOM-3051, US Army Electronics 

Command, Ft. Monmouth, N.J., December 1968. 

J. M. Feldman, J. Appl. Phys., 37, 674 (1966). 

R. G. Buser, A. Papayoanou, and D. Ramm, /. Appl. Phys., 38, 28 (1967). 

R. G. Buser and D. Ramm, Appl. Optics, 5, 627 (1966). 

R. Goldstein, F. N. Mastrup and W. L. Shackleford, "Ablating Wall Annular Flashlamp," Tech. Rept. AFAL-TR-66-15, 

Wright Patterson AF Base, Ohio, March 1966. 

R. G. Buser and W. P. Rahilly, Appl. Optics, 7, 523 (1968). 



Atmospheric Transmission 

William Eppers 

Air Force Avionics Laboratory 

Wright-Patterson Air Force Base 

Dayton, Ohio 45433 



Optical transmission of energy is most usually expressed by : 

T=extf- aR \ 

where a is the attenuation coefficient or extinction coefficient and R is the length of the transmission path. 
The attenuation coefficient is the result of two processes — scattering and absorption. The scattering 
portion of the attenuation coefficient may be further broken down into scattering from air molecules and 
from aerosols. Scattering from air molecules is called Rayleigh scattering and varies as the altitude. 
Scattering from aerosols is a function among other things, of atmospheric pressure and geographic 
location — distinction often being made on the basis of maritime and continental aerosols. The data 
presented in this chapter do not reflect this distinction and therefore must be considered as qualitative. 
The majority of the existing experimental and theoretical work in atmospheric transmission has been 
involved with incoherent, broad-band sources and must be evaluated with care, since the absorp- 
tion bands consist of a multiplicity of lines, whose width and strength depend upon the pressure and 
concentration of the particular absorbing constituent. 14 Figures 3-1 through 3-4 display the broad- 
band transmission for various atmospheric conditons. 

Figures 3-5 through 3-11 provide a convenient method of evaluating the slant path transmittance at 
a variety of wavelengths for a model standard clear atmosphere. Figures 3-12 through 3-14 give the 
amount of precipitable water under various conditions and Figures 3-15 through 3-21 give the broad 
band transmission from 0.3 to 15 n due to various amounts of water vapor. 

Calculation of transmission of laser radiation requires more exact knowledge of atmospheric 
absorption. Figure 3-22 gives absorption curves for various atmospheric gases. The absorption due to 
these gases plus water vapor and the scattering due to dust, clouds, and other pollutants all contribute 
to degradation of the optical transmission. 

Figures 3-23 through 3-32 give experimental transmission data over a 300-meter path at sea level 
near the Chesapeake Bay. Higher resolution data are generally obtained by observing the sun through 
the entire atmosphere and sorting out the Fraunhofer lines from the absorption due to the earth's 
atmosphere (telluric lines). Figures 3-33 through 3-94 show the solar spectrum from 2.8 to 23.7 \i, as 
monitored at 10,000 feet in the Swiss Alps. Even at this height, the 2.6 n band is completely opaque. 

Figures 3-95 through 3-115 show the solar spectrum from 0.82 to 3.41 n, as measured at 40,000 
feet, where the atmosphere is sufficiently thin to transmit even in the regions of strong absorption. 
The symbols in the spectra are as follows. A numbered dot below the spectral trace is only for later 
reference. A dot above the trace indicates water vapor absorption, and vertical lines indicate 2 and 
C0 2 absorptions. Open triangles indicate CH 4 . Crossed open circles are N 2 and asterisks are CO. 
Solar identifications have been added where they are known. The resolution over the entire range is 
about 10,000. 

Figure 3-116 shows absorption through one atmosphere near 0.69 microns, while Figure 3-117 
shows the emission wavelength of a ruby laser as a function of laser rod temperature. Figures 3-118 
and 3-119 give experimental attenuation coefficients for the 1.15 fi He-Ne laser, while Figure 3-120 in- 
dicates the lack of atmospheric absorption near the 1.064 n Nd 3+ laser output. Figures 3-121 through 
3-125 give the calculated water vapor and carbon dioxide absorption for the 10.59 fi laser under varying 
conditions. 

39 



40 



Handbook of Lasers 



Underwater transmission is spectrally limited to the near visible, as shown in Figures 3-126 and 3-127. 
Figure 3-128 shows some typical longtime variations in the transmission at a given wavelength, while 
Figure 3-129 plots the collimated versus the diffuse attenuation lengths for long underwater path lengths. 



TABLE 3-1. LASER LINES 

STRONGLY ABSORBED BY THE 

ATMOSPHERE 



Laser 


A, microns 


Absorber 


Atomic krypton 


1.7843 


H 2 


Atomic krypton 


1.9211 


H 2 


Tm +3 -CaW0 4 


1.911 


H 2 


Tm +3 -CaW0 4 


1.916 


H 2 


U +3 -SrF 2 


2.472 


H 2 


U +3 -CaF 2 


2.511 


H z O 


Atomic krypton 


2.5234 


H 2 


U +3 -BaF 2 


2.556 


H 2 


U +3 -CaF 2 


2.613 


H 2 


Atomic neon 


3.391317 


CH 4 


Carbon monoxide 


5.2 to 7 


H 2 


Cesium 


7.1821 


H 2 


Atomic neon 


18.3040 


H 2 


Atomic neon 


20.351 


H 2 



TABLE 3-2. LASER LINES WITH WEAK TO MODERATE 
ABSORPTION BY THE ATMOSPHERE 



Laser 


A 


Comment 


Ionized argon 


4880 A, 5145 A 




Atomic neon (He-Ne) 


6328 A 




GaAs 


8300 A, 9200 A 


Close attention must be paid to 
temperature of operation; 
increased absorption occurs 
from approx. 8600 A to 
9250 A 


Ruby 


6934 -► 6945 A 


Strong H 2 absorptions can occur. 


Nd +3 


« 1.06 /x 


Very low absorption 


Atomic neon (He-Ne) 


1.1523 yu. 

5 lines 


Moderate H 2 absorption 


CH 4 Raman shift of 1.06 fi 


1.53 /lc 




Er +3 (CaF 2 ) 


1.55^ 1.65 fi 




(glass) 






Ho +3 -CaW0 4 


2.04 /x 


Mostly clear 


Ho +3 -YAG 


to 




Ho +3 -CaF 2 


2.128 fi 




Atomic Xe 


3.50704 fx. 




DF 


3.8 ju. 




co 2 


10.6 /x 


co 2 

Water absorption 



3 Atmospheric Transmission 41 



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0.2 0.3 0.4 0.5 0.7 I 2 3 4 

WAVELENGTH (/xm) 

Fig. 3-1. Calculated atmospheric attenuation coefficients for horizontal transmission at sea 
level in a model clear standard atmosphere. (Adapted from Reference 1.) 



42 



Handbook of Lasers 





- 












1 


' 


■ 


i 


i 

















C D /C = exp(-<r R; 

K O 

ERE, C R = APPARENT CONTRAST AT RANGE R 




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CLEAR 
















































































































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DAYLIGHT VISIBILITY RANGE R (km) 



200 



500 



Fig. 3-2. Atmospheric attenuation coefficient for visible light as a function of daylight visibility range. 



3 Atmospheric Transmission 43 



0.8 



0.6 



0.4 



0.3 



0.2 



0.1 



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0.06 — 



0.04 



0.03 



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WAVELENGTH \ (ftm) 

Fig. 3-3. Approximate variation of attenuation coefficients with wavelength at sea level for various 
atmospheric conditions (neglects absorption by water vapor and carbon dioxide). 1 



44 



Handbook of Lasers 




8 10 12 14 

ALTITUDE h (THOUSANDS OF FT) 



3 4 

ALTITUDE h (km) 



Fig. 3-4. Approximate ratio of attenuation coefficient to sea level value for slant paths 
and horizontal paths (neglects absorption by water vapor and carbon dioxide). 1 



20 









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Fig. 3-5. Contours of constant atmospheric transmittance for radiation at 0.6 /x wave- 
length in model clear standard atmosphere (visibility range 23.5 km). 1 



3 Atmospheric Transmission 45 



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1% 






















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HORIZONTAL RANGE x (km) 

Fig. 3-6. Contours of constant atmospheric transmittance for radiation at 0.28 \i wavelength in a model clear 
standard atmosphere (visibility range 23.5 km). 1 



46 Handbook of Lasers 



10 



£ 6 



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7 


2%\ 






70% 










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0.5/xm 
































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3 4 



9 10 11 12 13 14 15 



HORIZONAL RANGE x (km) 

Fig. 3-7. Contours of constant atmospheric transmittance for radiation at 0.5 [i wavelength in a model clear standard 
atmosphere (visibility range 23.5 km). 1 



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8 9 10 11 12 13 14 15 



HORIZONTAL RANGE x (km) 

Fig. 3-8. Contours of constant atmospheric transmittance for radiation at 0.6 jx wavelength in a model clear standard 
atmosphere (visibility range 23.5 km). 1 



3 Atmospheric Transmission 47 




10 11 12 13 14 15 



HORIZONTAL RANGE x (km) 
Fig. 3-9. Contours of constant atmospheric transmittance for radiation at 0.7 ju. wavelength in a model clear standard 
atmosphere (visibility range 23.5 km). 1 



10 












/ 85% 






/ e: 


t% 






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10 11 12 13 14 15 



HORIZONTAL RANGE x (km) 
Fig. 3-10. Contours of constant atmospheric transmittance for radiation at 1.06 fx wavelength in a model clear 
standard atmosphere (visibility range 23.5 km). 1 



48 Handbook of Lasers 



10 



T 6 



8 5 

i— 

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= 2.17/xm 






























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65%' 
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50%; 
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HORIZONTAL RANGE x (km) 



12 13 14 15 



Fig. 3-11. Contours of constant atmospheric transmittance for radiation at 2.17 ft wavelength in a 
model clear standard atmosphere (visibility range 23.5 km). 1 



10 



5 10* 



-3 



10 






-4 
10 

5 10 15 20 25 30 35 40 45 50 55 60 

ALTITUDE ( in thousands of feet ) 

Fig. 3-12. Average amount of precipitable water in a horizontal 
path length as a function of altitude. 2 



3 Atmospheric Transmission 49 



120 



100 



80 



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10,000 



100 1000 

PATH FOR I mm OF WATER (ft/mm) 
Fig. 3-13. Path to 1 mm of precipitable water as a function of temperature and relative humidity. 



JANUARY 





























-JULY 






\p 

















-4.0 



3.0 



-2.0 



-1.0 



in 



1.0 



2.0 



3.0 



4.0 



Fig. 3-14. The logarithm of the water vapor pressure in Torr versus altitude for average January 
and July humidities at 30°, North Latitude. 6 



50 Handbook of Lasers 



W= cm PERCIPITABLE HjO VAPOR AT SEA LEVEL 

l i i — i — r~n — i — i — i — i — r 




05 06 7 08 9 

X = WAVELENGTH ( microns ) 



W=cm PRECIPITABLE H 2 VAPOR AT SEA LEVEL 



Fig. 3-15. Calculated transmission from 0.3 to 1.0 ju, 
for precipitable water vapor concentrations of from 0.01 
to 100 cm (ref. 2). 




10 II 12 13 14 15 16 17 18 19 20 2 1 22 23 24 
X = WAVELENGTH (microns ) 

Fig. 3-16. Calculated transmission from 1 .0 to 2.4 fi 
for precipitable water vapor concentrations of from 0.01 
to 100 cm (ref. 2). 



W=em PRECIPITABLE H 2 VAPOR AT SEA LEVEL 




W = cm PRECIPITABLE HgO VAPOR AT SEA LEVEL 



24 25 26 27 28 29 30 31 32 3 3 34 35 36 3.7 38 

X= WAVELENGTH (microns) 

Fig. 3-17. Calculated transmission from 2.4 to 3.8 (jl 
for precipitable water vapor concentrations of from 0.01 
to 100 cm (ref. 2). 



1 1 1 1 1 1 1 


1 1 1 1 1 1 


W = 01 




- 1 N. 


- 


\. \ 


- 


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-1 >v \ 


^^^^ 


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; \\ 




\ 


^^ _ 


— \^ 


^>^ — 


- I I i I 1 I Ni 


i i i i rs, i - 



1 
0.01 

38 39 40 41 42 43 44 45 4.6 4.7 48 49 50 5 1 52 
X= WAVELENGTH ( microns ) 

Fig. 3-18. Calculated transmission from 3.8 to 5.2 fx. 
for precipitable water vapor concentrations of from 0.01 
to 100 cm (ref. 2). 



3 Atmospheric Transmission 51 





W = cm PRECIPITABLE H 2 VAPOR AT SEA LEVEL 




99 9 


_ I I I I I I I I I I I I 


I _ 


5 
99 


- 


- 


5 
90 


W = Ol 


- 


50 


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<\ /x 




I 
00I 


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W= cm PRECIPITABLE HgO VAPOR AT SEA LEVEL 



5 2 5 3 54 5 5 56 5 7 5 8 5 9 6 6 I 6 2 6 3 64 6 5 6.6 
X * WAVELENGTH ( microns ) 

Fig. 3-19. Calculated transmission from 5.2 to 6.6 fi 
for precipitable water vapor concentrations of from 0.01 
to 100 cm (ref. 2). 



o I 
001 



1 1 1 1 1 1 


1 1 1 1 1 1 1 _ 

W=0.0l 


- 


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- ^ 


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s 


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66 67 68 6.9 70 71 72 73 74 75 76 77 7.8 79 80 
X = WAVELENGTH (micront) 

Fig. 3-20. Calculated transmission from 6.6 to 8.0 \i 
for precipitable water vapor concentrations of from 0.01 
to 100 cm (ref. 2). 



W = cm PRECIPITABLE HjO VAPOR AT SEA LEVEL 



999 


1 


1 1 I I 


1 


5 






_ 


99 




W=0 01 


- 


5 




1 


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90 








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50 




10 


- 


10 


/ 




1 




100 


- 


001 


=/~ I ■ 


1 1 1 1 


"" — -"-»A - 



100 110 120 130 

\= WAVELENGTH ( micron* ) 



Fig. 3-21 . Calculated transmission from 8.0 to 1 5.0 //. 
for precipitable water vapor concentrations of from 0.01 
to 100 cm (ref. 2). 



52 



Handbook of Lasers 



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3 Atmospheric Transmission 125 




* > • ° 



Fig. 3-95. High resolution spectrograms of the solar spectra from .82 to 3.41 fi with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 . 



126 Handbook of Lasers 



CN 
CO 



r=V 



Fig. 3-96. High resolution spectrograms of the solar spectra from .82 to 3.41 /x with the detector at 40,000 feet 
altitude in a jet airplane. 7 ' 8 



3 Atmospheric Transmission 127 



CO 
CO 



Fig. 3-97. High resolution spectrograms of the solar spectra from .82 to 3.41 jx with the detector at 40,000 feet 
altitude in a jet airplane. 7 ' 8 



128 Handbook of Lasers 



00 




2 T <, 



r 



< 



Fig. 3-98. High resolution spectrograms of the solar spectra from .82 to 3.41 jjl with the detector at 40,000 feet 

He in a ipt airnlsne 7 > 8 



altitude in a jet airplane 



3 Atmospheric Transmission 129 





Fig. 3-99. High resolution spectrograms of the solar spectra from .82 to 3.41 ju, with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



130 Handbook of Lasers 






Fig. 3-100. High resolution spectrograms of the solar spectra from .82 to 3.41 p with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



3 Atmospheric Transmission 131 



CO 



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Fig. 3-101. High resolution spectrograms of the solar spectra from .82 to 3.41 /a with the detector at 40,000 feet 
altitude in a jet airplane. 7 ' 8 



132 Handbook of Lasers 



00 

CO 



L_-s 






Fig. 3-102. High resolution spectrograms of the solar spectra from .82 to 3.41 u with the detector at 40 000 feet 
altitude in a jet airplane. 7,8 ' 



3 Atmospheric Transmission 133 




Fig. 3-103. High resolution spectrograms of the solar spectra from .82 to 3.41 p with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



134 Handbook of Lasers 



o 

5 



Fig. 3-104. High resolution spectrograms of the solar spectra from .82 to 3.41 fx, with the detector at 40,000 feet 
altitude in a jet airplane. 7 * 8 



3 Atmospheric Transmission 135 



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Fig. 3-105. High resolution spectrograms of the solar spectra from .82 to 3.41 ju, with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



136 Handbook of Lasers 



<N 

CO 




Fig. 3-106. High resolution spectrograms of the solar spectra from .82 to 3.41 fx, with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



3 Atmospheric Transmission 137 



CO 










Fig. 3-107. High resolution spectrograms of the solar spectra from .82 to 3.41 [x, with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



138 Handbook of Lasers 




Fig. 3-108. High resolution spectrograms of the solar spectra from .82 to 3.41 (x, with the detector at 40,000 feet 
altitude in a jet airplane. 7 ' 8 



3 Atmospheric Transmission 139 



5 



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Fig. 3-109. High resolution spectrograms of the solar spectra from .82 to 3.41 //. with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



140 Handbook of Lasers 



3 






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Fig. 3-1 10. High resolution spectrograms of the solar spectra from .82 to 3.41 fx with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



3 Atmospheric Transmission 141 






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- 


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■ 


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Fig. 3-111. High resolution spectrograms of the solar spectra from .82 to 3.41 [i with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



142 Handbook of Lasers 




> : 

i 






•■^ 



■rv 

. f • 



7" 




Fig. 3-112. High resolution spectrograms of the solar spectra from .82 to 3.41 fx with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



3 Atmospheric Transmission 143 







I- 











Fig. 3-113. High resolution spectrograms of the solar spectra from .82 to 3.41 jx with the detector at 40,000 feet 
altitude in a jet airplane. 7 ' 8 



144 Handbook of Lasers 






Fig. 3-114. High resolution spectrograms of the solar spectra from .82 to 3.41 fx with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



3 Atmospheric Transmission 145 



CN 
CO 








Fig. 3-115. High resolution spectrograms of the solar spectra from .82 to 3.41 fx with the detector at 40,000 feet 
altitude in a jet airplane. 7,8 



146 



Handbook of Lasers 




uoitdjosqv 4U99J9d 

Fig. 3-116. High resolution absorption spectrum of transmission through the atmosphere from 6933 to 6946 A. 9 



3 Atmospheric Transmission 147 



D3tO 

6944 

6942 

< 

- 6940 
v> 

6 
o 

< 6938 
6936 












/ 
/ 












/ 
/ 





























































80 1 20 I60 200 240 

Degrees in Kelvin 



280 



320 



Fig. 3-117. Emission wavelength of a ruby laser as a function of laser rod temperature. 9 



0.1 



t_ 
a> 
.c 
a. 

V) 

o 

E 

< 
a. 



0.01 



0.001 



















































































































































Ca 
Lo 


Iculation from — — 
rentz Equation j 












































2 


90 K) i 












































































r^ n 


565^ 
'.-cm^J 


















P» 


















































































v — 0.17 pr.-cm. 


















0.2 1 


ii'-^P 


















pr.-< 


:m. A\ 















0.01 



10.0 



0.1 1.0 

Attenuation Coefficient/ pr .-cm. 

Fig. 3-1 1 8. Experimental attenuation coefficients at 1 . 1 52 /jl per precipitable centimeter 
vs. pressure. 9 



148 Handbook of Lasers 



10 










^^D^ 
































£l <A 






























iff 
















J^T 












to 




LEGEND 
O Experimental 
□ Calculated 




_J 




















1 












c 


) 1 





2( 


D 3 





40 50 



Per Cent Relative Humidity 

Fig. 3-119. Transmission loss at 1.152 fx vs. percent relative humidity. 9 



C 

o 



o 

eft 
-Q 

< 



c 

a 



I00°K 300°K 




25 
50 
75 



irIOO 





SpH i^sllsl 












H 2 ? 

Nd 


I02 ? i ~ 

*V -Nd* 8 : 

*0 4 CaWO 
Line (Main 
)led) — SrMo 




2 




^/ 


**~ 


Co\ 
(Main 

Cm 


4 
Line) 






V 






O4 


NO* 8 ; II 

CaW0 4 II 












Solar 





£. 10,647 50 



53 56 59 62 10,665 

Wavelength in Angstroms 

Fig. 3-120. Atmospheric absorption from 10,647 to 10,665 A, near the 10648 A Nd +3 : YAG; 10650 A Nd +3 - 
CaW0 4 ; 10650 A Nd +3 : glass; 10652 ANd +3 : CaWO*; 10652 ANd +3 : SrMoO*; and 10660 ANd +3 : CaW0 4 lasers. 9 



3 Atmospheric Transmission 149 




(S33«930) 3H9NV NOI1VA3T3 

































$$2^ 














j^NU^^* 














5 £ 


■> C 


> u 


> C 


) « 


1 o 



u> 



CM 



CD 



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o 

t- 

«D(T 
O 
</) 
ffi 

< 



(S33«930) 319NV NOI1VA313 



~ 2 

3.S 

3. CO 

OV e 
in G 

O es 

*"" 4) 

oj '^ 

C3 S 
O cu 
*3 J3 

o,+* 

O Q 

X) to 
«* fc 

as 

* 2 

it 

•is. 



E-2 



150 



Handbook of Lasers 









i 






EETE 


/I 












- ■ '" — I — cr 

! fc 











! 









g* J 

= co j ++/ 


1 . J. - 




















i 


i 
1 










































































oc 
o 






^ 

*/ 






>- I 
< l 








1 

3 






V 


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IS. / 

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in 








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> 






















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(0 tt 



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a 



CO 




u 


K 


»- 


u 


bl 


XI 


X 


u 



u 



60 



aoNvumsNVdi ivNOiiDvdd 



3 Atmospheric Transmission 151 



90 
80 


















ro 


















60 


















50 














__20% RH 




40 


















30 


















_ 20 


- 












^30 % RH 




Id 

o 


















< 












" > v >v j40%R.H. 














> S 50%R.H. 








t * 








\^0%R.H. 










5 


















4 


— 




\ \70« 


X.R.H. N. 










3 






\80%R.H. 












2 

1 



















12 16 20 

PATH LENGTH (KILOMETERS) 



24 



28 



Fig. 3-124. Calculated 10.59 fi transmittance of water vapor at 77°F in a sea level atmosphere vs. the path length 
for selected relative humidities. 10 




12 16 

PATH LENGTH ( KILOMETERS ) 



Fig. 3-125. Calculated 10.59 fi (P20) transmittance of combined carbon dioxide and water vapor at 77°F in a sea 
level atmosphere vs. the path length. 10 



152 



Handbook of Lasers 



1. 40 




350 400 450 500 550 600 650 700 

X INCIDENT WAVELENGTH (MILLIMICRON) 

Fig. 3-126. Total attenuation coefficient vs. wavelength tor collimated light in 
various water environments. 11 




500 600 

WAVELENGTH IN NANOETERS 

Fig. 3-127. Attenuation length vs. wavelength for underwater transmission of light 
in (A) distilled water, (B) oceanic coastal water, and (C) typical lake water. 12 



3 Atmospheric Transmission 153 



5.0 



4.0 - 



3.0 - 



2.0 




NOON MIDNIGHT NOON 

,, _ 8/25/66 8/26/66 

DO 



MIDNIGHT NOON 

8/27/66 



MIDNIGHT 



or 

UJ 

i- 

UJ 



o 

z 

UJ 



z 
o 

I- 
< 

Z 
UJ 



O 




MIDNIGHT NOON MIDNIGHT NOON 

9/24/66 9/25/66 



MIDNIGHT NOON 

9/26/66 



Fig. 3-128. Attenuation length around 5400 A in typical coastal waters vs. time. 11 



154 



Handbook of Lasers 



id 20 

1<J 



o 

7Z. 

UJ 

_J 

2 
O 

<x 

UJ 



I 

h- 
«1 

a. 
o 

o 

5 

O 

UJ 
K- 
*t 

_l 
_J 

o 
u 



CLEAREST __ 
OCEAN WATER 



16 



12 — 



POOR OCEAN WATER 

AND 
CLEAR COASTAL WATER 



AVERAGE 
OCEAN WATER 




AVERAGE COASTAL WATER 
POOR COASTAL WATER 

J I I 



4 !2 IS 20 24 28 

DIFFUSE (MULTIPATH) ATTENUATION LENGTH (METER) 
Fig. 3-129. Collimated vs. diffuse attenuation lengths for long path lengths in natural waters. 13 



32 



REFERENCES 



1. RCA, "Electro-Optics Handbook," RCA Corporation, 1968. 

2. T. L. Altshuler, "Infrared Transmission and Background Radiation by Clear Atmosphere," General Electric Company, 
Space Division, Space Technology Center, King of Prussia, Pennsylvania, Document No. 615D199, Dec. 1961. 

3. P. W. Kruse, L. D. McGlandlin, R. B. McQuistan, "Elements of Infrared Technology," John Wiley and Sons, 1962. 

4. H. W. Yates and J. H. Taylor, "Infrared Transmission of the Atmosphere," NRL Report 5453, U.S. Naval Research 
Laboratory, Washington, D.C. (1960). ASTIA AD 240188. 

5. M. Migeotte, L. Nevin and J. Swensson, "The Solar Spectrum from 2.8 to 23.7 Microns, Part I, Photometric Atlas," 
University of Liege, Contract AF 61 (514)-432, Phase A, Part I, Geophysics Research Directorate AFCRL, Cambridge, 
Massachusetts, ASTIA AD 210043. 

6. "Handbook of Geophysics," United States Air Force, Macmillan Company, New York, 1960. 

7. G. P. Kuiper, A. B. Thomson, L. A. Bijl, and D. C. Benner, "No. 162 Arizona NASA Atlas of Infrared Solar Spectrum 
Report VI," May 1969. 

8. D. C. Benner, G. P. Kuiper, L. Randic and A. B. Thomson, "No. 166 Arizona NASA Atlas of the Infrared Solar Spectrum 
Report X," May 1970. 

9. R. K. Long, "Atmospheric Absorption and Laser Radiation," Bulletin 199, Ohio State University. 

10. J. H. McCoy, "Atmospheric Absorption of Carbon Dioxide Laser Radiation Near Ten Microns." The Ohio State University, 
Electroscience Laboratory, Columbus, Ohio, Contract F33(615)-67-C-1949, Air Force Avionics Lab., Air Force Systems 
Command, U.S. Air Force, 1968. 

C. E. Prettyman, W. G. Swarner and G. W. Reinhardt, "Laser Propagation, The Atmosphere, Air- Water, and Underwater 
Propagation," The Ohio State University, Electroscience Laboratory, Columbus, Ohio, July 1967. 

12. E. O. Hulburt, J. Opt. Soc. Amer., 35, 698 (1945). 

13. R. B. Batelle, P. R. Gillette and R. C. Honey, "An Analysis of the Feasibility of Laser Systems for Naval Applications," 
Stanford Research Institute Project No. 2167-80, Final Report, pp. 113-126. 

14. W. L. Wolfe, "Handbook of Military Infrared Technology," Office of Naval Research, 1965. 



11 



Multilayer Dielectric Coatings 

Verne R. Costich 

Coherent Radiation 
Palo Alto, California 94303 

Coatings are characterized by reflectance versus wavelength. In the reflectance dimension, the most 
common coatings have low reflectance. They are called antireflection (AR) coatings or broadband 
antireflection (BBAR) coatings or " V " coatings to describe their performance versus wavelength. The 
second most common classification of coating has high reflectance. In this category are plain metal 
mirrors^ metal mirrors overcoated for greater durability, metal mirrors with several dielectric overlayers 
to enhance the reflection, and all-dielectric mirrors. Beamsplitters and output mirrors for lasers have inter- 
mediate values of reflectance, but must also have transmittance. In summary, most coatings are used to 
reflect very little, some to reflect very much, and a few to partially reflect and partially transmit light. 

In the wave length dimension, the three general categories are low-frequency pass (which transmits 
long wavelengths and rejects short wavelengths), high-frequency pass, and band-pass coatings. 

I shall treat these six categories of coatings first, then consider coatings for special purposes, such as 
low (or high) emittance, thermal or electric conductance, color correction, and parametric amplifiers. 

ANTIREFLECTION COATINGS 

The reflectance of a single-layer, antireflection coating is at its lowest equal to {{n\ - n^s)/ 
(«i + n^s)) 2 , where «, and n s are, respectively, the indices of refraction of the incident and substrate 
media, and « x is the index of refraction of the single layer. The ideal value for« t is (n^s)^, yielding a 
reflectance of zero. If n x is 1.10 times its ideal value, then the reflectance is 0.01, or more generally, the 
reflectance is approximately equal to the square of the fractional deviation of n x from its ideal value. 
Figure 4-1 shows the performance versus wavelength of a single layer of MgF 2 on glass in air. 




4/* 5 .6 .7 

WAVELENGTH 

Fig. 4-1 . Reflectances of single- and double-layer anti- 
reflection coats on a substrate of refractive index 1 .52. 





















u 


NCOATED 







_ 




1 
1 
1 


i 

i i 

/ 

i / 




- : / 

I B BAR / 





WAVELENGTH (/i) 

Fig. 4-2. Reflectance of a typical broadband anti- 
reflection coating. 



155 



156 



Handbook of Lasers 



The minimum reflectance of a double-layer, antireflection coating is equal to ((«i(«i) 2 — {n 2 ) 2 n^)l 
(«i( w i) 2 + (n 2 ) 2 n^)) 2 , where n x and n s are again the indices of the incident and substrate media, and 
where the n^ and n 2 are the layer indices in the order in which they are put on the substrate. Figure 4-1 
shows the performance versus wavelength of a double-layer, antireflection coating on glass in air. Note 
that the performance is better across most of the visible. The shape of the curve produced the nickname 
"V" coating for this coating. 

Broadband antireflection (BBAR) coatings are available from many suppliers, but the designs vary 
and are usually proprietary. Figure 4-2 shows the typical performance of a BBAR coating on glass in air. 
At all wavelengths between 450 and 650 nm, the reflection is below \ % and the reflection averaged over 
the same wavelength region is below 0.35%. Absorption and scattering are as much as 1.0% between 
400 and 450 nm, but above 450 nm these losses are less than \ %. 

HIGH REFLECTION COATINGS 

Figure 4-3 shows the reflection versus wavelength of a plain aluminum mirror and an aluminum 
mirror with four dielectric overlayers to enhance the reflection. The reflectance of a plain metal mirror 
is equal to ((«j — n + ify/fa + n — ik)) 2 , where n — ik is the complex index of refraction of the metal and 
n l is the index of the incident medium. The difference between the reflectance and unity is mostly ab- 
sorption. This loss may be reduced at a particular wavelength by adding a pair of dielectric overlayers, 
of one-quarter wavelength optical thickness (that is, nd = 0.25 x wavelength), putting the lower index 
layer next to the metal. This pair reduces the loss by a factor of (njn^ 2 , where n h is the higher index of 
refraction and n x is the lower index of refraction of the pair of dielectric overlayers. Adding another pair 
will again reduce the absorption loss by the same factor. As more pairs are added the losses approach 
those of an all dielectric quarter-wave stack of layers. 

Figure 4-4 depicts the reflectance frequency of an all-dielectric, quarter-wave stack on fused quartz 
in air. The example has nineteen layers of alternating high (2.35) and low (1.45) index of refraction, each 
layer being of one-quarter wavelength optical thickness. The envelope of the sideband ripples is inde- 
pendent of the number of layers ; that is, if more layer pairs were added, the envelope of the ripples would 
be the same, but their positions would be altered. The two parameters of importance for an all-die- 
lectric quarter- wave stack are the width of the high reflectance (HR) zone and the transmittance versus 
wavelength within the high reflectance zone. Figure 4-5 shows the width of the HR zone as a function of 
the ratio of the indices of refraction of the bilayers. The solid curve gives the width measured at the 
points of 50 % reflectance. The dashed curve uses a criterion more useful for laser purposes, namely the 
width at twice the minimum transmittance. The transmittance versus frequency near the tuned frequency 
is shown in Figure 4-6. The curves are symmetric about the tuned frequency; thus, only half of the HR 
zone has been shown. The numbers labelling the curves indicate the number of layers in the stack, 



? 



FRESH ALUMINUM 





-ENHANCED ALUMINUM 



DESIGN, S, (HL)*H,A 




n (S) - 1.47 
n(A) =1.00 
n(H) =2.32 
n(L) =1.45 



AAAAA 



1.5 (T 



2.O0-. 



Fig. 4-3. Reflectance of a plain 
aluminum mirror and an aluminum 
mirror with four dielectric overlayers. 



5 (T 0* o 

NORMALIZED FREQUENCY 
Fig. 4-4. Reflectance vs. frequency of a nineteen-layer all-dielectric 
quarter-wave stack on fused quartz in air. 



4 Multilayer Dielectric Coatings 157 



o REPRESENTS DATA FOR 
Ti0 2 -Si0 2 BILAYERS 




- FOR 
LASER 
PURPOSES 



iiiii 1 1 i i i i i i ii I i i i i i i i i i I 



2.0 3.0 4.0 

RATIO OF INDICES . P 

Fig. 4-5. Width of the high reflectance zone of an 
all-dielectric quarter-wave stack vs. the ratio of the 
indices of the bilayers. 




.92 .94 .96 .98 

NORMALIZED FREQUENCY 



Fig. 4-6. Transmittance vs. frequency near the 
design frequency for various numbers of dielectric 
bilayers. 



assuming the first layer on the substrate is of index 2.35, the second layer is of index 1.45, and the 
layers are alternated high and low index, each layer tuned at the same frequency. Note that the trans- 
mittance is decreased by a factor of (njn^ 2 , or 2.62 for each additional bilayer. Note also that the 
addition of a single layer decreases (increases) the transmittance by a factor of (n added ) 2 /n ,, which sim- 
plifies to (« added ) 2 in this case. That is, each layer of low index increases the transmittance by a factor of 
2.10 and each layer of high index decreases the transmittance by a factor of 5.52, which is confirmed by 
reference to Figure 4-6. 

The most often used broadband high reflector is the " cold mirror," so named because it is used on 
the reflector for a visual projection system to transmit the heat (infrared) and reflect the cold (visible) 
light. The performance of such a mirror is shown in Figure 4-7, It is made by evaporating a quarter- wave 
stack tuned in the blue on top of a quarter- wave stack tuned in the red. Since the red light has to traverse 
the blue stack twice, it shows marked absorption spikes. If a reversed design is considered, with the red 
stack on top of the blue stack, the absorption in the blue is even worse than it is in the red, in the 
example depicted. 



BEAM-SPLITTERS 

Figure 4-8 shows the performance of two common forms of beam-splitter. The dashed lines labelled 
P, O, and S, represent respectively the transmittance of a single tuned layer of index 2.35 for P polarized 
light (that is, linearly polarized light with its electric field in the plane of incidence ; the Brewster angle 
occurs for this component), for the average of the two polarizations, and for S polarized light (with its 
electric field perpendicular to the plane of incidence). The solid lines represent the same parameters for a 
four-layer beam-splitter, the first and third layer being of index 2.35, and the second and last being of 
index 1.45. Note that for unpolarized light the four-layer beam-splitter is much better. In laser systems, 
however, the S polarization is most commonly used and the single-layer beam-splitter performs better. 

To see how the performance of a beam-splitter depends on angle, one should break the analysis 
problem into two problems, one for each polarization. One can do this by replacing the optical thick- 
nesses and the indices of refraction of each of the layers with different " effective " values and also 
replacing the indices of refraction of the incident and substrate media with " effective " values. For all 



158 



Handbook of Lasers 








DESIGN S.H.A 

DESIGN S.HLHL.A 

n(S) • 1. 52 

nlH) ^2 35 

n(U ■ 1. 38 

n(A) ■ I.00 

X. ■ 0.52^ 



WAVELENGTH (Ml 

Fig. 4-7. Transmittance and reflectance of a cold 
mirror type of a broadband high reflector. 



WAVELENGTH (/I) 

Fig. 4-8. Transmittance vs. wavelength of typical 
dielectric beamsplitters. 



optical thicknesses, the effective thickness is reduced by a factor of cos(0'), where 0' is the angle of 
refraction of the light ray in the layer. The S polarization effective indices of refraction (for the massive 
media as well as for the layers) are also reduced by a factor of cos(0'). The P polarization effective indices 
on the other hand are increased by a factor of l/cos(0'). Figure 4-9 shows the variation of the effective 
indices of two materials. Note that in all cases the effective indices for the S polarization decrease mono- 
tonically with angle of incidence, while for the P polarization they increase. In fact, in this example, 
at an angle of Wjsin (0j) = 1.23, the two P polarization effective indices are identical. This is the basis 
of the MacNeille polarizing beamsplitter, whose performance is shown in Figure 4-10. The solid curves 
represent the transmittance for the P component of the incoming light, while the dashed curves represent 
the S polarization transmittance. The advantages of this type of polarizer are that it can be made more 
cheaply and with a larger clear aperture than is the case with Nicol or Glan-Thompson prisms. The 
disadvantage of a MacNeille polarizer is reduced angular acceptance and (sometimes) reduced trans- 
mittance. 




0.5 1 .0 1 .5 

n o SIN(0 o ) 

Fig. 4-9. Effective index of refraction vs. angle of 
incidence for Ti0 2 and Si0 2 at .63 jx. 




.5 6 

WAVELENGTH [fi) 



Fig. 4-10. Transmittance vs. wavelength for a 
MacNeille beamsplitting polarizer. 



4 Multilayer Dielectric Coatings 159 

Figure 4-11 shows the performance at an angle of 30° in air of the single-layer AR and the VAR 
coatings shown in Figure 4-1. 

The transmittance of a quarter-wave stack at a 45° angle of incidence as a function of layer number 
and polarization is shown in Figure 4-12. In this case the layers are all tuned at normal incidence and at 
a wavelength ten percent greater than the analysis wavelength (to compensate for the angle shift of the 
coating as the effective layer thicknesses decrease). Note that the S polarization transmittance is lower 
than (and the P polarization higher than) corresponding values in Figure 4-6. 




.5 
WAVELENGTH 



Fig. 4-11. Reflectance vs. wavelength for the single 
layer and V antireflection coatings at a 30° angle of 
incidence. 




o.oi 



34 5 6 789 10 II 
NUMBER OF COMPLETED LAYERS 

Fig. 4-12. Transmittance of beamsplitters 
at a 45° angle of incidence as a function of the 
number of bilayers. 



HIGH PASS FILTERS 

Performance of a typical high frequency pass filter is shown in Figure 4-13. The design is a quarter- 
wave stack with two eighth-wave termination layers of low index of refraction. As the number of periods 
is increased above four, the ripple envelope will remain stable, continuing to yield high transmittance 
in the high frequency region while " squaring off" the high reflectance zone. For greater bandwidth of 
rejection, another such filter tuned at a lower frequency might be put in series, sometimes even on the 
same piece of glass. 



at 0-5 




.5 (To <r - 15 ai 

NORMALIZED FREQUENCY 



2.0a o 



Fig. 4-13. Reflectance vs. frequency of a high pass filter stack of S, (L/2, H, L/2) 4 , A design. 



160 



Handbook of Lasers 



LOW PASS FILTERS 

The transmittance of a low-pass filter is shown in Figure 4-14. The design is now a quarter- wave 
stack terminated with eighth- wave layers of high index material. Again the ripple envelope is unchanged 
as more periods are added. 




& 0.5 



o _ 



0.5 (To (To l.5<To 

NORMALIZED FREQUENCY 



2.0(To 



Fig. 4-14. Reflectance vs. frequency of a low pass filter stack of S, (H/2, L, H/2) 4 , A design. 



BAND PASS FILTERS 

Figure 4-15 shows the performance of two types of bandpass filter. A single cavity filter consists of 
two regular quarter-wave stacks separated by one half-wave cavity. Similarly, the double cavity filter has 
two half-wave cavities bounded by three quarter-wave stacks. We define a shape factor to be the band- 
width at 0.01 times the peak transmittance divided by the bandwidth at 0.50 times the peak transmit- 
tance. The shape factor for a single cavity filter is nearly ten, while for a double cavity filter it is 3.5, and 
for a triple cavity filter it is 2.0, in theory at least. The rejection bandwidth is the same as the width of a 
regular quarter-wave stack's high reflectance zone, as shown in Figures 4-4 and 4-5. 



1 •") 


\\ 




! // 


iL__ DOUBLE 




/' 


•P CAVITY 




M FILTER 




! I' 
I 


\\ 






' / 


\\ 






/ 


.1\ 


, SINGLE 




: CAVITY 


/ / 




\ FILTER 


i I 


\ \ 1 


i i 


\ \ ' 


/ \ 


\ \ ; 


i / / 


\ S 






\ N 


/ 




\ \ 


/ 




\ \ 


/ 




\ N 


/ 


1 




\ V 


i 











.97 .98 .99 100 Oj, 1.01 1.02 103 

NORMALIZED FREQUENCY 



— -■ 










\ 
\ 








1 

V 
1 
1 


\ 


\y 

i 
i 

1 : 






HIG 


/ 

i REFLEC 

/ 
y 


roR 



.5 .6 .7 

WAVELENGTH </i) 



Fig. 4-15. Transmittance vs. frequency of single 
cavity and double cavity band pass filters. 



Fig. 4-16. Transmittance vs. wavelength for various 
broadband mirrors in the visible. 



4 Multilayer Dielectric Coatings 161 



MISCELLANEOUS COATINGS 



The coatings shown in Figures 4-16 through 4-24 are self-explanatory except for these comments: 
The ultraviolet laser mirror in Figure 4-17 used materials that are highly absorbing below 260 nano- 
meters ; therefore it cannot be shifted to even shorter wavelengths. The conductive coating in Figure 4-20 
was measured to have 25 ohms per square. 






1 

H 






f'ii 


1 
1 
I 
1 






i 
l 

1 


i! 

» 


1 
1 
1 
1 
1 
1 
1 
1 










1 
-t 

1 

1 

1 

1 

1 
~\ 

1 

1 

1 

1 


Z.I3/» 






V 

v 


11 ^ 



WAVELENGTH (/*) 



1.0 1.4 1.8 

WAVELENGTH (M) 



Fig. 4-17. Transmittance vs. wavelength for UV 
laser mirror or UV reflection filter. 



Fig. 4-18. Transmittance vs. wavelength for typical 
parametric amplifier coating. 





N . 

\ 
\ 
\ 




j 

j 

r 


■■ 


'" 


\_ 


r 

i 







1 






WAVELENGTH (p) 



.5 .6 

WAVELENGTH (/») 



Fig. 4-19. Transmittance vs. wavelength for typical 
color correction (tungsten-daylight) filter. 



Fig. 4-20. Transmittance vs. wavelength for con- 
ductive coating of 25 O per square. 



162 



Handbook of Lasers 



t 
1 

BLUE W 


\ 

II / \ 

1M / K 


.1 / 

SS DICHROIC I 
_ I 1. i J 






• i r ■ 1 

, i i 

1 i 

M 


DPASS 01 


:hroic 


] IRE 
1 1 

i 1 1 

: 1 1 

1/ 

1 | 





.5 .6 7 

WAVELENGTH (p) 













i 
1 












1 
1 








10 X j 

1 
1 












1 
1 

!i 

1 1 

I 1 

i 1 1 










100 X | J 1 

! " / 

" 

1 ji 

20 



WAVELENGTH <p) 



Fig. 4-21. Transmittance vs. 
pass and red pass dichroic filters. 



wavelength for blue 



Fig. 4-22. Transmittance vs. wavelength for low 
frequency pass filter. 





» V 


y\A 


i 












/! 






— 


If! 
i 

i 
i 

1 
1 
1 
1 
1 
1 
'~l 
1 













1 
1 
1 

1- 

1 
1 
1 
1 


y-.694 


¥■ 








1 


/ 













I 5145 


* 












II 

II 














!i/ 






— 








i 

— 


— 






1 

i 


—I 

1 

"J 

1 

1 










.4880/1 


1 
1 
/ 



.5 .6 .7 

WAVELENGTH (/* ] 



.5 .6 

WAVELENGTH I/O 



Fig. 4-23. Transmittance vs. wavelength for ruby- 
laser eye protector. 



Fig. 4-24. Transmittance vs. wavelength for argon 
laser line discriminator. 



COATINGS FOR 1, 2, AND 3 WAVELENGTHS 

For people doing parametric amplifier work or second harmonic generation it is necessary that 
coating performance be known over wide frequency ranges. Therefore, at the risk of repetition, I will 
discuss four categories of coating used in this field : 

1. coatings that operate at only one wavelength; 

2. coatings for laser wavelength suppression, to operate at one transition and suppress operation 
at another; 

3. coatings to operate at both the pump and the second harmonic frequency; 

4. coatings to operate at pump, signal, and idler frequencies. 



4 Multilayer Dielectric Coatings 163 

LASER MIRRORS AND ANTIREFLECTION COATINGS 

A laser cavity is usually made up of mirrors coated with many quarter-wave thick layers of materials 
having alternating high and low indices of refraction. The stack generally starts and ends with a high- 
index layer. 

Figure 4-25- shows the performance of a laser coating as a function of wavelength. Note the linear 
frequency scale at the top of the figure, with a designating the tuned frequency. The performance of 
coatings made up of only quarter-wave optical thickness layers is symmetrical on a linear frequency 
scale. However, since most references are made to the performance at particular wave lengths, the 
scale on the axis is labeled in wavelengths. The width of the region of high reflection can be defined by 
the points at which the transmittance is equal to twice its minimum value. For the mirror in the figure 
this band-width is 60 nanometers or about 10% of the laser wavelength. 

Losses from absorption and scattering may amount to less than 0.2%. If one uses only coatings 
ending in high-index layers, the transmittances indicated in Table 4-1 will be obtained. Use of other 
designs will yield intermediate transmittances. Only odd integral numbers of layers are used. 

Antireflection coatings on glass surfaces used in laser systems may be either a single layer of MgF 2 
or a double layer coating of A1 2 3 and MgF 2 . The performances of both these coatings are shown in 



RELATIVE FREQUENCY 



Ui 

o 

z 



V) 

z 



Q 
Id 
(Z 

3 
V) 
< 
UJ 




I..8Q-, 



2.00J 



2£<r. 



3.p<r, 



DESIGN- S, (HLfH, A 

S- FUSED QUARTZ 

H-TlOg 

L-SiO c 

A- AIR 

X« 633 nm 



—I 1 

Q6x, Q5x, 



0.4*. 



0.3k. 



RELATIVE WAVELENGTH 

Fig. 4-25. Transmittance of high reflectance laser coating as a function of wavelength. 



TABLE 4-1. PERCENT TRANSMISSION OF 
MULTILAYERS OF Ti0 2 AND Si0 2 

Both First and Second Layers Are Ti0 2 



n 


500nm 


633nm 


694nm 


1060nm 


H52nm 


1 


64.0 


67.0 


68.0 


69.0 


70.0 


3 


34.0 


34.0 


35.0 


37.0 


38.0 


5 


12.0 


14.0 


15.0 


18.5 


19.0 


7 


4.3 


6.1 


6.2 


8.2 


8.5 


9 


1.6 


2.4 


2.4 


3.5 


3.7 


11 


0.6 


0.9 


1.0 


1.5 


1.6 


13 


0.2 


0.4 


0.4 


0.6 


0.6 


15 


0.06 


0.1 


0.1 


0.2 


0.2 


17 


0.02 


0.03 


0.04 


0.06 


0.07 


19 


0.01 


0.01 


0.01 


0.02 


0.02 



164 



Handbook of Lasers 



RELATIVE FREQUENCY 





0.05 
0.04 




5o- 


o"o I5cr 


20 a 2.5ct 


300^ 


UJ 

o 


-^^- 


1 
• 


i 1 

r ; 


i 1 


1 


*£ 








\ / 






< 












III • 


0.03 






• '7 


DESIGNS ; 




_l 






b,L,A 


— 


Ul 
UJ 








i \ / / 


S.ML.A 




cc 


0.02 






V / / 


S,A 




Ul 








\ // 


S= 152 INDEX GLASS 


or 

-> 










L = MgF 2 




CO 

< 


001 






\ / 


M=AL 2 3 




UJ 

2 


00 


II 1 


1 


\ / 
\ / 

VI 1 1 1 


A=AIR 
Ao = G33 nm 





5X 2X X 08X 06X 0.5X 0.4X 0.3X 

RELATIVE WAVELENGTH 
Fig. 4-26. Transmittance of a typical antireflection coating of MgF 2 or Al 2 3 -MgF 2 as a function of wavelength. 



Figure 4-26. Typically their absorption and scattering is 0.1 %. The purpose of each coating is to increase 
the transmittance of a system and/or reduce the effect of ghost images, which often cause undesirable 
interference-fringe patterns in coherent light systems. These same coatings can be put on ADP or KDP 
crystals, to be used in modulators or frequency doublers. Because of difficulties in polishing and cleaning 
water-soluble crystals and restriction on heat during coating, they usually have scatter and absorption of 
0.5%. 

A single layer of either ThF 4 or Si0 2 makes a good antireflection coating on either LiNb0 3 or 
BaNaNb0 3 crystals, as shown in Figure 4-27. The Si0 2 coating can be cleaned without scratching; it is 
insensitive to heat from a phase-matching oven, but typically produces no lower than 0.2% reflection, 
while the ThF 4 produces reflection lower than 0.1 %. If the Si0 2 coating should have to be removed, it 
must be polished off, but ThF 4 can be washed off in water. 

The performance of a beam-splitter depends on the polarization of the incident beam and the angle 

RELATIVE FREQUENCY 




0.4 x. 



RELATIVE WAVELENGTH 
Fig. 4-27. Transmittance vs. wavelength of a single layer coating of ThF* on Si0 2 on LiNb0 3 



4 Multilayer Dielectric Coatings 165 



RELATIVE FREQUENCY 



UJ 

o 

z 
.< 



co 

z 
< 



Q 
UJ 
OC 

CO 

< 
UJ 



i.o 

0.9 H 
0.8 
0.7 - 
0.6 - 
0.5 
0.4 - 
0.3 - 
0.2 - 
O.I - 
0.0 



,5ci 
_l 



l.5oi 



2.0<r. 



2.5<r, 



3.0 a. 




S, H,A 



S,(HUTA 



S - FUSED QUARTZ 
H ■ Ti Oj 
L ■ SI 0, 
A • AIR 
X.* 700nm 



ill I — 
5* ( 2 k, 



T— 1 1 1 1 1 

x. 0.8k Q 0.6 k # 0.5 k 



0.3 k, 



RELATIVE WAVELENGTH 

Fig. 4-28. Performance of typical beam splitters as a function of wavelength and polarization. 



of incidence. Figure 4-28 shows the typical performance of two types of beam-splitters operating at 45°. 
Curve P is for the case when the electric field of the light is parallel to the plane of incidence, as when a 
gas laser is used and the beam-splitter is roughly parallel to the Brewster-angle windows. 

When a laser's active medium exhibits two closely spaced competing transitions, the mirror coatings 
can suppress the oscillation of one. The transmittance of such a mirror is shown in Figure 4-29. This 
mirror suppressed oscillation of a YAG laser at 1060 nm, while lasing at 946 nm. Losses at 946 nm were 
less than 0.3%. The reflectance at 1.06 microns cannot reasonably be reduced below 5%, because a 
large number of layers are required to obtain the high reflection at 946 nm. Indeed, whenever a coating 
must be highly reflecting at one wavelength and highly transmitting at another, transmittances above 
95 % are rare, computer results notwithstanding. 

RELATIVE FREQUENCY 



UJ 




o 

z 


0.9 - 


ft 




\- 


0.8 - 


h- 




2 


0.7 - 


CO 




z 


0.6 - 


< 




ac 


0.5 - 


t- 






0.4 - 


Q 




UJ 

or 


0.3 - 


3 




CO 


0.2 - 


12 


0.1 - 


i 


0.0 - 



»°1 



1.50". 




DESIGN: S, I.I H 1.1 l(j Ly),A 

S • FUSED QUARTZ 
H ■ Ti t 
L - Si t 
A - AIR 
K m 900 nm 



5x. 



f— r 



RELATIVE WAVELENGTH 

Fig. 4-29. Transmittance vs. wavelength of 1.06 p transition suppressing laser reflector. 



166 



Handbook of Lasers 



RELATIVE FREQUENCY 



o 

z 
< 



CO 

z 
< 
or 



Q 
UJ 

ac 

CO 

< 

UJ 



i.o 

0.9 - 
0.8 - 
0.7 - 
0.6 
0.5 
0.4 
0.3 - 
0.2 - 
O.I - 
0.0 



.50-. 0", 



I5<r. 



2.00-. 



\ 



LL 



DESIGN S, {Hl_f H, A 



S ■ FUSED QUARTZ 
H « Ti Og 
L • Si0 2 
A • AIR 
X." 560nm 



2x. 



0.8 x. 0.6 x 8 0.5x. 



0.4x, 



0.3 x. 



RELATIVE WAVELENGTH 

Fig. 4-30. Transmittance vs. wavelength of a wavelength suppressing 
mirror for Argon II allowing only 515-nm output. 

Another example of wavelength suppression by coatings is shown in Figure 4-30. This coating 
allows an argon laser, without an intracavity prism, to produce 515-nm output only. Similar coatings 
have been used to make a helium-neon laser work at 730 nm only, or at 1.06 microns only. 

Figure 4-31 shows the transmittance of such a coating, which was used to make a helium-neon 
laser operate simultaneously at 633 nm and 1.15 microns. The antireflection coating for this laser is 
shown in Figure 4-32. 

High transmittance at the doubled frequency can be attained, as shown in Figure 4-33. This coating 
was used to double 515 nm, using an antireflection-coated ADP crystal. To retain high transmittance 
(low absorption) in the ultraviolet, A1 2 3 was used as the high-index material. Therefore, 75 layers were 
used to obtain the high green reflection. 



RELATIVE FREQUENCY 



o 

z 

CO 

z 
< 

DC 

I- 



or 

CO 

< 

UJ 



1.0 

0.9 

0.8 

0.7 

0.6 

0.5 - 

0.4 - 

0.3 

0.2 

0.1 

0.0 



2.0<r o 



2.5<r. 



I I0X| 




DESIGN: S, (*£■ -y) 4* ,A 



|I0X| 



S » FUSED QUARTZ 
H - Ti t 
L ■ Si t 
A • AIR 
X - l.24yu 



2x. 



0.6 x, 0.5 x„ 



0.4 x. 



RELATIVE WAVELENGTH 
Fig. 4-31. Transmittance vs. wavelength for a laser coating of high reflection at .63 /x and 1.15 /jl. 



4 Multilayer Dielectric Coatings 167 

RELATIVE FREQUENCY 



UJ 

o 

z 

O 
UJ 



or 



0.03- 



Q ° 02 

UJ 

Z> 

(A) 0.0I - 

< 

Ul 



l.5oi 2.0oi 2.5oj 3.0o; 




DESIGN: S.LMML.A 

S- FUSED QUARTZ 
L * Mg F 2 
M-AljO, 
A- AIR 
\* 900 nm 



5k. 2 k, k. 0.8 k. 0.6).. 0.5k, 0.4 x. 



0.3 k, 



RELATIVE WAVELENGTH 

Fig. 4-32. Transmittance vs. wavelength of an antireflection coating for .63 /x. and 1.15 /x. 

RELATIVE FREQUENCY 



UJ 


1.0 


o 




z 


0.9 


< 




H 


0.8 


h- 




5 


0.7 


<o 




z 


0.6 


< 






0.5 




0.4 


Q 




Ul 


0.3 


3 




CO 


0.2 


< 




Ul 


0. 1 


2 






0.0 



5<r. 



l.5oj 



2.0<r, 



2.5o; 3.0«r, 




DESIGN: S, (ML) M, A 

S • FUSED QUARTZ 

M ■ AlgOj 

L - Si 2 

A • AIR 

X, « 5l5nm 



T - ! — i 1 1 1 — 

k. 0.8k. 0.6k. 0.5k 



RELATIVE WAVELENGTH 

Fig. 4-33. Transmittance vs. wavelength for a coating having high reflectivity at A and high transmittance at 0.5 A . 

Scatter, which increases with the number of layers, was a problem. Also, with such low mismatch 
between high and low indices of refraction, the bandwidth of the high reflectance region is very narrow. 
This means a reduced initial yield, and any shift of the coatings with age will result in noticeable de- 
gradation. 



COATINGS FOR PARAMETRIC AMPLIFIERS 

The mirrors shown in Figure 4-34 were used to construct a continuous-wave parametric oscillator 
with a 515 nm pump and with signal-idler beams at 685 nm/2.06 microns. Both regions of high reflection 
have low absorption and scattering. Note that they are of equal width on a linear frequency scale. The 
nonlinear lithium niobate crystal used was coated to exhibit low reflection at 685 nm and 2.06 microns, 
while having reasonable transmittance at 515 nm. Its reflectance is shown in Figure 4-27. 



168 



Handbook of Lasers 



UJ 

o 

z 

V) 

z 
< 

\- 

Q 
UJ 

q: 

to 

< 

UJ 



I.O 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 - 

O.I 

0.0 



RELATIVE FREQUENCY 



25 05 




S ■ FUSED QUARTZ 

H • Ti0 e 

L • Si0 c 

A ■ AIR 

\- 2.0 \ji 



I0X 




u 



x 0.8 x, 0.6x. 0.5 x. 0.4x, 0.3x, 0.25 x # 

RELATIVE WAVELENGTH 

Fig. 4-34. Transmittance vs. wavelength for a reflector with high reflectance 
at 2.06 /a and .685 [i. and with high transmittance at .515 \l. 

SUMMARY OF 14 TYPES 

All coatings discussed have been divided by wavelength into four categories operating at : a single 
wavelength, two wavelengths in the ratio 1.5 to 1.0, two wavelengths in the ratio 2.0 to 1.0, and two 
wavelengths in ratio 3.0 to 1.0. 

With respect to reflectance, there are four natural categories : highly reflecting at both wavelengths, 
anti-reflecting at both wavelengths, highly reflecting at the longer wavelength and anti-reflecting at the 
shorter wavelength, and anti-reflecting at the longer wavelength and highly reflecting at the shorter 
wavelength. 

One would expect 16 categories of coatings in a 4-by-4 array. Table 4-2 shows the performance of 
14 types of coatings; two would-be members of the array being meaningless. This table gives the specifi- 
cations that could be met, and the ease of production of the coating. 

Five of these coating types have not yet been discussed. Two of them, Figures 4-35 and 4-36, are 
often used in nonlaser visual systems under the names " broadband antireflection coating " and " cold 

RELATIVE FREQUENCY 



2.0tr, 



UJ 
O 



O 

UJ 



Q 
UJ 

oa 

■=> 

< 




2.5cr 



30(r, 



DESIGN : 


S, M2HL 


A 


s ■ 


FUSED 


QUARTZ 


M • 


A'*0, 




H ■ 


Zr Z 




L - 


MgF, 




A • 


AIR 




K' 


735 nm 





0.4x 



RELATIVE WAVELENGTH 
Fig. 4-35. Reflectance vs. wavelength of a broad-band, high-reflectance coating. 



4 Multilayer Dielectric Coatings 169 

TABLE 4-2. PERFORMANCE AND EASE OF FABRICATION 
DATA ON 14 CATEGORIES OF DIELECTRIC STACKS 



N. R 


HR 


AR 


HR long 


AR long 


X \v 


both 


both 


AR short 


HR short 






Easy 


\ / 


\ / 


1.0 : 1.0 


Easy 

R» 99.8 

A<0.2 


R-c0.2 
A-cO.1 
T»99.7 


A 


A 




Medium 


Easy 


Medium 


Medium 


1.5 :1.0 


R > 99.6 


R<0.5 


AQ1.5X« 0.2 


A(5D X -c 0.2 




A<0.4 


A*0.1 


T® Xs-90. 


T®1.5X>90. 




Difficult 


Very Difficult 








R » 99.7 


R-c 1.0 


Easy 


Easy 


2.0 : 1.0 


at both 


at both 


A(aD2.0X< 0.2 


A®X< 0.2 




A* 0.3 


A^O.I 


T@X»90. 


T@ 2.0X^90. 




at both 


at both 








Easy 


Easy 








R > 99.8 


R -=02 


Difficult 


Easy 


3.0:1.0 


at both 


at ooth 


A (3) 3 0X<0.2 


A(8>X< 0.2 




A-c 0.2 


A< 0.1 


TCD X»90 


T@3.0X>90. 




at both 


at both 







mirror coating " respectively. It should be noted that cold mirrors usually have absorption spikes that 
are not evident in transmission curves. Broadband high reflectors for laser systems, such as krypton 
lasers, might be allowed absorption spikes, if they can be placed " between the lines." However, if a 
broadband high reflector is to be used in a parametric amplifier, it should have uniformly low loss. 

Two other coating types (Figures 4-37) are minor modifications of the design of a standard laser 
high reflector to increase the transmittance at longer wavelengths. The last coating type is highly trans- 
mitting at one wavelength and highly reflecting at triple that wavelength. The coating shown in Figure 4-3 1 
has high reflection at A and high transmission at 0.33/l , but is difficult to produce with low losses at 
the shorter wavelength. 

The 14 types of coatings described are characterized by their reflectance (transmittance) at their 
wavelength(s) of operation. All of these types have been made, and most of them have been used in 
lasers, harmonic doublers, or parametric amplifiers. 

The most natural designs are those that are to operate at only one wavelength, or identically at a 
3 to 1 ratio of wavelengths, with high reflection or antireflection at both wavelengths. These types yield 
very low losses. Mixed requirements — high reflection at one wavelength and high transmission at 
another — are less satisfactory. The losses in the high-reflection region remain low, but it is very difficult 
to reduce the reflection below 5 % in the region that is to be highly transmitting. 



170 



Handbook of Lasers 



RELATIVE FREQUENCY 



2 

H 



V) 



< 



a 

UJ 

a: 
cn 

i3 





.So-, 


oi 'So, 


2.0oi 2.50. 3.00, 






0.9 - 
0.8 - 


f/m 


DESIGN: S, 0.68h(j L -j) 


0.7 " 


\1 


(032H0.65L0.32Hf, A 


0.6 " 




f S • FUSED QUARTZ 
. J H » TiOg 


0.5 ■ 




A 1 L • SiOt 
. l\ I A • AIR 


0.4 - 


1 1 


f X.« 6IOnm 


0.3 " 


M 




0.2 " 






0.1 - 


v> 


o.o -1 


1 m 1 


I—I — 1 1 


I 1 1 1 



5k, 2k, 



x, 0.6k, 0.6k, O.Sk, 



0.4 k, 



0.3 k, 



RELATIVE WAVELENGTH 

Fig. 4-36. Transmittance vs. wavelength of a "cold mirror" coating. 

RELATIVE FREQUENCY 



UJ 

o 



2 



z 
< 
ac 



3 

< 

UJ 



.9 


o. 


0, l.5<r. iOo, 


2.50, 


3.0o. 




3.50J 4 


0.9 - 












0.8 - 












0.7 - 
0.6 - 




DESIGN: s, (7 -J 7) L. A 










0.5 - 
0.4 - 




S • LITHIUM NIOBATE 
H ■ Tl O t 
L • Si Ot 
A • AIR 








I 




0.3 - 




X.- I.72ju 








M 




0.2 - 








1 IOX 


1 




0.1 - 
0.0 - 








V 


J 





2x. 



k, 0.8 x, 0.6 x. 0.5x. 



0.4 k. 



0.3 k, 



0.25 k. 



RELATIVE WAVELENGTH 

Fig. 4-37. Transmittance vs. wavelength of a dielectric coating with enhanced 
transmittance at A and high reflectance at 3 A . 



REFERENCE 

Figures 4-25 through 4-37 and Tables 4-1 and 4-2 by courtesy of Laser Focus, Nov. 1969. 



Optical Detectors 



Donald E. Bode 

Santa Barbara Research Center 

{Subsidiary of Hughes Aircraft Company) 

Goleta, California 93017 



This chapter contains characteristic parameter curves for currently available photodetectors. More 
complete details of their performance and limiting characteristics are covered in an excellent review 
article by Melchior, Fisher and Arams. 1 

Figure 5-1 is the wavelength dependence of the absolute sensitivity (responsivity) and quantum 
efficiency for commercially available photoemissive surfaces. Several new photoemitters, 1 not shown on 
the figure, with negative electron affinity have improved infrared response, and are of particular im- 
portance for use with Nd 3 + lasers. 

Table 5-1 lists the typical and best responsivities for the more important surfaces at the emission 
wavelengths of the ruby, GaAs and Nd 3+ lasers. It also tabulates the dark current at room temperature 
for these various surfaces. 



TABLE 5-1. RADIANT SENSITIVITIES AND DARK CURRENTS OF 
SELECTED PHOTOEMISSIVE SURFACES 





Radiant sensitivity, mA\W 


Dark current 


Cathode 


Typical (best) 




at room temperature 




694nm 


860nm 


1060nm 


A/cm 2 


e/cm 2 sec 


GaAs-P 


30 






3x 10- 15 


2x 10 4 


S-20 


20 


0.5 




3 x 10~ 16 


2x 10 3 


ERMA 


26, (40) 


10 (21) 




1 x 10~ 15 


6x 10 3 


S-l 


2 


2.5 (3.5) 


0.4, (0.9) 


9x 10- 13 


6x 10 6 


GaAs 


28, (72) 


12.5, (57.5) 




3 x 10- 14 


2x 10 5 


GalnAs 






4.3, (8.6) 


3 x 10- 14 


2x 10 5 


(photocathode only) 












BiAlkali 








1-6 x lO" 18 


1 x 10 1 


S-22 













At wavelengths longer than those at which photoemissive surfaces respond, it is necessary to use 
internal photoeffects. Figures 5-2 and 5-3 show the spectral dependence of the detectivity (D*) for 
various photoconductive detectors. D* is a figure of merit in units of cm Hz 1/2 W" 1 and is normalized 
to a one-cm 2 detector and a one-Hz bandwidth. Figure 5-4 gives the spectral dependence for various 
photovoltaic detectors. Table 5.2 summarizes this D* and NEP data and includes characteristic time 
constants. Figure 5-5 indicates the spectrally flat D* performance of pyroelectric detectors, thermo- 
couples and thermopiles. The D* values for many of the cooled detectors are limited by the ambient 
background radiation incident on the detector element. Figure 5-6 shows the improvement that can be 
achieved by cold radiation shielding. Figures 5-2 to 5-5 are for a 60° field of view. Figure 5-7 indicates the 
temperature dependence of the detectivity of various detectors and Figure 5-8 gives the spectral de- 
pendence of the responsivity of silicon photodiodes of varying fabrication. 

171 



172 



Handbook of Lasers 



TABLE 5-2. TYPICAL PHOTODETECTOR PARAMETERS 



Detector 
Material 



Si 



Ge 



PbS 

PbS 

PbS 

PbSe 

PbSe 

PbSe 

InAs 
InAs 
InAs 
InSb 
InSb 

Ge:Au 



Mode 



Operating 
Temperature 



PC 



Hg . 8 Cdo. 2 Te PV 



Recommended 

Spectral 

Range 

(ju,m) 



Spectral 
Peak 
(fxm) 



Detectivity range 
D*(\m,fm) 
(cm Hz 112 watt' 1 ) 



Time 
Constant 

Range 
(Seconds) 



295 



253 



PC 


295 


PC 


193 


PC 


77 


PC 


295 


PC 


193 


PC 


77 


PV 


295 


PV 


193 


PV 


77 


PV 


77 


PC 


77 



77 



Ge:Hg 


PC 


<28 


Ge:Cd 


PC 


<21 


Ge:Cu 


PC 


<15 


Ge:Zn 


PC 


<12 


Hg0.sCdo.2Te 


PC 


77 



77 



0.4 to 1.1 



0.9 to 1.5 



1.0 to 3.0 
1.0 to 3.5 
1.0 to 4.0 
1.0 to 4.5 
1.0 to 5.1 
1.0 to 6.5 

1.0 to 3.6 
1.0 to 3.4 
1.0 to 3.1 
2.0 to 5.4 
2.0 to 5.4 

2.0 to 7.0 



2.0 to 13.* 
2.0 to 23 
2.0 to 28 
2.0 to 38 

8.0 to 13 



8.0 to 13 



0.9 



1.5 



2.4 
2.7 
3.2 
3.7 
4.4 
5.0 

3.5 
3.3 
3.0 
5.3 
5.3 

5.0 



11.0 
22.0 
24.0 
35.0 



1 x 10- 8 



3x 10- 9 



0.7 to 1.5 x 10 11 
2.0 to 7.0 x 10 11 
0.8 to 2.0 x 10" 
0.3 to 1.2 x 10 10 
1.5 to 4.0 x 10 10 
1.0 to 3.0 x 10 10 

0.25 to 1.3 x 10 10 
0.4 to 3.0 x 10" 
3.0 to 8.0 x 10" 
0.5 to 1.1 x 10" 
2.5 to 5.0 x 10 10 



1 to 5 x lO" 4 
5x lO" 3 
3x lO" 3 
2x lO" 6 
3x 10" 5 
4x lO" 5 

RC 
RC 
RC 
RC 

5x lO" 6 



3.0 to 6.0 x 10 9 0.2 to 5 x 10" 8 



0.7 to 1.5 x 10 10 
0.7 to 1.5 x 10 10 
0.7 to 1.5 x 10 10 
0.7 to 1.5 x 10 10 



12 ±1 2to6xl0 9 



12 ±1 3to9xl0 9 



1 to7x 10- 8 
1 to7x 10" 8 
1 to7x lO" 8 
1 to5x lO" 8 

1 to 3 x lO" 7 



RC 



Remarks 



NEP** = 5 
x 10~ 14 
W/Hz 1/2 with 
preamp 

NEP = 0.5 
-l.Ox 10" 12 
W/Hz 1/2 with 
preamp 



C « 100 to 300 
pf/mm 2 



D*(lQ.6fx) 
~ 10 7 cm 
Hz 1/2 watt- x 

Time constants 
below 1 nano- 
second are 
possible 

Time constants 
of 10" 8 sec- 
onds possible 
with lower D* 

Can be less than 
5 nano- 
seconds 



CODE: 

A — Avalanche Diode 
PC — Photoconductive 
PV— Photovoltaic 



NOTE: D* values reported when looking at a 295°K background with a 2tt steradian field 
of view, and the detector used under optimum electrical load. A mismatch of de- 
tector to load can result in a lower D*. A reduced effective background condition 
can improve D*. 
** Noise equivalent power. 



5 Optical Detectors 173 




I000 2000 3000 4000 5000 6000 7000 8000 9000 10,000 11,000 12,000 

WAVE LENGTH -ANGSTROMS 
I I I I I I I I I I 1 1 



12.4 6.2 4.13 3.1 2.48 2.07 1.77 1.55 1.38 

PHOTOELECTRIC ENERGY- tV 



24 



1.13 1.02 



Fig. 5-1. Absolute sensitivity vs. wavelength for photoemissive surfaces available in commercial tubes. 



174 Handbook of Lasers 



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WAVELENGTH (microns) 



Fig. 5-2. D*(A) as a function of wavelength for lead sulfide- and lead selenide-type photoconductive detectors. 
(Courtesy of Hughes Aircraft Co.) 



5 Optical Detectors 175 




.4 .5 .6 .7.8. 9ID I.5 2.0 2.5 3 4 5 6 7 8 9 10 \5 20 25 30 

WAVELENGTH (microns) 

Fig. 5-3. D*(A) as a function of wavelength for various photoconductive detectors. (Courtesy of Hughes Aircraft Co.) 



176 Handbook of Lasers 







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.4 .5 .6 .7.8910 1.5 2.0 2.5 3 4 5 6 7 89 10 15 20 25 30 

WAVELENGTH (microns) 

Fig. 5-4. D*(A) as a function of wavelength for various photovoltaic detectors. (Courtesy of Hughes Aircraft Co.) 



5 Optical Detectors 177 



13 



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12 



10 



II 



~ 2 

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° 10 

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.4 .5 .6 .7.8.9 ID I.5 2.0 2.5 3 4 5 6 789I0 \5 20 25 30 

WAVELENGTH (microns) 

Fig. 5-5. D*(A) for thermal detectors. 



178 



Handbook of Lasers 



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— 




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9 (DEGREES) 



140 



Fig. 5-6. Theoretical improvement in D* for reduced fields of view. (Courtesy of Hughes Air- 
craft Co.) 



LIQUID 
,2 .HELIUM 



FREON 
14 



E 



~ 10 




20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 
DETECTOR TEMPERATURE (DEGREES KELVIN) 



Fig. 5-7. Temperature dependence of D* for various detectors. 



5 Optical Detectors 179 




20 .25 .30 .35 40 45 .50 .55 .60 .65 .70 .75 .80 85 90 .95 



Fig. 5-8. Responsivity vs. wavelength of silicon junction photodetectors 
of various types. (Courtesy of United Detector Technology, Inc., Santa 
Monica, California.) 



REFERENCE 

1. H. Melchior, M. Fisher and F. Arams, Proc. IEEE, 58, 1466-1486, 1970. 



Section 3 

Coherent Optical Sources 



Page 

183 Neutral Gas Lasers 

242 Ionized Gas Lasers 

298 Molecular Gas Lasers 

350 Dye Lasers 

355 Rare Earth Liquid Lasers 

360 Commercial Laser Glasses 

365 Injection Lasers 

371 Insulating Crystal Lasers 



Neutral Gas Lasers 



Colin S. Willett 

Harry Diamond Laboratories 
Washington, D.C. 20438 



INTRODUCTION 

Since the first report in 1961 of population inversion and oscillation in a gas discharge in a helium- 
neon mixture, oscillation in 29 elements on more than 450 identified transitions in neutral species has 
been reported. Figure 6-1 shows that oscillation in neutral species has been observed in all atomic groups. 

Neutral gas lasers fit into three broad classifications depending on the types of electrical excitation 
used. These types of excitation are: 

1 . Weakly ionized dc and rf-excited discharges. 

2. Pulsed afterglow discharges. 

3. Short rise-time pulsed discharges. 

Weakly Ionized DC and RF-Excited Discharges 

The most commonly used CW laser medium for neutral species is the weakly ionized plasma of the 
positive column of the glow discharge. The current densities involved in such discharges in which CW- 
oscillation has been reported are typically 100-200 mA/cm 2 . The properties of the plasma of the positive 
column are determined by the electric field existing along the column. In a steady, unstriated, uniform 
positive column the longitudinal electric field has such a value that the number of electrons and ions 
produced is equal to the diffusion loss of charged particles to the walls of the discharge tube. The electron 
temperature in the plasma adjusts itself to that value required to maintain the flow of positive ions and 
the loss of electrons to the walls. A theoretical treatment of the positive column in gases 202 and gas- 
mixtures, 206 where volume-ionization and electron-metastable collisions are not significant, leads to the 
important result that the average electron temperature is determined primarily by the pressure and tube- 
diameter product (pD). A low pD results in a high electron temperature, and a high pD in a low electron 
temperature (see Ref. 203). To reproduce given discharge conditions in a discharge in a single gas, all 
that is necessary is that the pD be maintained constant (at constant electron concentration). In the 
weakly ionized plasma of the positive column the electron concentration is directly proportional to the 
current density. 

Because of the basic importance of the pD-product in laser discharges in single gases or mixtures 
of gases, the following tables include values of the optimum pD for giving population inversion on a 
large number of transitions. 

Pulsed Afterglow Discharges 

Pulsed afterglow discharges were first used by Boot, Clunie and Thorn 133 to give laser oscillation in 
neutral species of atoms. The current density in a pulsed discharge can approach 300 A/cm 2 as a result 
of the extensive ionization that occurs. In the afterglow of a pulsed discharge, electrons rapidly ther- 
malize and recombination and dissociative-recombination processes, involving long-lifetime species of 
atomic and molecular ions and excited atoms, dominate. In both pure gases and mixtures of gases these 
processes lead to transient laser-oscillation with high gain and high-output power, but at low equivalent 
CW-power. 

Conditions in a pulsed discharge or in the afterglow are not readily specified by a simple pD- 
relationship. They are determined by the voltage at breakdown of the gas; the gas; gas pressure; the 

183 



184 



Handbook of Lasers 



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6 Neutral Gas Lasers 185 

energy dissipated in the discharge; the external-circuit resistance; and the shape of the leading-edge and 
trailing-edge of the current pulse. 

In the tables details of the type of pulsed excitation used are only given where this is considered 

important. 

Short Rise-Time Pulsed Discharges 

Short rise-time pulsed discharges are used almost exclusively for exciting self-terminating transient 
gas lasers. In these discharges the pulse rise-time must be comparable to the radiative life-time of the 
upper laser level to produce population inversion. 5 The current densities at the peak of the pulse are of 
the order of hundreds to thousands of Amps/cm 2 . Excitation conditions in the discharge are dependent 
on the energy dissipated per unit time; the gas pressure; the breakdown voltage of the gas; the anode- 
cathode geometry and the shape of the electrodes. Because of the finite breakdown time of a longitudinal 
column of gas, multi-electrode discharge-structures 8 ' 84 have a definite advantage over longitudinal two- 
electrode discharge-structures as a means of short rise-time pulsed excitation. 

In the tables limited details are given of the experimental conditions used to give transient oscillation, 
where this is considered relevant. 



DESCRIPTION OF THE TABLES 

Laser transitions are arranged according to groups in order of increasing atomic number. Where 
the laser transition has been identified, the calculated wavelength in air is given as reported in the liter- 
ature. Wavelengths of lines in vacuo are given in italics. 

In common with a well-established laser practice the upper state of a transition is given before the 
lower state. The first reference given to a particular line is that in which oscillation was first reported. 
The references included are not intended to be exhaustive and do not refer necessarily to work on laser 
systems. Those selected are intended to provide a source of information on the physical processes in 
neutral gas lasers that lead to selective excitation of the upper state involved in the laser oscillation. 

Unless otherwise stated, the energy levels are as given by Charlotte E. Moore in Atomic Energy 
Levels, volumes I, II and III, (1949, 1952, 1958) NBS Circular 467, U.S. Government Printing Office, 
Washington, D. C. 20402. 

Throughout, the following brief nomenclature is used 
A' — excited state of atom A; 
A* — metastable state of atom A ; 
A^ — difference in internal energies at infinite nuclear separation of free atoms. 



186 Handbook of Lasers 
TABLE 6. 



NEUTRAL LASER TRANSITIONS 



Wavelength 



Identification 



Notes 



Excitation 



6.1 A GROUP I A 



1.8751 First member of the 

Paschen Series, 
strongest fine- 
structure 
component 
4f 2 F$ /2 -3d 2 D 5/2 . 

1.1382* 4s 2 Si /2 - 3p 2 P 1/2 



1.1404* 4s 2 S 1/2 - 3p 2 P 3/2 

1.2434 5s 2 Si /2 -4p 2 P 1/2 

1.2523 5s 2 S 1/2 - 4p 2 P 3/2 

3.2040t 8p 2 P? /2 - 6d 2 D 3/2 

7.1821t 8p 2 n,i - 8s 2 Si /2 



6.1.1 HYDROGEN (Figure 6-2) 

As an impurity in 3.5 Torr of 
helium; optimum hydrogen 
pressure 0.01 Torr, D = 7 mm. 



Pulsed 



6.1.2 SODIUM (Figure 6-4) 

0.001-0.003 Torr vapor pressure 
of sodium with 1-10 Torr of 
hydrogen, helium or neon, 
hydrogen optimum at 5 Torr; 
D = 12 mm. 



Pulsed 



Pulsed 



6.1.3 POTASSIUM (Figure 6-3) 

0.1 Torr of potassium with 3-5 Torr Pulsed 
of hydrogen.** 

,, Pulsed 

6.1.4 CESIUM (Figure 6-5) 

Vapor pressure of cesium at a CW 

temperature of 175°C, D = 10 mm. 

CW 



6.1 B GROUP IB 



0.510554 



0.578213 



0.627818 



6.1.5 COPPER (Figure 6-6) 
4p 2 P 3/2 - 4s 2 2 D 5/2 Greater than 0.1 Torr vapor 



4p 2 P? /2 -4s 22 D 3/2 



Short rise-time 
pressure of copper with 1-3 Torr high voltage 

of helium, D = 10 mm. pulses. J 



6.1.6 GOLD 



6p 2 P? /2 — 6s 2 2 D 3/2 Vapor pressure of gold at a 

temperature of about 1500°C, 
D = 10 mm. 



Short rise-time 
high voltage 
pulses. 



6. 2 A GROUP II A 



References 



1,207 



2-4 

2-A 

4 
4 

11-13 
14, 11-13 



5-10 

5-7, 10 
9, 5, 10 



5.5457 



4p X P? - 3d *D 2 



6.2.1 CALCIUM 

Minimum vapor pressure of 
calcium at a temperature of 
460°C with 3 Torr of helium 
or neon in small-bore tubes. 



Short rise-time 
high voltage 
pulses. § 



15 



* Selective excitation of the upper laser level occurs via the charge neutralization reaction : Na + + H ~ -> Na'(4s 2 S i/2 ) + H. 
** Bore of the discharge tube apparently 12 mm. 

t Selective excitation of the upper laser level is by optical pumping through resonance absorption on the Cs 6s 2 S 1/2 
8p 2 P°/ 2 transition by the strong He-I line at 0.3889 ftm. 

+ The gain of these transient laser lines is greater than 42 dB/m. 

§ The single-pass gain on this transient laser line is greater than 300 dB/m. 



6 Neutral Gas Lasers 



187 



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Handbook of Lasers 



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6 Neutral Gas Lasers 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



189 



5r 



t 



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z 

UJ 



I/2- 

3/2 

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Fig. 6-6. Transient laser transitions in copper vapor at 0.5105 fim and 0.5782 fim. (Ref. 5) 



190 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 
(fxm) 


Identification 


Notes 


Excitation 


References 


6.4567 


5p X P? - 4d *D 2 


6.2.2 STRONTIUM 

Vapor pressure of strontium at a 
temperature greater than 


Short rise-time 
pulses.* 


15 



6p 3 P? - 6s % 
4f 3 F 4 , 3(2 -5d 3 D 3 



5.25 GROUP IIB 



0.8390** 

1.1869** 

1.4330 
1.6485 

0.3545f 
0.70651 

0.8677 

1.11768 

1.2222 

1.2246 

1.2545 

1.2760 

1.2981 

1.3655 
1.36755 

1.5295 



7p *P? - 7s % 



Possibly the following 
transition 
7p 3 P? - 7s 3 Si 



6p' 3 P° - 7s 3 S ± 



460°C with 3 Torr of helium or 
neon in small-bore discharge 
tubes. 



6.2.3 CADMIUM 

0.03-0.05 Torr of cadmium, Pulsed 

optimum 0.01 Torr with 2-20 

Torr of helium, D = 12 mm. 
0.03-0.05 Torr of cadmium with Pulsed 

0.05-1.0 Torr of helium or neon; 

D = 12 mm. 
0.03-0.05 Torr of cadmium with Pulsed 

2-20 Torr of helium; D = 12 mm. 

Pulsed 
6.2.4 MERCURY (Figure 6-7) 

In a mixture of mercury and argon. Pulsed 
A few mTorr of mercury and argon, Pulsed 

D — 5 mm. 
0.001 Torr of mercury with 0.8-1.2 Pulsed 

Torr of helium, D = 15 mm. 
0.09-0.12 Torr of mercury with Pulsed 

0.005-0.05 Torr of helium. 
0.001 Torr of mercury with argon Pulsed 

at 0.2 Torr, D = 5 mm. 
In a mixture of mercury and argon, Pulsed 

D = 5 mm. 
0.001 Torr of mercury with 0.8-1.2 Pulsed 

Torr of helium, D = 15 mm. 
0.001 Torr of mercury with 0.2 Pulsed 

Torr of argon, D = 5 mm. 
0.001 Torr of mercury with 0.8 Torr Pulsed 
of argon or 1.2 Torr of helium, 
X> = 15mm. 
0.001 Torr of mercury with 0.8-1.2 Pulsed 

Torr of helium, D = 15 mm. 
0.09-0.12 Torr of mercury with Pulsed 

0.005-0.05 Torr of helium, 
D = 6 mm. 
0.09-0. 1 2 Torr of mercury with CW 

0.1-1.0 Torr of helium, neon, 
krypton or argon; D = 6 mm. 



16 

16 

16 
16 

17 
17 

19 

19,20 

21, 12, 17 

21, 12, 17 

19 

21,17 

19 

19 
20 



22, 12, 19, 20, 
23-27 



* The single-pass gain on this line is typically 300 dB/m. 
** This line is possibly a Cd-II line. 

Mm, Jv^^tffil^wl^^'Sbff" 1 ' ^ WaVelen8th meaSUrement is —ate, this is possibly a line at 0.354506 
% This line is possibly an Ar-I line, since no mercury lines are reported close to this wavelength. 18 



6 Neutral Gas Lasers 191 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 

80,000 




60,000 



Fig. 6-7. Partial term-scheme of Hg-I, showing the majority of reported laser transitions. Circles represent odd-levels, 
horizontal lines even-levels. (From Ref. 20 by permission of the Optical Society of America.) 



192 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS {Continued) 



Wavelength 



Identification 



Notes 



Excitation 



6.2.4 MERCURY (Continued) 



References 



1.69202 


5f X F| - 


- 6d *D 2 


0.09-0.12 Torr of mercury with 
0.005-0.05 Torr of helium, 
D = 6 mm. 


Pulsed 


19, 12, 20 


1.69423 


5f 3 F§- 


- 6d 3 Di 




Pulsed 


19, 12, 20 


1.70733 


5f 3 F°. - 


- 6d 3 D 3 


>> 


Pulsed 


19, 12, 20 


1.71098 


5f 3 F£- 


- 6d 3 D 2 


,, 


Pulsed 


19, 12, 20 


1.73297 


7d x D 2 


- 7p *PJ 


0.09-0.3 Torr of mercury with 
0.005-0.1 Torr of helium, neon, 
krypton or air, D = 6 mm. 


Pulsed 


25,20 


1.81296 


6p' 3 F£ 


- 6d 3 D 3 


» 


CW 


22, 12, 19, 20 
23-26 


3.34* 


6p' 3 F 4 


- 8s 3 Si 


0.3 Torr of mercury with 0.25 Torr 
of krypton, D = 8 mm. 


Pulsed 


25,20 


3.930** 


6d 3 D 3 
or 5g G - 


- 6p' 3 P£ 
5fF° 


99 


Pulsed 


25,20 


5.880 


6p' 'P? 


- 7d 3 D 2 


99 


Pulsed 


27, 20, 24, 25 


6.490 


9s % - 
orllp 3 P° 


- 8p ^ 

- 10s 3 S X 


» 


Pulsed 


27, 20, 24 



6.3 GROUP III 



0.5350 



7s 2 S 1/2 - 6p 2 P° /2 



6.3.1 THALLIUM 

More than 0.01 Torr of thallium 
with several Torr of neon or 
helium, D = 1.3, 2.0 or 3 mm. 



Short rise-time 
pulses. 



* This line is possibly not a Hg-I line, but a Kr-I line. 20 
** The classification is as in Ref. 20. 



28, 195 



6.4 GROUP IV 








6.4.1 CARBON 






0.833515 


3p % - 


- 3s X P? 


In mixture of carbon dioxide and 
neon at 4 Torr, D = 15 mm. 


Pulsed 


29 


0.94057 


3p x D 2 


- 3s ^ 


As for 0.8335-jLtm line, carbon 
monoxide with helium at 2-16 
Torr. 


Pulsed 


29,30 


1.06831 


3p 3 D 2 


- 3s 3 P? 


As for 0.8335-/z.m line, also in 
0.05 Torr carbon monoxide with 
helium at 2-16 Torr. 


Pulsed 


29,30 


1.06853 


3p 3 Gi 


- 3s 3 P 


0.05 Torr carbon monoxide with 
2-16 Torr of helium. 


Pulsed 


30 


1.06912 


3p 3 D 3 


- 3s 3 P^ 


0.01 Torr of carbon dioxide or 
carbon monoxide with 2 Torr of 
helium, D = 5 mm. 


CW 


32, 12, 29, 30, 
33,34 


1.45425 


3p x Pi - 


- 3s J P? 


>> 


CW 


32, 12, 30, 33, 34 



6 Neutral Gas Lasers 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



193 



Wavelength 



Identification 



Notes 



Excitation 



References 



2.0645 


5d J D2 


-4p 3 P 2 


3.4046 


4d 1 D 2 ' 


-4?^ 


3.5155 


6d 3 P? - 


- 5p 3 D 3 


5.5956 


4p 3 S t - 


- 3d 3 P? 


1.198418 


4p 3 D 2 


- 4s 3 P? 


1.203148 


4p 3 D 3 


- 4s 3 P§ 


1.588402 


5s 3 P? - 


-4p 3 Di 



0.657903 lOd 3 D , 2 - 6p 3 Pi 



0.363954 6p7s 3 P? - 6p 2 3 P X 



0.405779 6p7s 3 P? - 6p 2 3 P 2 

0.40621 3 6p6d 3 D? - 6p 2 *D 2 

0.72290** 7s 3 P? - 6p 2 X D 2 



6.4.1 CARBON (Continued) 

0.02 Torr of carbon monoxide with 
1 Torr of helium, D = 10 mm. 



6.4.2 SILICON 

0.03 Torr of SiCU or 0.04 Torr with 
0.5 Torr of neon, D = 6 mm. 

0.03-0.05 Torr of SiCU with 1-5 
Torr of neon, D = 6 mm. 

6.4.3 TIN 

In SnCl 4 vapor at room tempera- 
ture, D = 5.6 mm. 

6.4.4 LEAD (Figure 6-8) 

Vapor pressure of Pb 208 at a 
temperature of 800-900°C, with 
helium, neon or argon, 
D = 2 mm.* 



0.2 — 2.0 Torr vapor pressure of 
lead,* 3 Torr of helium, 
D = 10 mm. 



CW 

CW 
CW 
CW 

CW 

CW 
CW 



Pulsed 



33 

33 
33 
33,12 

35 

35 
35 



36,37 



Fast rise-time 


38 


high voltage 




pulses transient 




oscillation. 




*» 


38 


,, 


38 


99 


39, 5, 38^10 



6.5 GROUP V 



0.4120t 









0.4321 






— 


0.4329 









0.4525f 






— 


0.4750t 









0.5440f 






— 


0.5500t 






— 


0.5540t 






— 


0.85940 


3p 


2po 

*l/2 


- 3s 2 P 1/2 


0.86284 


3p 


2po 
*3/2 


— 3s P3 /2 



6.5.1 NITROGEN 

In mercury-nitrogen mixture at 
0.001-0.02 Torr, D = 3 mm. 

In theta-pinch discharge in 1 Torr 
of nitrogen, D = 25 mm. 

In mercury-nitrogen mixture at 
0.001-0.02 Torr, D = 3 mm. 



In a mixture of nitrogen and helium 
at about 4 Torr, D = 15 mm. 

0.2-0.7 Torr of nitrogen with 3.0 
Torr of helium or 0.15 Torr of 
nitrogen, D = 15 mm. 



Pulsed 


41 


Pulsed 


42 


Pulsed 


42 


Pulsed 


41 


Pulsed 


41 


Pulsed 


41 


Pulsed 


41 


Pulsed 


41 


Pulsed 


29 



Pulsed 



43, 29, 30 



* The vapor pressure of lead can be deduced from " Vapor pressure data for the more common elements," R. E. Honig, 
R.C.A Review, 18, 195-204, June 1957. 

** A single-pass gain of 600 dB/m has been reported on this transient laser line. 40 

t There is some doubt about the accuracy of the determination of the wavelength of this line, and the assignment here 
to neutral species of nitrogen is perhaps dubious. 



194 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS {Continued) 



Wavelength 
(fxm) 



Identification 



Notes 



Excitation 



References 



0.91 876 3p' 2 D? /2 - 3s' 2 D 3/2 

0.93868 3p a D§ /2 - 3s 2 P 1/2 



0.93928 
1.34295 



1.3585 



1.45423 



1.4577 



3.7942 



3.8154 



3p 2 D? /2 - 3s 2 P 3/2 
3p 2 S? /2 - 3s 2 P 1/2 



3p 2 S? /2 - 3s 2 P 3/2 



4s 4 P 5/2 - 3p 2 D? /2 



6.5.1 NITROGEN {Continued) 

In a mixture of nitrogen and 
helium at 4 Torr, D — 15 mm. 

0.02-0.2 Torr of nitrogen or 
nitrous oxide with 0.01-0.1 
Torr of oxygen, hydrogen, helium 
or neon, D = 3 mm ; or in a 
mixture of nitrogen and helium 
at 4 Torr, D = 15 mm. 

0.15 Torr of nitrogen with 3.0 

Torr of helium; or 0.2-0.7 Torr 

of nitrogen, D = 15 mm 

(or 75 mm?). 
0.03 Torr of nitric or nitrous oxide 

with 2 Torr of helium or 1 Torr of 

neon, D = 5 mm. 
0.2-0.7 Torr of nitrogen, or 0.15 

Torr of nitrogen with 3 Torr of 

helium, D = 15 mm (or 75 mm?). 
0.03 Torr of nitric or nitrous oxide 

with 2 Torr of helium or 1 Torr 

of neon, D = 5 mm. 
0.2-0.7 Torr of nitrogen or 0.15 

Torr of nitrogen with 3 Torr of 

helium, D = 15 mm (or 75 mm?). 
0.15 Torr of nitrogen, 3.0 Torr of 

helium or 0.2-0.7 Torr of 

nitrogen, D = 15 mm (or 75 mm?). 



Pulsed 
CW 



29 

43, 29, 30, 44, 45 



CW 

Pulsed 



CW 



Pulsed 



CW 



Pulsed 



Pulsed 



43, 29, 30, 44, 45 
43 



43, 12, 30, 33, 34 



43 



33,34 



43 



43 



6.6 GROUP VI 



0.4525" 

0.844628^1 
0.844638 1 
0.844672 I 
0.84468oJ 



3p 3 Po. 2 ,i-3s 3 S? 



0.882045 3P 1 ^3 - 3s 1 l J}% 

2.890 4p 3 P - 4s 3 S° 



6.6.1 OXYGEN 

As an impurity in mercury-nitrogen 
mixture. 

Approximately 0.01-0.04 Torr of 
oxygen with 0.35 Torr of neon, 
1.4 Torr of argon, carbon mon- 
oxide or dioxide or helium, 
D = 1 mm. As an impurity in 
bromine with helium or neon, 
also in nitrous oxide; and in 
pure oxygen at 0.1-2 Torr, 
2> = 10mm. so 

In carbon dioxide and neon at 4 
Torr, D = 15 mm. 

0.08 Torr of oxygen with 0.5-1.0 
Torr of helium or neon (probably 
D = 5 or 7 mm). 



Pulsed 


41 


CW 


46, 12, 29, 31, 




34, 43, 48-54 



4.563 



4p 3 P - 3d 3 D C 



Pulsed 
CW 

CW 



29 
55 

55 



* This line is possibly a nitrogen line, though there is doubt about the accuracy of the reported wavelength. 

** This is the O-I triplet, as shown in Ref. 48. The quartet oscillation is due to the large Doppler width of the line (caused 
by excitation and dissociation of oxygen molecules) and radiation trapping at the line center, causing gain to occur only in the 
wings of the line (see Fig. 6-26). 



6 Neutral Gas Lasers 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



195 



Wavelength 


Identification 


5.981 


7d 3 D° - 6p 3 P 


6.8161 


3s' 3 D2-4p 3 P a .i.o 


6.858 


5p 3 P - 5s 3 S° 


6.8731 


3s' 3 D§-4p 3 P 2 


10.400 


5p 3 P - 4d 3 D° 



Notes 



Excitation 



0.516032* 

0.521962* 
1.0455 



1.0636 
0.5454* 

0.5640* 
0.6350 



4p 3 P 2 - 4s 3 S? 



4p /1 F 3 -4s /1 DS 



6.6.1 OXYGEN (Continued) 

0.08 Torr of oxygen with 0.5-1.0 

Torr of helium or neon (probably 

D = 5 or 7 mm). 
In pure oxygen, D = 15 mm (or 

75 mm?). 
0.08 Torr of oxygen with 0.5-1.0 

Torr of helium or neon (probably 

D = 5 or 7 mm). 
In pure oxygen, D = 15 mm (or 

75 mm?). 
0.08 Torr of oxygen with 0.5-1.0 

Torr of helium or neon (probably 

D = 5 or 7 mm.). 

6.6.2 SULFUR 
In sulfur dioxide or hexafluoride at 

0.015-0.06 Torr, D = 1.5-6 mm. 

In 0.03 Torr of SF 6 or 0.03 Torr of 
SF 6 with 2 Torr of helium. Also 
with H 2 S, with helium, neon or 
argon, D = 5 mm. 

6.6.3 TELLURIUM 

Tellurium at a temperature of 
125-250°C with 0.1-0.25 Torr of 
neon, D = 6 mm. 

0.001-0.002 Torr of tellurium, 
0.2 Torr of neon, D = 3 mm. 



CW 

Pulsed 
CW 

Pulsed 
CW 

Pulsed 

Pulsed 
CW 

CW 

Pulsed 

Pulsed 
Pulsed 



6.7 A GROUP VIIA 



0.7024 



0.7039 
0.7129 

0.945206 



1.3863** 
1.3893** 



3p 2 P§ /2 - 3s 2 P 



1/2 



6.7.1 ATOMIC FLUORINE (Figure 6-9) 
Under flowing conditions with CF 4 , 
SF 6 or C 2 F 6 at 0.03-0.1 Torr 
with helium at 2-10 Torr, 
D = 25 mm. 



3p 2 P2/ 2 - 3s 2 P 3/2 
3p 2 P°/2 - 3s 2 P 1/2 

4p 2 P3/2-4s 2 P 1/2 



3d 2 D 3/2 - 4p 4 D? /2 
3d 4 P 3/2 - 4p 4 D§ /2 



6.7.2 ATOMIC CHLORINE (Figure 6-10) 
In chlorine at 0.010-0.080 Torr 
with 0.3-3 Torr of helium or 
neon, D = 6 mm. Also in Freon 
at 0.001 Torr with 0.8 Torr of neon, 
D = 7 mm. 
In 0.3 Torr of HC1 with 0.1 Torr of 
helium or neon, D = 14 mm. 



Pulsed 



Pulsed 
Pulsed 

CW 



Pulsed 
Pulsed 



References 



55 

43 
55 

43 
55 

56 

56 

34, 33, 57 

34, 33, 57 
58 

58 
59 



194 



194 
194 

60-62 



62 
62 



* Possibly an ion line. . 

** Classification of these lines is as in C. J. Humphrey and E. Paul, Jr., "First spectrum of chlorine; an extension based on 
observations in the 7000 to 25,000 A region," /. Opt. Soc. Am., 49, 1180-1187, 1959. 



196 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



p o P. P 2 



6p7p 



6p6d 




Fig. 6-8. Transient laser transitions in lead vapor. 



118,937 



0.7039/1 
0.7204/1 



104,731 



4 t 



2 P. 



-£, 



3p 



0.7129/i. 



2P, 



3s 



0-L 



2 P. 



GROUND STATE 3/2 

Fig. 6-9. Energy diagram for laser transitions in atomic fluorine. (Ref. 194) 



6 Neutral Gas Lasers 197 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



4S 
2p 4 p 



90 



io 



b 85 



2 
o 

g 80 

UJ 

z 

UJ 



75 



70- 



L 



«P 



2 S° 4 S° 2 P° 4 P° 2 D° 4 D° 



3d 
2p 4 p 2 D 4 D 2p 





7/2 



1/2 



2.0199^ 
.9755ft 
2.4470/i. 



3/2 



Fig. 6-10. Laser transitions in atomic chlorine. (Ref. 62) 



198 



Handbook of Lasers 



TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 
(fi.m) 



Identification 



Notes 



Excitation 



1.58697* 
1.9755 

2.0199* 
2.4470* 

3.0672 



0.980 § 



6.7.2 ATOMIC CHLORINE (Continued) 
3d 4 F 9/2 - 4p 4 D 7/2 In a mixture of freon (CCI 2 F 2 ) CW 

and helium at 3.3 Torr 
In HO, or 0.3 Torr of silicon CW 

tetrachloride with 0.1 Torr of 
helium or neon, or 0.1 Torr of 
chlorine, D = 6 mm. 



3d 4 D 7/2 -4p 4 P£ /2 



3d 4 D 5/2 - 4p 4 P 3/2 
3d 4 D 7/2 -4p 4 D? /2 



5p 2 T>%, 2 - 5s 2 P 3/2 



In 0.3 Torr of HC1 with 0.1 Torr 
of helium or neon, D = 14 mm 
(pulsed) or in 0.09 Torr of 
chlorine with 1.5-7.2 Torr of 
helium, D = 25 mm. 

In 0.09 Torr of chlorine with 2.1 
Torr of argon, D = 25 mm.** 
6.7.3 BROMINE (Figure 6-11) 



CW 



CW 



CW 



1.010§ 


— 


1.030§ 


— 


1.060§ 


— 


1.3152 


5p 5 2 P? /2 - 5p 5 2 P 3/2 


1.4542|| 


7p[l]§/2-6d[2] 3/ 2 


2.5987|| 


5d[2] 3/2 -6p[l£ /2 


2.7572 


( 1 D 2 )5d[2] 5/2 




-( 1 D 2 )6p[l]§ /2 


3.036 11 


5d[2] 3/ 2-6p[l]§ /2 


3.236 


( 3 P 2 )5d[2] 5/2 - 




( 3 P 2 )6p[l]^ /2 


3.4291f 


( 3 P 2 )5d[4] 7/2 - 




( 3 P 2 )6p[3] 5 ° /2 



6.7.4 IODINE 

0.1 Torr vapor pressure of iodine 
with a few Torr of helium, 
D = 5 mm. 



Tens of Torr of CF 3 I or CH 3 I, 

D — l mm. 
In hydrogen iodide at 0.3 Torr, 

D = 14 mm. 
0.3 Torr of hydrogen iodide with 

0.3 Torr of neon, D = 14 mm. 
In hydrogen iodide, D = 12 mm. 



In CH 3 I and iodine vapor or CF 3 I, 

with helium, argon or xenon, 

D = 50 mm. 
In the hydrogen iodide or iodine CW 

vapor, D = 12mm. 
In CH 3 I, iodine vapor or CF 3 I and CW 

I 2 , Z> = 12 mm. 



Pulsed 



Pulsed 
Pulsed 
Pulsed 
Pulsed (flash 
photolysis) 
Pulsed 

CW 

CW 

CW 



References 



65,204 

63, 12, 35, 62, 
64, 65, 205 

64, 65, 205 
63, 12, 35, 62, 

64,65 
62, 205 



205 



0.8446f 


See Table 6.6.1 


— 







2.2866J 


4d[3] 7/2 - 5p[2]£ /2 


0.3 Torr of hydrogen bromide, 
D = 12 mm. 


CW 


68 


2.3513J 


4d[3] 5/2 - 5p[2]§ /2 


>? 


CW 


68 


2.8377J 


4d[3] 7/2 - 5p[3]? /2 


,, 


CW 


68 



69 

69 
69 
69 
70-73 

62 

62 

68 

74 

22, 64, 68 
22, 64, 68, 74 



* Classification of these lines is as in C. J. Humphrey and E. Paul, Jr., "First spectrum of chlorine; an extension based on 
observations in the 7000 to 25,000 A region," /. Opt. Soc. Am., 49, 1 180-1 187, 1959. 

** The upper laser level appears to be selectively excited in excitation transfer from the upper 4s-state of Areon I 2 ° 5 
Note: Lines at 1.589 2.499 2.535, 2.602, 2.784, 3.801 and 10.604 m , observed CW in discharges in He-CC1 2 F 2 and He-CBrF, 
mixtures, are possibly also Cl-I lines. 65 v r3 

t Laser lines close to this wavelength originally thought to be Br-I lines have been shown to be O-I lines 48 
» ll dGn lfy^ £? e xT ° n ^rm-yalues given by J. L. Tech, "Analysis of the spectrum of neutral bromine,'*' J. Res. Nat'l 
Bur S t ds., A67 505-554, Nov.-Dec. 1963; L. Mmnhagen, Arkiv Fysik, 21, 415, 1962; and C. C. Kiess and C. H Corliss, /. Res 
Nat 1. Bur. Stds., A63, 1, 1959. ~wiioa, j. hw. 

Note: The classification of these iodine laser lines, except where otherwise stated, are from C. C. Kiess and C H Corliss 
Description and analysis of the first spectrum of iodine," /. Res. Natl Bur. Stds, 63 A, 1-18, July-August 1959 ' ' 
§ This line is possibly a singly-ionized iodine line. 
|| Identification from L. Minnhagen, Arkiv Fysik, 21, 415, 1962. 
II Identification as in Ref. 64. 



6 Neutral Gas Lasers 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



199 



I0 3 X 80 



2 



>- 
e> 

UJ 

z 

UJ 



75 



70 



65 - 



( 3 p 2 )5s 



( 3 P 2 )5p 



4 P° 



V 



4p° 



( 3 p 2 )4d 



7^"/W 3 ' 2 



" // 



y 



\ 



i_X 



_ — ^ 



H 2 ] 5/2 



<> 



o 1 - 



\v 



\ 



\ 






X 



X 



8377^ 




[3] 5/2 
t3j 7/2 



X^-v„ 



J\ 



K 3/2 



Fig. 6-11. Laser transitions in atomic bromine (solid lines). The broken lines 
indicate transitions of strong spectral lines. (Ref. 68) 



200 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS {Continued) 



Wavelength 



Identification 



Excitation 



Notes 



References 



4.858 



4.862 

5.497 

6.720 

6.902** 

9.016** 



5d[l] 3/ 2-6p[2] 5/ 2 



5d[4] 9/2 - 6p[3] 7/2 
5d[2] 5/2 -6p[l] 3/ 2 
6s[2] 3/2 -6p[l] 3/2 
5d[3] 7/2 -6p[2] 5/2 
5d[3] 7/2 -6p[2] 5/2 



6.7.4 IODINE {Continued) 

In CH 3 I, CF 3 I or iodine vapor with 
helium, argon or xenon, 
D = 50 mm. 



CW 



74 



CW 


74 


CW 


74 


CW 


74 


CW 


74 


CW 


74 



6.7B GROUP VIIB 



0.5341065f y 6 P? /2 - a 6 D 7/2 



0.5420368 

0.5470640 

0.5481345 

0.5516777 

0.5537149 

1.28997 

1.32938 

1.33179 

1.36257 

1.38638 



1.39975 



y 6 P 5 °/2 

y 6 P§/ 2 

y 6 P 3 °/2- 

y 6 P3/ 2 

y 6 P 3 °/2 

Z P 7 / 2 ' 

T 6 P° 

z r 7/2 
a 6 P? /2 
z 6 P? /2 

Z 6 P 3 /2 



a 6 D 7/2 
a 6 D 5/2 
a 6 D 5/2 

• a D 3 /2 
a 6 D 1/2 

■ a D9/2 
a 6 D 7/2 

- a D-7/2 
a 6 D 1/2 
a 6 D 3/2 



6.7.5 MANGANESE (Figure 6-12) 

0.1-2.0 Torr of manganese (at a 
temperature of 1 100-1 300°C), 
with 1.0-2.0 Torr of helium or 
neon, D = 10 mm.* 



0.1-2.0 Torr of manganese (at a 
temperature of 1100-1300°C), 
with 1.0-2.0 Torr of helium or 
neon, D = 10 mm.* 



Short rise-time, 
high voltage 
pulses 



Short rise-time 
pulses 



z 6 P§ /2 - a 6 D 1/2 



66, 5, 67 



66, 5, 67 
66,67 
67,5 
66, 5, 67 
66, 5, 67 
66, 5, 67 
66, 5, 67 
66, 5, 67 
66, 5, 67 
66,5 



66,5 



6.8 GROUP NOBLE GASES 



1.8685 


4f 3 F-3d 3 D 


1.9543 


4p 3 P - 3d 3 D 


2.0581 3J 


2 'Ft - 2 % 


2.0603 


7d 3 D - 4p 3 P 


95.8 


3p i-Pt - 3d 1 D 1 


216.3 


4p 1 P-4d 1 D 



6.8.1 HELIUM (Figure 6-13) 
0.4 Torr of helium, D = 6 mm. 

2.7 Torr of helium, D = 1.3 mm. 



8.0 Torr of helium, with trace of 
argon or nitrogen, § D = 7 mm. 

0.5 Torr of helium, D = 75 mm 
(pulsed); 0.1 Torr of helium, 
D = 60 mm (CW). 

0.1 Torr of helium, D = 60 mm. 



CW 




75, 192 


CW 




76, 75, 77, 192 


Short rise-time 


28 


high voltage 




pulses. 






CW 




78, 12, 79 


CW 




80,81 



CW 



81 



* Identification is based on measurements of lines in spontaneous emission in Mn I, (M. A. Catalan, W. F. Meggers and 
O. Garcia-Riquelme, "The first spectrum of manganese, Mn I," /. Res. Nat' I Bur. Stds., 68 A, 9-56 (Jan.-Feb. 1964). 

** Reported at a presentation of paper 20T-5 at the Quantum Electronics Conference, Miami, May 1968. 

t Oscillation has been observed on six hyperfine components of this line. 67 

% This line is a transient laser line. 

§ The trace of argon or nitrogen is to depopulate the metastable He 2 3 S t level from which the 4p 3 P lower laser level is 
excited by electron impact. 



6 Neutral Gas Lasers 



201 



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202 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 



Identification 
Racah Paschen 



Notes 



References 



0.540056 



3p'[l/2] - 3s[3/2]? 



0.58525 



0.59393 



3p'[l/2] - 3s'[l/2]? 



5s'[l/2]? - 3p[5/2] 2 



0.594483 



0.60461 



0.61180 



0.614309 



0.62937 



0.63282 



3p'[3/2] 2 - 3s[3/2] 2 



5s'[l/2]? - 3p[3/2]x 



5s'[l/2]?-3p[3/2] 2 



3p[3/2] 2 - 3s[3/2]§ 



6.8.2 NEON (Figure 6-14) 



2pi — ls 4 



2pi - ls 2 



3s 2 - 2p 8 



2p 4 — ls 5 



3s 2 — 2p 7 



3s 2 — 2p 6 



2p 6 - lss 



5s'[l/2]? - 3p'[3/2]! 3s 2 -2p 5 
5s'[l/2]? - 3p'[3/2] 2 3s 2 - 2p 4 



Transient line requiring short rise-time 
high voltage, high current pulses. In 
3 Torr of neon, D = 5 mm in a 
longitudinal discharge system. In a 
transverse discharge system, 84 
30-35 Torr of neon with interelectrode 
separations of 2.5-10 cm. 

Transient line observed in a pulsed 
He-Ne mixture requiring trace of 
argon to destroy Ne-ls metastables. 
Total pressures 1-200 mTorr, 
D = 3 mm. 

CW. In a 5 : 1 He-Ne mixture at 3.6 
Torr-mm. Need to suppress 
superradiant 3.39-/zm (3s 2 — 3p 4 ) 
line and strong 0.6328-jum (3s 2 — 2p 4 ) 
line. The Ne 3s 2 level is selectively 
excited mainly by He 2 1 S metastables in 
an endothermic excitation transfer 
reaction. 

Transient line requiring short rise-time, 1 
high voltage, high current pulses. 
In about 0.3 Torr of neon, D = 5 mm 
and pulse current of 120 A. 

CW. In a 5 : 1 He-Ne mixture at 3.6 
Torr-mm. Need to suppress 
superradiant 3.39-/xm line and the 
strong 0.6328-jU.m line. 

CW. In a 5 : 1 He-Ne mixture at 3.6 
Torr-mm. Need to suppress 
super-radiant 3.39-£im line and the 
strong 0.6328-/xm line. 

Transient line requiring short rise-time, 
high voltage, high current pulses. In 
about 0.3 Torr of neon, D = 5 mm 
and pulse current of 120 A. 

CW. In a 5 : 1 He-Ne mixture at 3.6 
Torr-mm. Need to suppress 3.39-ftm 
and 0.6328-jU.m lines. 

CW. Strongest of the 3s 2 — 2p lines. 
In a 5 : 1 He-Ne mixture at 
3.6 Torr-mm. The He-Ne mixture 
ratio and pressure depend on the 
bore of the discharge tube. 102 The 
Ne-3s 2 level is selectively excited 
mainly by He 2 1 S metastables 
in an endothermic excitation transfer 
reaction, as well by direct electron 
impact. 94,97 



82, 5, 83, 84 



85, 12 



86, 12, 87* 



I, 82, 89, 90 



86, 12 



91,12,86,87* 



I, 82, 89, 90 



91,86 



92, 12, 86, 
91-115. 



* Although oscillation between the Ne-3s 2 and 2p levels is normally observed only in a He-Ne mixture, it has been 
reported to have been observed on the 0.59393 and 0.61180-ju.m lines under pulsed conditions in pure neon. 87 In view of the 
excitation used and non-observation of oscillation on the 0.6328-m line, it is likely that the two lines mentioned above should 
have been identified as 0.5944-/Ltm and 0.6143-/Lim transient laser lines. 



6 Neutral Gas Lasers 203 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



10° X 170,- 



4f-4d 




Fig. 6-14. Energy-level diagram of neon, showing laser transition groups. 



204 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 
(fxm) 



Identification 



Racah 



Paschen 



Notes 



References 



0.63518 



0.64011 



0.73048 

0.88653 
0.89886 
0.9486 

0.9665 

1.0295 
1.0621 



5s'[l/2]? - 3p[l/2] 

5s'[l/2]? - 3p'[l/2]i 3s 2 -2p 



5s'[l/2]? - 3p[l/2] 

4s'[l/2]? - 3p[l/2]! 
4s'[l/2]g - 3PE1/2]! 
4s[3/2]? - 3p[l/2], 

4s[3/2]S-3p[l/2] 1 

4s'[l/2]? - 3p[5/2] 2 
4s'[l/2]J - 3p[3/2h 



6.8.2 NEON {Continued) 
3s 2 — 2p 3 



3s 2 — 2pi 

2s 2 - 2pi 
2s 3 — 2pi 
2s 4 — 2pio 

2s 5 — 2p 10 

2s 2 - 2p 8 
2s 2 — 2p 7 



1.0798 


4s'[l/2]§ - 3PP/2]! 


2s 3 - 2p 


1.0844 


4s'[l/2]? - 3p[3/2] 2 


2s 2 — 2p, 


1.1143 


4s[3/2]? - 3p[5/2] 2 


2s 4 — 2p { 



1 . 1 1 77 4s[3/2]5 - 3p[5/2] 3 2s 5 - 2p 9 



1.1390 4s[3/2]§ - 3p[5/2] 2 2s 5 - 2p 8 

1.1409 4s'[l/2]? - 3p'[3/2]! 2s 2 - 2p 5 

1 . 1 5228 4s'[l /2]? - 3p'[3/2] 2 2s 2 - 2p 4 



CW. As for the 0.6328-/Ltm line; need to 
suppress the 3.39-/xm and the 
0.6328-yu,m lines. 

CW. As for the 0.6328-jiim line; need 
to suppress the 0.6328-jnm line by 
the use of a prism or an unstable 
optical cavity and a discharge current 
more than optimal for the 0.6328-^cm 
line. 

CW. As for 0.6328-^m line; need to 
suppress the 3.39-/im and 0.6328-jU,m 
lines. 

CW. Observed in a very long discharge 
tube. 

CW. Observed in a very long discharge 
tube. 

Pulsed. Observed in a hollow cathode 
discharge in a Ne-H 2 mixture; need to 
suppress oscillation on other 2s — 2p 
transitions. 

Pulsed. Observed in a hollow cathode 
discharge in a Ne-H 2 mixture; need to 
suppress oscillation on other 2s — 2p 
transitions. 

CW. Observed in a very long discharge 
tube. 

CW. In a He-Ne mixture, 0.15-Torr 
partial pressure of neon and 2.8-Torr 
total pressure, D probably 5-10 mm. 
The gain on this transition is only a 
few tenths of a percent per meter even 
with oscillation suppressed on 
competing transitions. 

CW. In a 10 : 1 He-Ne mixture at a 
pZ> of 7-14 Torr-mm. 

CW. As for 1.0798-^m line. 

CW. As for 1.0798-^m line. Also 
observed in hollow cathode discharge 
in pure neon and in a mixture of neon 
and hydrogen; hydrogen destroys the 
Ne-ls metastables. 

CW. As for 1.1143-^m line. 



86 



91,86, 113,114, 
186, 193 



86 

115,116,200 
115, 116 
117,118 

117,118,200 

115,116,200 

119, 12, 115, 
116, 120, 121 



122,47,99,116 

122,47,99,116, 

121 
122, 47, 99, 

116-118, 

123-127 



CW. As for the 1.0798-^m line. 

CW. As for the 1.1143-|u,m line. 
CW. Strongest of the 2s — 2p lines. 
In a 10 : 1 He-Ne mixture at about 



128, 12, 93, 

116-118, 120, 

123, 125, 127, 

200 
122, 47, 93, 

116-118 
93,47, 116-118 
128, 12, 47, 93, 

97, 99, 



6 Neutral Gas Lasers 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



205 



Wavelength 
(jLim) 



1.15250 



1.1602 
1.1614 
1.1767 

1.1789 

1.1985 
1.2066 

1.2460 

1.2586 



Identification 



Racah 



Paschen 



Notes 



References 



4s[3/2]? - 3p[3/2h 



4s'[l/2]? - 3p[l/2] 
4s[l/2]g - 3p'[3/2]i 
4s'[l/2]? - 3p'[l/2]j 

4s[3/2]? - 3p[3/2] 2 

4s'[l/2]8 - 3p'[l/2]! 
4s[3/2]8 - 3p[3/2] 2 

4s[3/2]? - 3p'[3/2]! 



1.2594 


4s[3/2]? - 


- 3p'[3/2] 2 


1.2689 


4s[3/2]? - 


- 3p[l/2] 


1.2767 


4s[3/2]S - 


- 3p'[3/2]! 


1.2887 


4s[3/2]? - 


- 3p'[l/2]? 


1.2912 


4s[3/2]§ - 


- 3p'[3/2] 2 


1.3912 


4s[3/2]^ - 


- 3P11/2]! 


1.4276 




— 


1.4304 




— 


1.4321 




— 


1.4330 




— 



6.8.2 NEON (Continued) 



2s 4 - 2p 7 



2s 2 - 2p 3 
2s 3 - 2p 5 
2s 2 - 2p 2 

2s 4 — 2p 6 

2s 3 - 2p 2 
2s 5 - 2p 6 

2s 4 - 2p 5 



5f[9/2] 4>s -3d[7/2]S 5V-3d 4 

2s 4 — 2p 4 
2s 4 - 2p 3 



2s 5 — 2p 5 
2s 4 - 2p 2 

2s 5 - 2p 4 
2s 5 — 2p 2 



11 Torr-mm. The Ne-2s levels are 123-134, 191, 

selectively excited mainly by He 2 3 Si 200 

metastables in an exothermic excitation 

transfer reaction as well as by direct 

electron impact. 97,99 Observed also in 

hollow cathode discharges in pure 

neon, and mixtures of neon and 

hydrogen, and neon and oxygen. 
CW. In a glow discharge in pure neon, 

optimum p£> is less than 0.5 

Torr-mm, helium suppresses 

oscillation. Observed also in hollow 

cathode discharges in pure neon and a 

neon-hydrogen mixture. 
CW. In a He-Ne mixture. 

CW. In a He-Ne mixture. 

CW. As for the 1.0798-ju.m line. Observed 

also in hollow cathode discharges in 

pure neon, and in mixtures of neon 

and hydrogen, and neon and oxygen. 
CW. Observed in a very long discharge 

tube, also in a hollow cathode 

discharge in a mixture of neon and 

hydrogen. 
CW. In a He-Ne mixture. 

CW. In a He-Ne mixture in glow and 
hollow cathode discharges. 

CW. Observed in a very long laser, 

also in a hollow cathode discharge in a 

mixture of neon and hydrogen. 
Pulsed, via optical pumping by a helium 136 

lamp; 0.2 Torr of neon, 3-4 Torr of 

helium, D = 5.2 mm. 
Pulsed. In a hollow cathode discharge in 1 17, 1 18 

a mixture of neon and hydrogen. 
CW. As for the 1.2460-/xm line. 



130, 12 


,77, 


116, 


117, 


123, 


125, 


127, 


128, 


130, 


134 






93, 47, 


116, 


120, 


128 






128, 6, 


47, 


93, 


116, 


124, 


133 


122, 93 


, 116-118, 


123- 


126, 


185, 


200 






115-118,127, 


200 






128, 4" 


', 93 


116, 


124 






128,47, 116-118, 


120, 


123 


124, 


133, 


185 




115-118 





CW. 

CW. Observed in a very long discharge 

in a He-Ne mixture. 
CW. As for the 1.2460-/xm line. 
Pulsed. In a hollow cathode discharge 

in a mixture of neon and hydrogen. 
CW. 
CW. 
CW. 
CW. 



76,80,116,117, 
125, 129, 135 

116, 117 
115 

115,80, 116, 117 

117, 118 

137 
137 
137 
137 



206 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 
{jxiri) 



Identification 
Racah Paschen 



Notes 



References 



1.4346 — 

1.4368 — 

1.5231 4s'[l/2]?-3p'[l/2] 

1.6405 6s[3/2K-4p[5/2] 3 



1.7161 4s[3/2]?-3p'[l/2] 

1.8210 4p'[l/2] 1 -4s[3/2]? 

1.8253* 4f[5/2] 2 . 3 - 3d[7/2]§ 

1.8281 4f[9/2] 4 , 5 - 3d[7/2]£ 

1.8287 4f[9/2] 4 - 3d[7/2] 3 J 

1.8309 4f[5/2] 3 , 3 - 3d[3/2]° 

1.8408 4f[5/2] 2 - 3d[3/2]? 

1.8596 4f[7/2] 3 - 3d[5/2]2 

1.8602 4f[7/2] 3 .4-3d[5/2]§ 

1.9574 4p'[3/2] 2 - 4s'[3/2]2 



1.9577 4p'[l/2] 1 -4s[3/2]S 

2.0350 4p'[3/2] 2 - 4s[3/2]? 

2.0356 4p'[l/2] 1 -4s[3/2]? 

2.1019 4d'[5/2]2 - 4p[3/2] 2 

2.1041 4p'[l/2]8-4s'[l/2]? 

2.1708 4p[l/2] -4s[3/2]? 

2.326 4p[5/2] 2 - 4s[3/2]§ 

2.37 Identified as the 

following 2.3951-^tm 
line. 147 

2.3951 4p'[3/2] 2 -4s[l/2]? 



2s 2 


-2p 


4s 5 - 


-3p 


2s 4 - 


-2p 


3pi 


-2s 


4Y 2 


3 


4f- 


3d 4 



3d 4 



4V - 3d 4 



4Y 
4Y 

4Z- 
4Z- 
3p 4 



3p 2 — 2s 5 



3p 4 — 2s 4 



6.8.2 NEON (Continued) 

— CW. 

— CW. 

CW. As for the 1.0798-^m line. 



Pulsed. Via optical pumping by a helium 

lamp; 0.2 Torr of neon, 3-4 Torr of 

helium, D = 5.2 mm. 
CW. As for the 1.2887-^m line. 
CW. As for the 1.2887-jiim line. 
CW. 
CW. In a 10 : 1 or 100 : 1 He-Ne 

mixture at a pD of about 8 Torr-mm. 
CW. In a 10 : 1 He-Ne mixture at a pD 

of about 8 Torr-mm. 
CW. As for the 1.8287-/*m line. 
CW. In a 100 : 1 He-Ne mixture at a pD 

of about 8 Torr-mm. 
CW. As for the 1.8281-/xm line. 
CW. As for the 1.8281-^m line. 
CW. In a He-Ne mixture. Oscillation is 

due to cascading from the super-radiant 

3.39-yum (3s 2 — 3p 4 ) line. Also in pure 

neon in a 10-m long discharge tube at 

0.01-0.05 Torr, D = 10 mm. 
CW. In a He-Ne mixture. Oscillation 

is due to cascade transitions from the 

well populated Ne-3s levels. 
CW. As for the 1.9574-/im line; also in 

pure neon at 0.01-0.05 Torr, 

D = 10 mm. 



3d 3 
-3d 2 

-3d'/ 
- 3d; 

-2s 5 



137 
137 
122,47,93, 116, 

138, 185 
136 



115, 116 

116 

12 

139, 136, 140, 

141 
139, 136, 140, 

141 
139, 136, 141. 
139, 136, 141, 

185 
139, 136, 141 
139, 138, 141. 
135,12,116,129, 

142 



116, 12, 80, 143 



3p. 

4s"" 
3p 



— 2s 4 



CW. As for the 1.9577-^m line. 



— 3p 6 (?) CW. Observed in a very long discharge 
tube. 
- 2s 2 CW. As for the 1 .9577-/xm line, but 

also oscillates in 250 mTorr of pure 
neon in an 8-m long, 10-mm bore 
discharge tube. 144 
3p 3 — 2s 4 CW. In pure neon at 0.05 Torr. Helium 

suppresses oscillation by selectively 
populating the 2s 4 lower laser level. 
3p 8 — 2s s CW. Observed in a very long discharge 

in pure neon or a He-Ne mixture. 
CW. 



3p 4 — 2s 2 CW. In a He-Ne mixture also in pure 

neon. Oscillation due to cascading 
through the superradiant 3s 2 — 3p 4 
transition at 3.39 /xm. 



144, 12, 76, 80, 
116, 125, 129, 
142, 143, 145, 
185 

116, 12, 125, 
129, 145 

81, 12, 116 

135, 12,80, 116, 
125, 129, 144 



80, 12, 116, 125, 
135 

116 

138, 147 



138, 80, 116, 
129, 142, 
146-149 



This line appears in Ref. 12, but no mention of it appears to have been made. 



6 Neutral Gas Lasers 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



207 



Wavelength 




Identifii 
Racah 


2.3956 


4p'[l/2] 1 


-4s[l/2]? 


2.42 


5s'[l/2]? 


-4p[l/2]i 


2.4226 


4d[3/2]? 


-4p[5/2] 2 


2.4250 


4p'[3/2], 


-4s'[l/2]? 


2.5400 


4d[l/2]? 


- 4p[3/2] 2 



Paschen 



Notes 



References 



2.5524 



2.7582 



2.7826 

2.864 

2.9456 

2.9676 

2.9813 

3.0268 

3.0726 



3.3182 



3.3342 
3.3362 
3.3813 
3.3840 
3.3903 



3.3913 



3.4481 



3.5845 
3.7746 
3.9817 



6.8.2 NEON {Continued) 



4p[l/2] 1 -4s[3/2] 2 ° 



4d[3/2]?-4p[l/2] 



5s'[l/2]§-4p[3/2] 1 

4d'[3/2]?-4p'[3/2] 2 

5s[3/2]?-4p[l/2] 1 

4d[3/2]?-4p'[3/2] 1 

4d[3/2]5-4p'[3/2]! 

4d[3/2]S-4p'[l/2] 1 

5s'[l/2]?-4p[l/2] 



5s[3/2]?-4p[5/2] 2 



5s'[l/2]?-4p'[3/2] 1 
5s[3/2]S-4p[5/2] 3 
7s'[l/2]g - 5p'[3/2]! 
7s'[\l2]°o-5p'[\l2h 
5s'[l/2]?-4p'[l/2]i 



5s[3/2]?-4p[3/2] 1 



5s[3/2]5-4p[3/2] 2 

4p'[l/2]o-3d[3/2]J 

5s[3/2]?-4p[l/2] 



3p 2 — 2s 2 
3s 2 — 3pi 

4d 2 — 3p 8 
3p 5 — 2s 2 
4d 5 - 3p 6 

3pi — 2s 5 

4d 2 - 3p 3 



3s 3 — 3p 7 
4s{ - 3p 4 
3s4 — 3pio 
4d 2 - 3p 5 
4d 3 - 3p 5 
4d 3 — 3p 2 
3s 2 — 3p 3 



3s 4 — 3p 8 



3s 2 — 3p 5 
3s 5 — 3p 9 
5s 3 - 4p 5 
5s 3 - 4p 2 
3s 2 — 3p 2 



5s'[l/2];-4p'[3/2] 2 3s 2 -3p 4 



3s4 — 3p 7 



3s 5 — 3p 6 
3pi — 3d 2 
3s 4 — 3p 3 



CW. In a 5 : 1 He-Ne mixture, total 

pressure 0.6 Torr, D = 8 mm. 
CW. In a 13 : 1 He-Ne mixture at a 
total pressure of 0.86 Torr in a long 
discharge tube, D = 22 mm. 
CW. In pure neon at 0.15 Torr, 

D = 15 mm. 
CW. In a He-Ne mixture in cascade 

from the well-populated Ne-3p levels. 
CW. In a He-Ne mixture, over ranges 
0.01-0.2 Torr of neon, 0.00-1.0 Torr 
of helium, D = 10 mm. 
CW. In a long discharge tube, in 
He-Ne mixture and in pure neon, 
D = 10 mm. 
CW. In a He-Ne mixture over ranges 
0.01-0.2 Torr of neon, 0.00-1.0 Torr 
of helium, D = 10 mm. 
CW. 
CW. 
CW. 
CW. 
CW. 
CW. 

CW. In a 12 : 1 He-Ne mixture at a 
total pressure of 0.65 Torr, 
D = 10 mm. Requires wavelength 
selection to suppress superradiance of 
the 3.39-/zm line. 
CW. In a He-Ne mixture over ranges 
0.01-0.2 Torr of neon, 0.00-1.0 Torr 
of helium, D = 10 mm. 
CW. 
CW. 
CW. 
CW. 

CW. In a 5 : 1 He-Ne mixture at a pZ> 
of 3.6 Torr-mm. The Ne-3s 2 level is 
selectively excited mainly by 
excitation transfer from He 2 'So 
metastables in an endothermic 
reaction, as well as by direct electron 
impact from the ground state. 97,99 
CW. 
This line exhibits very high gain. 



CW. In a He-Ne mixture over ranges 
0.01-0.2 Torr of neon, 0.00-1.0 Torr 
of helium, D = 10 mm. 

CW. 

CW. 

CW. 



129, 


12, 148, 


149, 185 


150 




151, 


12 


116, 


80, 129 


152, 


145 



116 



152, 65 



152, 12, 145 

152 

152, 12, 145 

152, 145 

152, 145 

152, 12, 145 

153 



152, 129, 141, 
145, 151 

152,141,145,151 
152,141,145,151 
152, 145 
152, 145 
145, 141, 148, 
151 



154, 47, 79, 80, 
90, 91, 93, 
95, 105, 109, 
138, 145, 148 

152, 6, 141, 145, 
151. 

145, 12, 141, 151 
145, 141 
152, 145 



208 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 




Identification 












(/xm) 




Racah 


Paschen 






Notes 




References 








6.8.2 NEON {Continued) 






4.2183 


5s'[l/2]? 


-4p'[l/2] 


3s 2 - 3p, 


CW. 


As for the 3.0720-^m line. 


153 


5.4048 


4p'[l/2] 


- 3d'[3/2]? 


3pi — 3si 


cw. 


In a 


He-Ne mixture over 


ranges 


173, 141, 145, 










0.01-0.2 Torr of neon, 0.00-1.0 Torr 


151 










of helium, D = 10 mm. 






5.6667 


4p[l/2] 


- 3d[3/2]? 


3p 3 — 3d 2 


CW. 




, 




145, 151, 152 


7.3228 


6s[3/2]2 - 


- 5p[5/2] 3 


4s 5 - 4p 9 


CW. 




,, 




145, 151, 152 


7.4211 


6s'[l/2]§ 
6s'[l/2]g 


-5p'[l/2], 

or 
- 5p'[3/2]! 


4s 3 -4p 2 (?) 

or 
4s 3 - 4p 5 


CW. 




" 




145, 152 


7.4237 


5p'[l/2], 


-4d[3/2] 2 


4p 2 - 4d 3 


CW. 




,, 




152, 145 


7.4799 


4p[3/2] 2 - 


- 3d[5/2]S 


3p 6 — 3di 


CW. 




" 




152, 141, 145, 
151, 155 


7.4994 


6s[3/2]2 - 


- 5p[5/2] 2 


4s 5 - 4p 8 


CW. 




,, 




152, 12, 141 


7.5313 


6s[3/2]? - 


- 5p[3/2], 


4s 4 - 4p 7 


CW. 


In a 


He-Ne mixture at 0.15 Torr 


151, 12 










of 


neon 


, 0.3 Torr of helium, 














D 


= 15 


mm. 






7.6163 


4p[3/2] t - 


- 3d[5/2] 2 ° 


3p 7 — 3di 


CW. 


In a 


He-Ne mixture over 


ranges 


152, 141, 145, 










0.01-0.2 Torr of neon, 0.00- 


1.0 Torr 


151 










of helium, D = 10 mm. 






7.6461 


5p'[3/2]! 


-4d[5/2] 2 ° 


4p 5 -4d, 


CW. 




,, 




152 


7.6510 


4p[5/2] 2 - 


- 3d[7/2] 3 ° 


3p 8 — 3d 4 


CW. 




,, 




141, 145, 151 


7.6925 


4p'[3/2] 2 


- 3d'[5/2]S 


3p 4 — 3si 


CW. 




,, 




152 


7.7015 


4p'[3/2] 2 


- 3d'[5/2]? 


3p 4 — 3s7 


CW. 




,, 




141, 145, 151 


7.7407 


4p[5/2] 2 - 


- 3d[3/2]S 


3p 8 - 3d 3 


CW. 




,, 




152 


7.7655 


4p'[l/2]! 


- 3d'[3/2]S 


3p 2 — 3s 4 


CW. 




,, 




141, 151 


7.7815 


6s[3/2]^ - 


- 5p[3/2]! 


4s 5 - 4p 7 


CW. 




,, 




152, 145 


7.8368 


6s[3/2]2 - 


- 5p[3/2] 2 


4s 5 - 4p 6 


CW. 




» 




152, 141, 145, 
151 


8.0088 


4p'[3/2]x 


- 3d'[5/2]S 


3p 5 — 3si'" 


CW. 




,, 




152,141,145,151 


8.0621 


4p[5/2] 3 - 


- 3d[7/2]2 


3p 9 — 3d 4 


CW. 




,, 




152,141,145,151 


8.3370 


4p'[5/2] 2 


- 3d[5/2]S 


3p 5 — 3d'/ 


CW. 




,, 




152, 145 


8.8413 


4p[5/2] 3 - 


- 3d[5/2]§ 


3p 9 — 3d" 


CW. 




,, 




152, 145 


9.0533 


6s[3/2]? - 


-5p[l/2] 


4s 4 - 4p 3 


CW. 




» 




152, 141,145,151 


or 
9.0896 


















10.0637 


4p[l/2]! - 


-3d[l/2]? 


3p 10 — 3d 5 


CW. 




,, 




152, 145 


10.981 


4p[l/2], - 


- 3d[3/2]5 


3p 10 — 3d 3 


CW. 




,, 




152,141,145,151 


11.861 


5p[l/2h- 


-5s'[l/2]§ 


4p 10 — 3s 5 


CW. 




,, 




145 


11.902 


5p[l/2] - 


-4d[3/2]? 


4p 3 - 4d 2 


CW. 




,, 




152 


12.835 


5p[1/2] - 


- 4d'[3/2]? 


4pi - 4s i 


CW. 




,, 




152, 145 


13.759* 


7s'[l/2]? 


- 6p'[3/2] 2 


5s 2 — 5p 4 


CW. 




» 




141,145 




4d'[3/2]§ 


-4f[5/2] 3 


4sJ - 4Y 


CW. 








152, 145 


14.930 




— 


— 


CW. 




,, 




145 


16.638 


5p[3/2] 2 - 


-4d[5/2]S 


4p 6 - 4dJ 


CW. 




» 




152, 145 



* This is the most likely transition to give the 13.8-/xm line; 145 selective excitation of the Ne-5s 2 state occurs via excitation 
transfer from He-2p 1 V l atoms. 98 

Note: Excitation transfer is responsible for the selective excitation of the Ne 5s 2 , 3s 2 and 2s 2 - 4 levels via excited helium 
atoms in the He l P lt He* 1 S and He* 2 3 S] states, respectively. The 1/D gain relationship (under optimum discharge exhibited 
by laser transitions from the Me-3s 2 and 2s 2 levels in the He-Ne laser) is due to the populations of these levels following the 
concentration of He 2'So and 2 3 Si metastables, which follows a 1/D relationship. The 1/D gain relationship is not duetoNe-ls 
metastables, as stated throughout the laser review and book literature. This can be deduced from an analysis of the results of 
White and Gordon, 95 (Labuda 159 ). The same 1/D gain relationship is also shown by the 0.4416-/nm and 0.3250-ju.m laser lines in 
the He-Cd ion laser. The upper levels of these lines are also selectively excited (in a Penning reaction) by helium metastable 
(He*2 3 S 1 )atoms. 160 - 162 



6 Neutral Gas Lasers 209 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 


i 


Identification 
Racah Paschen 


Notes 


References 










6.8.2 


NEON {Continued) 




16.668 


5p[3/2] 2 


-4d[5/2]§ 


4p 6 


-4d; 


CW. In a He-Ne mixture over ranges 
0.01-0.2 Torr of neon, 0.00-1 .0 
Torr of helium, D = 10 mm. 


145 


16.893 


5p[3/2], 


- 4d[5/2]^ 


4p 7 


-4d7 


CW. 


141, 145 


16.947 


5p[5/2] 2 


-4d[7/2]° 


4p 8 


-4d 4 


CW. 


, 


152, 141, 145 


17.158 


5p'[3/2] 2 


-4d'[5/2]§ 


4p 4 


- 4s','" 


CW. 


,, 


141, 145 


17.189 


5p'[3/2] 2 


-4d'[3/2]$ 


4p 4 


-4s7 


CW. 


, 


145 


17.804 


5p'[l/2], 


-4d'[3/2]S 


4p 2 


-4s'/ 


CW. 


, 


141, 145 


17.841 


5p'[3/2], 


- 4d'[5/2]? 


4p 5 


- 4s','" 


CW. 


, 


141, 145 


17.888 


5p[5/2] 3 


- 4d[7/2tf 


4p 9 


-4di 


CW. 


, 


152, 141, 145 


18.396 


5p[5/2] 2 


-4d[5/2]S 


4p 8 


-4d7 


CW. 


, 


152, 141, 145 


20.480 


6p[l/2] 


-5d[l/2]? 


5p 3 


-5d 5 


CW. 


, 


141, 145, 152 


21.752 


6p[1/2] - 


- 5d[3/2]? 


5p 3 - 


-5d 2 


CW. 


, 


141,145 


22.836 


5p[l/2], 


- 4d[3/2] 2 1 


4pio 


-4d 3 


CW. 


, 


141, 145 


25.423 


6p'[l/2] 


- 5d'[3/2]? 


5pi - 


-5s; 


CW. 


, 


141, 145 


28.053 


6p[3/2], 


-5d[l/2]§ 


5p 7 - 


-5d 6 


CW. 


, 


141, 145 


31.553 


6p[3/2] 2 


- 5d[5/2]f 


5p 5 - 


-5d', 


CW. 


, 


145 


31.928 


6p[3/2]i 


- 5d[5/2]f 


5p 7 - 


-5dT 


CW. In pure neon at 0.05 Torr, 
D = 21 mm. 


156, 157 


32.016 


6p[5/2] 2 


- 5d[7/2]^ 


5p 8 - 


-5d 4 


CW. In a He-Ne mixture over ranges 
0.01-0.2 Torr of neon, 0.00-1.0 Torr 
of helium, D = 10 mm. 


141 


32.516 


6p'[3/2] 2 


- 5d'[5/2]§ 


5p 4 - 


- 5s'," 


CW. 


145 


33.824 


6pVI2h 


- 5d'[5/2] 2 ° 


5p 5 - 


- 5s;'" 


CW. 


145 


or 




or 


or 






33.837 


6p[5/2] 3 


- 5d[7/2]2 


5p 9 - 


-5d 4 






34.552 


6p'[l/2] 1 


- 5d'[3/2]S 


5p 2 - 


-5sT 


CW. 


145 


34.679 


6p[5/2] 2 


- 5d[5/2]2 


5p 8 - 


-5dT 


CW. In pure neon at 0.05 Torr, 
D = 21 mm. 


156, 157 


35.602 


7p[l/2] 


- 6d[3/2]? 


6p 3 - 


-6d 2 


CW. 


156,6,157 


37.231 


7p'[l/2] 


-6d'[3/2]? 


6pi - 


- 6s ; 


CW. 


156, 157 


41.741 


6p[l/2], - 


- 5d[3/2]? 


5pio 


-5d 3 


CW. 


156, 157 


50.705 


7p[3/2] 2 - 


- 6d[3/2]^ 


6p 6 - 


-6d 3 


CW. 


156, 158 


52.425 


7p'[l/2]i 


- 6d'[3/2]S 


6p 2 - 


- 6s'/ 


CW. In pure neon at 0.02 Torr, 
D = 47 mm. 


158 


53.486 


7p[3/2] 2 - 


- 6d[5/2]S 


6p 6 - 


-6di 


CW. As for the 34.679-/xm line. 


156, 157 


54.019 


7p[3/2]! - 


- 6d[5/2] 2 ° 


6p 7 - 


-6dJ 


CW. In He-Ne mixture, 0.05 Torr of 
neon with 0.1 Torr of helium, 
D = 21 mm. 


156, 157 


54.117 


7p[5/2] 2 - 


- 6d[7/2]§ 


6p 8 - 


-6d 4 


CW. 


156, 157 


55.537 


7p'[3/2]! 


- 6d'[5/2]5 


6p 5 - 


- 6si"' 


CW. As for the 52.425-/zm line. 


158 


57.355 


7p[5/2] 3 - 


- 6d[7/2]S 


6p 9 - 


-6d 4 


CW. In He-Ne mixture, 0.03 Torr of 
neon with 0.07 Torr of helium, 
D = 21 mm. 


156, 157 


68.329 


7p[l/2]i - 


- 6d[3/2] 2 > 


6pio 


-6d 3 


CW. In pure neon at 0.035 Torr, 
D = 34 mm. 


155, 12 


72.108 


8p'[l/2] 


-7d'[3/2]? 


7pi- 


-7si 


CW. As for the 54.425-^m line. 


158 


85.010 


8p[3/2] 2 - 


-7d[5/2]§ 


7p 6 - 


-7d{ 


CW. As for the 68.329-jiim line. 


155, 12 


86.962 


8p'[3/2] 2 


-7d[5/2]S 


7p 4 - 


- 7s'/" 


CW. 


158 


88.471 


8p[3/2] t - 


- 7d[5/2] 2 > 


7p 9 - 


-7dJ 


CW. 


158, 12 


89.859 


8p[5/2] 3 - 


- 7d[7/2] 3 > 


7p 9 - 


-7d 4 


CW. 


158 



210 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 
(/Am) 



Identification 
Racah Paschen 



Notes 



93.02 



106.07 


10p[l/2] o -9d[3/2]? 


124.52 


9p[3/2]! - 8d[5/2]S 


or 


or 


124.76 


9p[3/2] 2 - 8d[5/2]§ 


126.1 


— 


132.8 


— 


0.706721 


4p'[3/2] 2 - 4s[3/2]2 


0.7503 


4p'[l/21o — 4ST1/21? 



0.8780* 

1.0935 
1.21** 

1.213962 

1.240275 

1.270221 

1.28f 

1.3472 

1.4093640 

1.618 

1.694058 

1.791437 



1.8167 
2.0616 
2.0986 
2.133 

2.1534 
2.2044% 

or 
2.2083 
2.313320 
2.3973% 



3d[5/2]?-4p[5/2] 3 
3d'[3/2]?-4p'[3/2] 1 

3d[3/2]?-4p[3/2] 1 
3d'[3/2]?-4p'[l/2] 1 
3d[5/2]§-4p[5/2] 2 
7d[3/2] 2 ' - 5p[3/2] 2 
3d[3/2]?-4p[l/2] 

5s[3/2]2 - 4p'[3/2] 2 
3d[3/2]^-4p[3/2] 2 
3d[l/2]?-4p[3/2] 2 



3d[1/2]§-4p[3/2] 1 
3d[7/2]S - 4p[5/2] 3 
3d[3/2] 2 '-4pT3/2] 2 
3d[l/2]?-4p[l/2] 
3d[l/2]?-4pT3/2] 1 

3d[3/2]S-4p'[l/2] 1 
3d[l/2]?-4p'[3/2], 

or 
3d[l/2]?-4p'[3/2] 2 
3d[l/2]?-4p'[l/2] 1 
3d[l/2]g-4p'[l/2] 1 



6.8.2. NEON {Continued) 



9p 3 - 9d 2 



CW. In pure neon at 0.01 Torr, 

D = 41 mm. 
CW. 
CW. 



CW. 
CW. 



6.8.3. ARGON (Figure 6.15) 



2p 3 - ls 5 
2pi — ls 2 



3di-2p 9 (?) 

3sJ — 2p 4 

3d 2 -2p 7 
3sl — 2p 2 
3d'/ - 2p 8 
7d 3 - 3p 6 
3d 2 — 2p 5 

2s 5 - 2p 3 
3d 3 - 2p 6 
3d 5 - 2p 6 

or 

3d 6 — 2p 7 
3d 4 — 2p 9 
3d 3 -2p 3 
3d 5 -2p 5 
3d 5 - 2p 4 

3d 3 — 2p 2 
3d 6 - 2p 4 

or 
3d 5 — 2p 3 
3d s — 2p 2 
3d 6 — 2p 2 



Transient line requiring short rise-time, 

high voltage, high current pulses. 
Transient line as above, observed in an 

argon-neon (helium) discharge. 

Favors very low argon pressure. 
Pulsed. In argon at 1-20 mTorr, 

D = 2.7-4.0 mm. 
Pulsed. ,, 

Pulsed. In a mixture of argon and 

helium above 200 Torr, D = 1 1 mm. 
Pulsed. Superradiant line observed in 

argon at 0.03 Torr, D = 3 mm. 
Pulsed. ,, 

Pulsed. ,, 

Pulsed. As for the 1.21-/xm line. 
CW. In argon at 0.25 Torr, D = 2.2 mm. 
Pulsed. Superradiant line in argon at 

0.04 Torr, D = 7 mm. 
CW. In argon at 0.05 Torr, D = l mm. 
CW. In 2.5 Torr of argon, D = 7 mm. 
CW. In 0.035 Torr of argon, D = l mm. 



CW. 

CW. In 0.035 Torr of argon, D = l mm. 
CW. In 0.012 Torr of argon. 
CW. In 0.01 -0.05 Torr of argon, 

D = 10 mm. 
CW. In 0.018 Torr of argon. 
CW. In 0.01-0.05 Torr of argon, 

Z) = 10mm. 

CW. 
CW. 



References 



158 

158, 12 
158 



158 
158 



89 



85 



163 

163 
120 

164 

164 

164-166 

120 

167 

126 

78,47 
78,47, 126 
78, 12,47, 165. 
166 



77 

47,78 
146, 12,77 
152 

146, 77 
152, 145, 205 



145, 126, 152 
152,145,165,205 



* This line is possibly an Ar-II line at 0.87718 fim. 
** This line is possibly the Ar-I line reported at 1.21396 ftm. 
t Possibly the same as the Ar-I line at 1.27022 ^m. 

t Enhanced by the addition of chlorine to a mixture of argon and helium. 205 

Note: Unidentified laser lines observed in a pulsed argon-mercury discharge 21 at 1.222, 1.246 and 1.276 urn have been 
placed under Laser Transitions in Mercury (Table 6.2.4). 



6 Neutral Gas Lasers 211 
TABLE 6. NEUTRAL LASER TRANSITIONS {Continued) 



I0 3 X I25i- 



I20 



II5 



CD 

tr 

Z 
Ld 



10 



05 



1 00 



95 




90 L 

Fig. 6-15. Energy-level diagram of argon, showing laser transition groups. 



212 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 



Identification 
Racah Paschen 



Notes 



References 



2.5014 

2.5494 
2.5512 
2.5634 
2.5668 
2.6843 
2.7364 
2.8202 



2.8783 
2.8843 
2.9280 
2.9796 
3.0462 
3.0996 
3.1333 
3.1346 

4.7330 
4.9160 
4.9213 
5.1216 

5.1218 
5.4680 

5.4694 
5.8477 
5.8666 

6.0531 
6.9429. 
6.9448 
7.2166 
7.8003 

or 
7.8023 
7.8063 

12.141 

or 
12.146 
15.037 

or 
15.042 
26.944 



0.3050 



6.8.3 ARGON {Continued) 



6d'[3/2]S - 6p[l/2h 6sl-4p 10 



5p[5/2] 3 

5p[l/2] 

6d'[3/2]S 

5p'[l/2] 

5p[3/2] t - 

5P-U/2L 

SpVWx 

5p[3/2] 2 - 
5p[5/2] 3 - 
5p[3/2] 2 - 
5p[l/2] - 
5p[5/2] 2 - 
5p[5/2] 2 - 
5p[5/2] 3 - 
5p[l/2]! - 
6pVI2] t 



- 3d[7/2]^ 

- 5s[3/2]? 

- 6p[5/2] 3 

- 5s'[l/2]? 
-3d[5/2]S 

- 3d'[3/2]S 

- 5s'[l/2]§ 
or 

- 5s[3/2]? 

- 5s[3/2]^ 

- 3d[5/2] 3 ° 

- 3d[3/2]? 

- 5s[3/2]? 

- 3d[5/2]£ 

- 3d[5/2] 3 ° 

- 5s[3/2]? 
-4d[5/2]S 



5PI1/2]! - 3d'[3/2]? 
6p'[3/2] 2 -4d'[3/2]S 
5d[5/2]S-4f[7/2] 3 
6p[5/2] 3 -4d[7/2] 3 

5d[7/2]§-4f[9/2] 4 
5d[7/2] 4 -4f[9/2] 5 

or 
5d[7/2] 4 -4f[9/2] 4 
6p[l/2] -6s[3/2]? 
6p[3/2] 2 - 4d[5/2]f 

4d[l/2]?-5p[5/2] 2 
4d[3/2]? - 5p'[3/2]i 
6p'[l/2],-6s'[l/2]? 
6p[l/2] 1 -6s[3/2]S 
4f[3/2] 2 -4d[3/2]° 

or 
4f[3/2] 1 -4d[3/2]g 
7s'[l/2]?-4p'[l/2], 



3p 9 — 3d 4 
3p 5 — 2s 4 
6si — 4p 9 
3p t — 2s 2 
3p 7 — 3di 
3p 2 — 3si 
3p 4 — 2s 3 
or 
3p 6 — 2s 4 
3p 9 — 2s 5 
3p 6 — 3di 
3p 5 -3d 2 
3p 8 — 2s 4 
3p 8 — 3di 
3p 9 — 3di 
3p 10 -2s 5 (?) 
4p 3 - 4di 

3pi — 3si 
4p 3 - 4si 
5dJ - 4U 
4p 9 — 4d 4 

5d 4 - 4V 
5di - 4V 

or 
5d 4 - 4V 
4p 5 — 3s 4 
4p 6 - 4di 

4d 5 - 3p 8 
4d 2 — 3p 4 
4p 2 — 3s 2 
4p 10 — 3s 5 
4X 2 -4d 3 

or 
4X!-4d 3 
4s 2 - 2p 2 



4d'[3/2]?-4f[3/2] lt2 4si-4X 



CW. In 0.01-0.05 Torr of argon, 

Z> = 10mm. 
CW. 
CW. 
CW. 
CW. 
CW. 
CW. 
CW. 



CW. 
CW. 
CW. 

CW. 
CW. 
CW. 
CW. 

CW. In 0.01-0.05 Torr of argon, 

D = 10 mm. 
CW. 
CW. 
CW. 
CW. In 0.01-0.05 Torr of argon, 

D = 10 mm. 
CW. In 0.05 Torr of argon, D = 15 mm. 
CW. 



cw. 

CW. In 0.01-0.05 Torr of argon, 

Z> = 10mm. 
CW. 
CW. 
CW. 

CW. In 0.05 Torr of argon, D = 10 mm. 
CW. 



CW. In 0.01-0.05 Torr of argon, 

Z) = 10 mm. 
CW. 



4d'[3/2]§-4f[5/2] 3 



4s'/ - 4Y CW. 

6.8.4 KRYPTON (Figure 6-16) 



152,145 

152,145 
145 
152 
145 

152, 145 
152, 145 
145, 152 



145 

152, 145 
152, 145 
152, 145 
152, 145 
152, 145 
145 
152 

152 

152, 145 
145 
152, 145 

141 
141, 145 



141, 145 
152 

152, 145 
152,145 
145 

141, 145 
145 



152 

152, 141, 145 



5d'[3/2]S - 5f [5/2] 3 5sJ - 5Y CW. In 0.05 Torr of argon, D = 10 mm. 141, 145 



Pulsed. In low pressure discharge in 
krypton. Impurity likely. 



141, 145 
85, 12, 168 



6 Neutral Gas Lasers 213 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 



Identification 
Racah Paschen 



Notes 



References 



0.8104365 5p[5/2] 2 - 5s[3/2]2 



6.8.4 KRYPTON {Continued) 

2p 8 — ls 5 Transient line requiring short rise-time, 

high voltage, high current pulses. In 
about 0.1 Torr of krypton. D = 3 mm. 
Peak current 1000 A. 



90, 89, 126 



0.8589 










Pulsed. In krypton at 1-20 mTorr, 
D = 2.7^.0 mm. 


163 


1.1457481 


6s[3/2]? - 


-5p[l/2], 


2s 4 - 


-2pio 


Pulsed. Superradiant, in 0.04 Torr of 
krypton, D = 1 mm. 


126 


1.3177412 


6s[3/2]? - 


- 5p[5/2] 2 


2s 4 - 


-2p 8 


Pulsed. Superradiant, in 0.06 Torr of 
krypton, D = l mm. 


126 


1.3622416 


4d[3/2]? - 


- 5p[5/2] 2 


3d 2 - 


-2p 8 


Pulsed. Superradiant, in 0.03 Torr of 
krypton, D = 1 mm. 


126 


1.4426793 


6s[3/2]? - 


- 5PP/2L 


2s 4 - 


-2p 7 


Pulsed. Superradiant, in 0.08 Torr of 
krypton, D = 7 mm. 


126 


1.4765471 


6s[3/2]° - 


- 5p[3/2] 2 


2s 4 - 


-2p 8 


Pulsed. Superradiant, in 0.2 Torr of 
krypton, D = 7 mm. 


126 


1.6853498 


4d[7/2]§ - 


- 5p[5/2] 3 


3d 4 - 


-2p 9 


Pulsed. Superradiant, in 0.07 Torr of 
krypton, D — 1 mm. 


126 


1.689677 


4d[l/2]? - 


-5p[l/2] 1 


3d 5 - 


-2pio 


Pulsed. Superradiant, in 0.08 Torr of 
krypton, D = 1 mm. 


78, 47, 126 


1.694 


4d[5/2]S - 


- 5PP/2], 


3dJ- 


-2p 7 


CW. In 0.05 Torr of krypton, D = l mm. 


78,47 


1.784 


4d[l/2]g - 


-5p[l/2h 


3d 6 - 


-2pio 


CW. In 0.07 Torr of krypton, D = l mm. 


78,47 


1.819 


4d'[5/2]S 


-5p'[3/2] 2 


3si"' 


-2p 2 


CW. 


78,47 


1.921 


8s[3/2]? - 


- 6p[5/2] 2 


4s 5 - 


-3p 8 


CW. In 0.035 Torr, D = l mm. 


78,47 


2.1171 


4d[3/2] 2 > - 


- 5PI3/2]! 


3d 3 - 


-2p 7 


CW. 


47, 78, 12, 151 


2.1902532 


4d[3/2]2 - 


- 5p[3/2] 2 


3d 3 - 


-2p 6 


CW. 


78, 12, 47, 151, 
169 


2.42587 


4d[l/2]? - 


- 5p[3/2] x 


3d 5 - 


-2p 7 


CW. 


146, 77 


2.523385 


4d[l/2]? - 


- 5p[3/2] 2 


3d 5 - 


-2p 6 


CW. Superradiant, in 1 .0 Torr of 
krypton, D = 7 mm. 


173, 47, 126, 
141, 145, 151 


2.6267 


4d[l/2]§- 


- 5p[3/2h 


3d 6 - 


-2p 7 


CW. In 0.02 Torr of krypton, 
D = 10 mm. 


152, 145 


2.6288 


7p[3/2] 2 - 


-4d'[5/2] 2 ° 


4p 6 - 


- 3s;'"(?) 


CW. In 0.03 Torr of krypton, D = 5 mm. 


145 


2.8618 


6p[5/2] 2 - 


- 6s[3/2]^ 


3p 8 - 


-2s 5 


CW. In 0.02 Torr of krypton, 


152, 126, 145 


or 




or 




or 


D = 10 mm. 




2.8655 


6p[5/2] 3 - 


- 6s[3/2]2 


3p 9 - 


-2s 5 






2.9845 


6p'[l/2h 


- 5d[5/2]S 


3p 3 - 


-4dl 


CW. 


152, 145 


2.9878 


6p'[3/2] x 


-6s'[l/2]§ 


3p 4 - 


-2s 3 


CW. In 0.03 Torr of krypton, 
D = 15 mm. 


145 


3.0536 


6p'[3/2]! 


- 5d[5/2]S 


3p 4 - 


-4dl 


CW. In 0.02 Torr of krypton, 
D = 10 mm. 


145, 152 


3.0672 


6p[l/2]! - 


- 6s[3/2]§ 


3pio 


-2s 5 


CW. In 0.03 Torr of krypton, 
D = 15 mm. 


141, 145, 151 


3.1515 


6p'[l/2] 


- 5d[3/2]? 


3pi - 


-4d 2 


CW. In 0.02 Torr of krypton, 
D = 10 mm. 


152, 145 


3.3409 


6p[l/2h - 


-6s[3/2]? 


3pio 


— 2s 4 


CW. In 0.03 Torr of krypton, 
D — 15 mm. 


145 


3.3419 


4d[l/2]? - 


-5p[l/2] 


3d 5 - 


-2p 5 


CW. In 0.02 Torr of krypton, 
D = 10 mm. 


152, 151 


3.4680 


7s[3/2]? - 


-6p[l/2]! 


3s 4 - 


-3p 10 


CW. 


152, 145 


3.4883 


7s[3/2]2 - 


-6P11/2]! 


3s 5 - 


-3p 3 


CW. 


152, 145 



214 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 


Identification 
Racah Paschen 


Notes 


References 






6.8.4 KRYPTON {Continued) 






3.4895 


swuw-wim,. 


4d 2 - 3p 3 


CW. In 0.03 Torr of krypton, 
D = 15 mm. 


145 




4.3748 
4.3767 


5d[3/2]? - 6p[3/2] 2 
7s[3/2]S - 6p[3/2] 2 


4d 2 — 3p 6 

3s 5 — 3p 6 


CW. 

CW. In 0.02 Torr of krypton, 
D = 10 mm. 


145, 
152 


141, 151 


4.8773 
4.8832 
5.3000 


4d[3/2]? - Sp'P/2]! 
5d[5/2]2 - 6p[5/2] 3 
5d[3/2]?-6p[l/2] 


3d 2 — 2p 4 
4d" — 3p 9 
4d 2 - 3p 5 


CW. 
CW. 
CW. In 0.02 Torr of krypton, 


152, 
145 

152, 


145 
141, 145 


or 


or 


or 


D = 10 mm. 






5.3019 
5.5700 
5.5863 


5d[3/2]S - 6p[5/2] 2 
5d[7/2]S - 6p[5/2] 2 
6d[7/2]2-4f[9/2] 5 


4d 3 - 3p 8 
4d 4 — 3p 8 
5d 4 - 4U 


CW. 

CW. In 0.03 Torr of krypton, 
D = 15 mm. 


152, 
145, 


12, 145 
141, 151 


5.6306 
7.0581 


6d[3/2]S-4f[5/2] 3 
4f[7/2] 3 .4-5d[7/2]2 


5d 3 -4T 
4W - 4d 4 


CW. 

CW. In 0.02 Torr of krypton, 
D = 10 mm. 


145, 
152, 


141, 151 
145 



0.840919 



0.904545 



2.026229 



2.3200 



2.4825 



6p[3/2h - 6s[3/2]S 



6p[5/2] 2 - 6s[3/2]§ 



0.97997 


6PU/2]! - 6s[3/2]^ 


2pi — ls 5 


1.0634 


— 


— 


1.0950 





— 


1.365701 


7s[3/2]? - 6p[5/2] 2 


2s 4 — 2p 9 


1.605327 


7sf3/2]? - 6p[3/2] 2 


2s 4 — 2p 6 


1.732578 


5d[3/2]? - 6p[5/2] 2 


3d 2 — 2p 9 



5d[3/2]? - 6p[3/2]! 



5d[5/2] 3 °-6p[5/2] 2 



5d[5/2]g - 6p[5/2] 3 



6.8.5 XENON (Figure 6-17) 

2p 7 — ls 5 Transient superradiant line requiring 

short rise-time, high voltage, high 
current pulses. In 0.04 Torr of xenon, 
D = 1 mm. 
2p 9 — ls 5 Transient, superradiant line. As above, 

in 0.12 Torr of xenon. 

Pulsed. In 0.2-0.4 Torr of xenon. 

Pulsed. In 1-20 mTorr of xenon, 
D = 2.74.0mm. 

Pulsed. ,, 

Pulsed. Superradiant, in 0.04 Torr of 
xenon, D = 7 mm. 

Pulsed. Superradiant, in 0.1 Torr of 
xenon, D = 1 mm. 

Pulsed. Superradiant, in 0.15 Torr of 
xenon, D = 7 mm, also CW in 
0.03-0. 1 Torr of xenon, D = 4 or 
7 mm. 
3d 2 — 2p 7 CW. Superradiant line in even short 

discharge tubes. The gain in a 5-mm 
bore tube is more than 45 dB/m. In a 
few mTorr of xenon, or in a 100 : 1 
He-Xe mixture at a total pressure of 
about 10 Torr, D = 5 mm. To avoid 
cataphoretic effects in He-Xe mixture 
rf-excitation is necessary. Clean-up of 
xenon is a problem. 178,180 
3d/ - 2p 9 CW. In 0.01-0.04 Torr of xenon, 

helium also added to about 1 Torr, 
D = 1 mm. 
3d{ - 2p 8 CW. In 0.03-0.1 Torr of xenon, 

D = 4 or 7 mm. 



163, 126 



90, 126 

90 
163 

163 
126 

126 

170, 126, 177 



78, 12, 47, 126, 
169-177, 185 



173, 141, 169, 
177, 185 

170, 177 



6 Neutral Gas Lasers 



215 



5 



CM 

OJ 
CM 

or 

CM 



CM 



q!° 



CM 



CM 



Q. 
CM 



CM 



^3 


Q. 


s 


CM 


.5 


CM 


-»-«> 


■»» 




or 


O 


CM 


v — ' 


CM 


V) 


to 


Z 


Q. 


o 


CM 


hH 


CM 


H 


^ 




Q. 


£ 


CM 


2S 


z M 


H 


UJ^ 




a:o 


Pti 


< ~ 


W 


Q. 


(/) 




^ 




J 




$ 




04 




H 




P 




W 




Z 




vo 




W 




hJ 






( U W0) A9H3N3 




m 


vi a 


N 


6b.2 








b "55 




c 



O 



IO 

o 



o 
o 



to 

0) 



o 



m 

GO 



♦~(,JW)) A9H3N3 



O 



m 



C en 

^ 3 

vd 2 

*7 60 

*> c 
.5J.-2 

E ■« 
c 



216 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 



Identification 
Racah Paschen 



Notes 



References 



6.8.5 XENON {Continued) 



2.6276 


5d[5/2]S - 


-6p[5/2] 2 


3d'/ 


-2p 9 


CW. As for the 2.3200-/xm line. 


173, 141, 169, 
177, 179 


2.651093 


5d[3/2]? - 


-6p[l/2] 


3d 2 


-2p 5 


CW. 


173, 126, 169, 
170, 174, 177 
185 


2.6608 


5d'[3/2]? 


- 6p'[l/2] 


3s/- 


-2 Pl 


CW. 


141, 169 


3.1078 


5d[5/2]§ - 


- 6p[3/2] 2 


3di- 


-2p 6 


CW. 


173, 141, 169, 
174, 177, 179 
185 


3.27459 


5d[3/2]S - 


- 6p[l/2]i 


3d 3 - 


-2pio 


CW. In a 250 : 1 He-Xe mixture in an 
rf-discharge at about 0.4 Torr, 
D = U mm. 185 


169, 77, 146, 
177, 179, 185 


3.3676 


5d[5/2]? - 


- 6PP/2]! 


3d'/- 


-2p 7 


CW. In 0.01-0.04 Torr of xenon, 
helium added to 1 Torr, D = 1 mm. 


173, 141, 169, 
174, 177, 185 


3.4345 


7p[5/2] 2 - 


- 7s[3/2]? 


3p 9 - 


-2s* 


CW. 


141, 12, 145 


3.5080 


5d[7/2] 3 ° - 


- 6p[5/2] 2 


3d 4 - 


-2p 9 


CW. Superradiant line in even short 
discharge tubes, gain more than 70 
dB/m in a 2.6-mm tube. 177 In a few to 
tens of mTorr of xenon, and with 


173,47, 141, 
151, 169, 174, 
175, 177-183, 
185 



3.6219 

3.6518 
3.6798 



3.6859 

3.8697 
3.8950 
3.9966 

4.1527. 
4.5393 
4.6109 
5.3568 



5.5754 



5d'[3/2]§-7p[3/2] 2 3si"'-3p6 



7p[l/2]! - 7s[3/2]S 
5d[l/2]?-6p[l/2]x 



5d[5/2]2 - 6p[3/2] 2 

5d'[5/2]§ - 6p'[3/2] 2 

5d[7/2]f-6p[5/2] 3 

5d[l/2]8-6p[l/2h 

5d'[5/2]2 - 7p[3/2h 
5d[3/2]? - 6p[5/2] 2 
5dVI2]°2-6p'[\12h 
5d[l/2]?-6p[5/2] 2 



5d[7/2]2 - 6p[5/2] 3 



3p 10 — 2s 5 
3d 5 — 2pio 



3d'/ - 2p 6 

3s'/-2p 3 
3d 4 - 2p 8 
3d 6 — 2pio 

3s'/ — 3p 7 
3d 3 - 2p 9 
3s'/" — 2p 2 
3d 5 - 2p 9 



3d 4 - 2p 8 



6.384 


8p[3/2] 2 - 8s[3/2]S 


4p 6 - 


- 3s 5 


7.3167 


sdp^-epp^h 


3d 3 - 


-2p 7 


8.191 


8p[l/2]! - 8s[3/2]? 


4pio 


— 3s 4 


9.0065 


5d[3/2]2 - 6p[3/2] 2 


2d 3 - 


-2p 6 



9.7029 



5d[l/2]?-6p[3/2]! 



3d 5 - 2p 7 



helium to about 10 Torr with 

D = 5 mm. Clean-up of xenon is a 

problem. 178 - 180 
CW. In 0.01-0.04 Torr of xenon, helium 

up to 1.0 Torr, D = 1 mm. 
In 0.02 Torr of xenon, D = 7 mm. 
CW. In 0.01-0.04 Torr of xenon, 

helium added up to 1.0 Torr, 

D — 1 mm. 
CW. 

CW. 
CW. 
CW. 

CW. 
CW. 
CW. 
CW. In 0.01 Torr of Xenon, 0.1 Torr of 

helium, D = 10 mm. Suppression of 

the 3.508-/xm line necessary. 
CW. In 0.01-0.04 Torr of xenon, 

helium added up to 1.0 Torr, 

D = 1 mm. 
CW. In a few tens of mTorr of xenon, 

D = 4 or 8 mm. 
CW. As for the 5.5754-ju,m line. 

CW. As for the 6.384-/x.m line. 
CW. As for the 5.5754-^m line. 

CW. 



141 

145 

173, 141, 179 



173, 141, 174, 

177 
141, 179 
173, 141, 177 
171, 141, 174, 

175 
141, 179 
153, 179 
141 
153 



173, 47, 141, 
151, 174, 179 

177 

173, 141, 174, 

177, 179 
177 
173, 12, 141, 

174, 179 
173, 141 



6 Neutral Gas Lasers 
TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



217 



Wavelength 
(fim) 



Racah 



Identification 



Paschen 



Notes 



References 



11.299 



12.266 
12.917 
18.506 
75.5778 



8p[3/2]? - 5d'[3/2] 2 

or 
5d'[5/2]!-4f|?/2] 4 
5d[l/2]8-6p[3/2h 
5d[l/2]?-6p[3/2] 2 
5d'[3/2]S-4f[5/2] 3 
6p'[3/2],-5d[l/2]? 



6.8.5 XENON (Continued) 

4p 7 — 3s','" CW. As for the 5.5754-/um line, 
or 

3s{"-4Z 

3d 6 - 2p 7 CW. 

3d 5 -2p 6 CW. 

3s','" -4U CW. 

2p 5 - 3d 5 CW. In a 100 : 1 He-Xe mixture at 

35 mTorr of xenon, or in a 3 : 1 
Kr-Xe mixture at 15-20 mTorr of 
xenon, D = 6 mm. 



141, 145 



173, 141 
173, 141 
141, 145 
184 



Wavelength 



Likely 
Species 



Occurrence 



Excitation 
if not pulsed 



References 



6.9 UNIDENTIFIED, POSSIBLE NEUTRAL LASER TRANSITIONS 



0.247718 


Xe 


0.269182 


Xe 


0.274139 


Kr 


0.304970 


— 


0.335004 


Xe 


0.34836 


Xe 


0.3545 


Hg or Ar 


0.364546 


Xe 


0.366920 


Xe 


0.3760 


— 


0.380327 


Xe 


0.397293 


Xe 


0.46453 


— 


0.465040 


— 


0.4750 


N,Hg or 


0.4764 


Ar (or Hg II) 


0.495410 


— 


0.521962 


S 


0.5440 


— 


0.5500 


o 


0.5540 


o 


0.5690 


0(11?) 


0.58525 


Ne 


0.595573 


O or Xe 


0.6350 


Te 


0.7065 


Hg or Ar 



0.75035 



Ar 



0.8390 


Cd (II?) 


0.8408 


Xe 


0.8569 


Xe 



In xenon at 0.001-0.1 Torr, D = 4 mm. 

In krypton at 0.001-0.1 Torr, D = 4 mm. 
In krypton at low pressure, impurity likely. 
In xenon at 0.001-0.1 Torr, D = 4 mm. 
In xenon, favors pressure higher than Xe-II 

lines. 
In mercury-argon mixture at low pressure. 
In xenon at 0.001-0.1 Torr, D = 4 mm. 

In xenon at low pressure, impurity likely. 
In xenon at 0.001-0.01 Torr, D = 4 mm. 

In argon at low pressure, weak line. 

In xenon. 

In mercury-nitrogen mixture at 1-20 mTorr, 

D = 3 mm. 
In a mixture of argon and mercury, with 

argon at 0.1 Torr, D = 6 mm. 
In xenon. 

In sulfur dioxide or hexafluoride. 
In mercury-nitrogen mixture. 



In carbon monoxide at 1 1-20 mTorr, D = 3 mm. 
In a neon-argon mixture, requires argon for 

oscillation, this is likely the transient Ne 

(2p, - ls 2 )-line at 0.5852488 /xm. 
In air or xenon. 
In a tellurium-neon mixture. 
In mercury-argon mixture at low pressure, 

D = 3 mm. 
In argon-neon mixture at low pressures, possibly 

the Ar (2px - 2s 2 )-line at 0.7503867 /xm. 
In cadmium-helium mixture. 
In xenon at 1-20 mTorr, D = 2.7-4 mm. 



CW 



168 
168 
168 
85, 168 

187, 168 
85 

17 

168 

168 

85 

168 

168 

188, 85 
85 

41 

27 

85 
56 
41 
41 
41 
41 
85 



85 

189 

17 

85 

16 

163 

163 



218 Handbook of Lasers 

TABLE 6. NEUTRAL LASER TRANSITIONS (Continued) 



Wavelength 

(H 



Likely 
Species 



Occurrence 



Excitation, 
if not pulsed 



References 



6.9 UNIDENTIFIED, POSSIBLE NEUTRAL LASER TRANSITIONS (Continued) 



0.882045 


O 


0.980 


I 


1.01 


I 


1.06 


I 


1.065 


s 


1.0935 


Ar 


1.0950 


Xe 


1.1869 


Cd 


1.222 


Hg 


1.2246 


Hg 


1.2545 


Hg 


1.2760 


Hg 


1.2981 


Hg 


1.3655 


Hg 


1.45423 


N 


1.977 


CI 


2.021 


CI 


2.499 


— 


2.535 


— 


2.602 


— 


2.784 


— 


3.7942 


N 


3.801 


— 


3.8154 


N 


10.604 


— 


14.78 


— 


15.04 


— 


15.08 


— 


15.41 


— 


15.47 


— 


18.21 


— 


21.46 


— 


22.54 


— 


22.71 


— 


23.68 


— 


23.86 


— 


24.92 


— 


25.12 


— 


26.27 


— 


30.69 


— 


31.47 


— 


31.92 


— 


32.13 


• — 


126.100 


Ne 


132.800 


Ne 



(II?) 



In helium-nitrogen, or neon-carbon dioxide 

mixtures at 4 Torr, D = 15 mm. 
In a mixture of iodine vapor and helium. 



In pure sulfur hexafluoride, and with helium. 

In argon at 1-20 mTorr, D = 2.7-4.0 mm. 

In xenon at 1-20 mTorr, D = 2.7-4.0 mm. 

In mixtures of cadmium and neon, or cadmium and 

helium, D= 12 mm. 
In a mercury-argon mixture. 



29 



In a mercury-helium mixture, D 
In a mercury-argon mixture. 
In a mercury-helium mixture. 



15 mm. 



In a nitrogen-helium mixture. 
In a mixture of freon (CC1 2 F 2 ) and helium at 
3.3 Torr. 



In a nitrogen-helium mixture. 

In a mixture of freon (CC1 2 F 2 ) and helium 

at 3.3 Torr. 
In a nitrogen-helium mixture. 
In CBrF 3 and helium mixture at 2.8 Torr. 
In ammonia at 0.5-1.0 Torr, D = 10 cm. 



Ne In pure neon at 0.01 Torr, D = 47 mm. 






69 


— 


69 


cw 


33,57 


— 


163 


— 


163 


— 


16 





21, 17 


— 


21, 17 


— 


19 


— 


21, 17 


— 


19 


— 


19 


— 


43 


cw 


65 


cw 


65 


cw 


65 


cw 


65 


cw 


65 


cw 


65 


— 


43 


cw 


65 





43 


cw 


65 


— 


190 





190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


— 


190 


cw 


158 


cw 


158 



6 Neutral Gas Lasers 219 

SPECIFIC SELECTIVE EXCITATION MECHANISMS 

Excitation Transfer (atom-atom) 

This so-called "collision of the second kind" involves the transfer of potential energy from an 
excited atom to another atom in a collision. The reaction is considered to be 

A' + B < > A + B' + A^, (1) 

where A£ M is the difference in potential energy at infinite separation between the excited species A' and 
B', and A and B can be (and are generally) ground state atoms. When A' is a metastable species (A*) 
and B' can decay radiatively the reaction proceeds in the forward direction. Experimentally it has been 
found that the probability of excitation transfer occurring in a collision appears to be dependent on at 
least four factors: 

1. the magnitude of AE X , 

2. spin conservation (the Wigner spin rule), 

3. the size of the colliding atoms, and 

4. the relative velocity of the colliding atoms A' and B (determined by the gas temperature (T $ ) 
of the discharge and the mass of the colliding atoms). 

Theory predicts that with AE^ -> (a resonant collision) cross sections two orders of magnitude 
larger than gas kinetic are realized. With AE^^OA eV, the cross section for excitation transfer is 
negligible. 198 

Total spin conservation (AS = 0) is favored in a collision involving excitation transfer. Given the 
reactions 

_ * AmHB'crDtAE., (2a) 

A'(tt) + B(ti) CT^ 

^-* AttD + B'CtDlAE., 

(2b) 

(2a) is the more likely reaction channel. 

Excitation transfer, which occurs in the He-Ne laser between at least three excited states of helium 
and neon, provides most of the information on the importance of the four factors (1) to (4). The three 
energy-coincidences between excited states of helium and neon, which lead to three s-p groups of laser 
transitions, are shown in Figure 6-18. The helium states involved are the 2p'P^, 2s 1 S and 2s 3 Sj. The 
2s 1 S and 2s 3 Sj states are metastable (He* 2'S and He* 2 3 S!) and lead to strong selective excitation of 
the Ne-5s and Ne-4s levels (3s and 2s in Paschen notation). 

Detailed energy-coincidences between the He* 2^0 and He* 2 3 S, states and neon are given in 
Figures 6-19 and 6-20. Figure 6-19 illustrates the energy-level-coincidence for the excitation-transfer 
reaction from He 2'S metastables to the Ne-3s states. Here preferential selective excitation of the 
Ne-3s 2 level occurs in the endothermic reaction 

He* 2 1 S (U) + Ne l S (U) > He ^U) + Ne 3s 2 (f|) - A^ (386 cm" 1 ), (3) 

in which total spin is conserved, and a AE^ of 386 cm -1 (about 2 kT) has to be provided in kinetic energy 
supplied by the gas discharge. 

Figure 6-20 illustrates the similar coincidence between He 2 3 Sj metastables and the 2s-states 
of neon. Unlike excitation transfer to the 3s-levels, selective excitation is more evenly distributed to all 
the four Ne-2s levels. 97 On the basis of energy-level coincidences, in 

He* 2 3 S 1 (tt) + Ne ! S (U) ► He l S (U) + Ne 2s 2 , 3>4 , 5 + A£ 00 (313 - 1247 cm" 1 ), (4) 

since the reaction is exothermic (with AE^ positive), kinetic energy does not have to be supplied by the 
gas for the reaction to proceed. Although AE^ of 1247 cm" 1 for the coincidence with the Ne-2s 5 level 
is larger than the AE X of 800 cm -1 (0.1 eV) — when excitation transfer is predicted to be negligible — 
selective excitation to this state from He 2 3 S t metastables does occur. In (4) total spin is conserved in 
excitation transfer to three of the Ne states (2s 3 , 2s 4 and 2s 5 ). 



220 Handbook of Lasers 
HELIUM 
NO. OF LEVELS 2 2 4 



NEON 
6 4 8 




Fig. 6-18. Energy-level diagram for neon, showing groups of laser transitions observed in a He-Ne mixture and energy 
coincidence with He (2 3 Sj, 2'S , 2 3 P 2 ,i, and 2'Pi) levels. (This figure is a modification of a figure in [141].) 

Jones and Robertson" have shown experimentally that the cross section (a) for excitation transfer 
between He* 2'S and He* 2 3 S t atoms and ground-state neon atoms follows the relationship 

a = a exp ( - EJkT). (5) 

Plots of the experimental results which lead to this relationship are given in Figures 6-21 and 6-22. 
In Eq. (5) E a has the form of an activation energy (or dissociation energy) in which E a + AE^ . This 
observed relationship would indicate that the interaction potentials between the He* 2 3 S 1 and Ne 1 S 
states and He* 2'S and Ne 1 S states have the form represented in Figures 6-23a and 6-23b respectively. 
It follows that it is the shape of the interaction potentials close-to and at the collision that determines to 
a large extent the probability of excitation transfer. 



6 Neutral Gas Lasers 221 



HELIUM 



NEON 



66,27 




Fig. 6-19. He 2 1 So metastable state energy-level coincidence with neon 3s-levels. 



HELIUM 



NEON 



160,000 




Fig. 6-20. He 2 3 Sx metastable state energy-level coincidence with neon 2s-levels. 



222 



Handbook of Lasers 



He(2'S) +Ne 



He +Ne(3.s) 



a * «r e - 
Ea =0.034 «V 
<r =11.5 X I0 1 




8 
^'(^"'x 10 ) 

Fig. 6-21. Variation of cross-section with gas temperature for excita- 
tion transfer from He 2'S metastables to the Ne-3s 2 level. 



He^S) +Ne-*-He+Ne(2s) 




f 1 (V'x I0 -3 ) 

Fig. 6-22. Variation of cross-section with gas temperature for excita- 
tion transfer from He 2 3 Si metastables to the Ne-2s levels. 



6 Neutral Gas Lasers 



223 




Ard 




00 



v CO 



NUCLEAR SEPARATION 



NUCLEAR SEPARATION 



Fig. 6-23. Illustration of the possible shape of molecular interaction potentials to explain the activation-energy 
behavior of excitation transfer between helium and neon, for (a) the exothermic reaction (4) and (b) the endothermic 
reaction (3). 

Dissociative Excitation Transfer (atom-molecule) 

This takes the form 



M' + AB 



M + A' + B + kinetic energy 
M + A + B' + kinetic energy 



(6a) 
(6b) 



where M' is an excited state (usually metastable M*). In these reactions it is assumed that relatively long 
range interactions between M' and the molecule AB cause vertical transitions between the ground state 
and repulsive states (AB) + or (AB)' (see Figure 6-24). Since several repulsive states can exist in the 
vicinity of M' and since more than two atoms are involved in the collision, there is no strong requirement 
for close energy-coincidence as in atom-atom excitation transfer. Any excess potential energy appears as 
kinetic energy of the dissociated atoms A' or B'. 

In the Ne-0 2 laser, dissociative excitation transfer occurs via the reaction 



Ne* + O, 



-► Ne , S + O + O'(3p 3 P) + K.E., 



(7) 



leading to direct selective excitation of the 3p 3 P triplet state of atomic oxygen and population inversion 
occurring between the O-I 3p 3 P and 3s 3 Si states. (Figure 6-25.) 

In the Ar-0 2 laser, dissociative excitation transfer occurs via reactions 



Ar* + 2 



Ar % + O + O' (2%) + K.E. 
Ar % + O + O' (2^2) + K.E. 



(8a) 



(8b) 



Subsequently inelastic electron collisions with atoms in the O-I 2'S and — 2'D 2 states leads to popu- 
lation inversion occurring between the O-I 3p 3 P and 3s 3 S levels. 12 ' 46 



ATOM 



MOLECULE 



>- 
o 

UJ 

z 



0-M 




A+B 



M+A'+B or 
M+A+B' plusK.E. 



A' + B or 

A + B' 

A+B 



NUCLEAR SEPARATION (r) 
Ay oo 



Fig. 6-24. Molecular potentials illustrating the dissociation of a diatomic molecule into repulsive states in dissociative 
exatation transfer. The dashed-curves represent a number of repulsive molecular potentials, which can terminate on 
common dissociation limits. M ' indicates a metastable state. 



22 
20 
18 
16 

il4 

> 

4) 

I 2 



Ne' 



Ne* 



Kr 



>- 
o 
or 
uj I 



LA* 
Kr* 



UJ 




0+0 



LASER LINE AT 
+ 0.8446^m 



0~+0+ 
0+0(3 3 P) 



0+0(3 5 P) 



Wq 0+0(33s) 0^^) 



A/ — i 




0+0 (2*S) /b-1300/xm 




IMPACT 



0+0 (2 1 D) 



J 



0(2 3 P)+0(2 3 P) 




DIFFUSION 

I 



At 



NUCLEAR SEPARATION (A) 



OO 



Fig. 6-25. Partial energy-levels relevant to the neon-oxygen and argon-oxygen laser operating at 0.8446 urn The 
dominant excitation paths are indicated by the arrows. (Ref. 46) 



6 Neutral Gas Lasers 



225 



11835.61cm" 1 

844.676 nm 

1 

0.10 cm" 1 — H-M 



l « »| 0.10 cm" 1 
I— 0.07 cm -1 




SPONTANEOUS 
EMISSION 01 
3p 



2 SPONTANEOUS 
EMISSION 01 

3 P 



Fig. 6-26. Oscillation on four lines in the oxygen triplet at 0.8446 jum in Ar-Br 2 and Ar-0 2 lasers shown relative to 
spontaneous emission lines of Br-I and O-I. (From [48] by permission of the Optical Society of America.) 

Oscillation at 0.8446 /mi in a mixture of bromine and helium or neon, with oxygen as an impurity 
is observed at four wavelengths in the wavelength interval occupied by spontaneous emission of the 
O-l(3p 3 P , 2 ,i - 3s 3 S?) triplet and close to the Br-I line at 0.844655 fim (Figure 6-26). Oscillation occurs 
at wavelengths displaced from the line centers of lines from the 3p 3 P 2 - 3s 3 S° t and 3p 3 P t - 3s 3 Sj 
transitions. Oscillation is prevented at the line centers by strong radiation trapping, but is made possible 
off-center by the extensive line-width of each component under which gain is possible. The large line- 
width of the oxygen triplet (more than five times that expected for the gas temperature in the discharge) 
is due to the large amounts of kinetic energy carried by excited 3p 3 P atoms following dissociative ex- 
citation-transfer. 49 

Optical Pumping 

If the center of a strong line falls within the Doppler half-width of a resonance transition, selective 
excitation of the resonance state is possible. An earlier figure, Figure 6-6, shows energy levels pertinent to 
the cesium laser. This laser is optically pumped by the strong 3 3 P 2 - 3^ helium line at 0.3888 /mi. 
The coincidence of the He-I line in spontaneous emission and the (6s 2 S 1/2 - 8p 2 P° 1/2 ) cesium resonance 
line at 0.388851 /mi is illustrated in Figure 6-27. Selective excitation of the 8P 1/2 -state leads to population 
inversion being realized between it and the 8S 1/2 and 6D 3/2 -states. 

Optical pumping leading to population inversion can also occur from states other than the ground 
state, if the excited state is well populated. 136 

Electron Impact Excitation 

If a strongly allowed optical transition connects the ground state with an excited state, it follows 
from the Born approximation, 198 where electron exchange can be neglected, that selective excitation of 
that excited state can occur in inelastic electron-impact collisions. In the noble gases the main selective 
excitation from the ground-state occurs through the reactions, 



(np) 6 + e" + K.E. 



(np) 5 ms + e 
(np) 5 md + e 



(9a) 
(9b) 



226 Handbook of Lasers 



HYPERFINE STRUCTURE 
OF THE Cs 0.3888506-/t 
LINE 




SPONTANEOUS EMISSION 
LINE-SHAPE OF THE 
He-I 0.3888- M LINE 



Fig. 6-27. Coincidence of the line-shapes of the Cs resonance line at 0.388851 ^m and the He-I 
(3 3 P-3 3 S,) line at 0.3888 /xm. (Ref. 13) 



(np) 5 fr(n+2)s S 



(npP(n+3)s 



(np) 5 (n+2)p 



(np) 5 IONIZATION LIMIT 
(np) 5 (n+2)d 



^np) 5 ^^ 



2 LEVELS 




l)d 



(np)° GROUND STATE 



Fig. 6-28. Schematic indication of electron configurations relevant to pure neon, argon, krypton and xenon lasers. 
The dominant excitation paths are indicated by the arrows. (Ref. 12) 



6 Neutral Gas Lasers 



227 



where m = n + \, n + 2, etc., and n = 2 for Ne, 3 for Ar, 4 for Kr and 5 for Xe. Under pZ)-discharge 
conditions sufficient to produce radiation trapping on the resonance state and low enough to prevent 
excitation transfer to other electron configurations in collisions, radiative decay can only occur through 
the transitions labeled LASER in Figure 6-28. 12 This type of selective excitation in a system, where 
radiative decay of the lower laser level is allowed and lifetimes are favorable, can lead to the realization 
of continuous oscillation. 

A number of gas laser systems selectively excited by electron impact are self-terminating or transient 
in operation. Laser systems that exhibit very high gain and are transient occur in neutral species in Pb, 
Cu. Au. Ca. Sr and Mn. as well as in the noble gases He, Ne, Ar, Kr and Xe. Figure 6-29, a partial 
energy-level diagram for a typical transient laser, shows that the upper laser level 1 is excited by direct 
electron impact from the ground state and that the lower laser level 2 is metastable (or quasi-metastable). 
In such a 3-level system, given rapid excitation of level 1, population inversion between levels 1 and 2 is 
only possible for times less than the effective radiative lifetime of the upper laser level, due to the rapid 
build-up of population in the lower laser level. 5 

Energy levels relevant to the 0.7229-//m transient lead-vapor laser are shown in Figure 6-30. In the 
noble gases in which transient oscillation occurs on p-s transitions, selective excitation of the p-levels 
occurs by radiative cascading from higher levels as well as by direct electron impact from the ground 
state. Transient laser transitions observed in neon are shown in Figure 6-31. 

Radiative Cascade-Pumping 

Cascading through strong laser transitions can be used to provide selective excitation of levels 
having the same parity as the ground state, which do not favor excitation by direct electron impact. In 
the He-Ne laser, cascade pumping occurs via strong s-p transitions from the well-populated Ne-3s 2 level 
to give selective excitation of the Ne-3p levels, and oscillation occurs in the near-infrared on a number 
of 3p-2s transitions at about 2 microns. As illustrated in Figure 6-32, extensive pumping of the 3p-levels 
is followed by cascade-pumping of the Ne-2s levels, which gives population inversion on a number 
of 2s-2p transitions and oscillation in the near-infrared around 1 .2 microns. 













I 


i 

z 
o 

»- 
< 

o 

X 

UJ 

1- 
o 

z 

z 
o 
or 

i- 
o 

UJ 

_l 

Ul 

1- 
o 

UJ 

or 
o 


I 

UJ 

z 
_l 

UJ 

o 

z 
< 
z 
o 

(O 

UJ 

tr 

1 




Xlaser transition 


1 

>- 
o 

Ld 


1 1 1 2 

♦ ♦ ♦ 

1 1 1 


UJ 




DIFFUSION TO WALLS 
AND ATOM -ATOM 
DE-ACTIVATION COLLISIONS 




' 


* ♦ ♦ 
1 1 1 

♦ 1 « 
1 l 1 
» ♦ * 



GROUND STATE OF ATOM 

Fig. 6-29. Generalized partial energy-level diagram for 
a transient laser. 



> 3- 



I — 



0— J 



3 P, 6$ 2 6p7s 



0.7229,* 
LASER LINE 




6s*6p' 



0.2833/x 

RESONANCE LINE 



>P Q 6s<6p* 



Fig. 6-30. Energy levels relevant to the 0.7229-yum 
transient lead-laser, showing dominant electron-impact exci- 
tation-path and 0.2833-/u.m resonance line. 



228 



Handbook of Lasers 



22r- 



IONIZATION LIMIT 



CASCADING FROM S-LEVELS 




3-METASTABLE 
5 -META STABLE 



GROUND STATE 



Fig. 6-31. Energy levels and excitation paths relevant to observed transient 
laser transitions in neon. 



Charge Neutralization (ion-ion recombination) 

Charge neutralization takes the general form 

A + +B" T^ 



A' + B + kinetic energy. 
A + B' + kinetic energy. 



(10a) 



(10b) 



The excess energy appears as kinetic energy of either of the neutralized particles A' or B' of about 1 eV. 
Given a particular A + and B~ there is a strong preference for A' and B or A and B'. 198 
In the pulsed sodium-hydrogen laser selective excitation occurs via the reaction 



Na + + H 



-> Na'(4s) + H, 



with H supplied in the electron-molecule dissociation-reaction 

H~ +H. 

H 2 + e" > H"+H\ 

H" + H + +e". 



(11) 

(12a) 
(12b) 
(12c) 



In a gaseous discharge above a pressure of a few Torr, recombination of positive and negative ions 
is believed to be via 3-body processes. 199 A number of lasers operate in the afterglow of high-pressure 
discharges, where electron-ion recombination is the selective excitation mechanism. 

Selective excitation in the pure oxygen laser operating in the afterglow of a pulsed discharge 53 
occurs in the electron-ion recombination reactions 



e" +0 2 + 
e+0 3 + 



->■ 0'(3p) + O + kinetic energy, 
-> 0'(3p) + 2 + kinetic energy. 



(13) 
(14) 



X 10' 



165 



160 



o 
cr 

UJ 



55 



150 



He 



* i 

He 2'S 



0^ 



6 Neutral Gas Lasers 229 



Ne 



3s 2 /3.39I3/X(SUPERRADIANT LINE) 
.3342/1 (STRONG LINE) 



He»2 3 S, 2s 




Fig. 6-32. Neon 3p-2s and 2s-2p laser transitions observed in cascade following selective exci- 
tation of the 3p 4 and 3p 5 levels by the strong 3.391 3-jLtm and 3.3342-ju.m Ne-I lines. 



Electron-ion recombination is probably responsible for selective excitation and laser oscillation in 
the afterglow of pulsed, high-pressure discharges in mixtures of noble gases. In two specific cases, the 
reactions 



and 



(He Ne) + + e 



(He Ar) + + e" 



-> He' + Ne'(2s), 



-+ He' + Ar' (3d', 3d") 



(15) 



(16) 



are responsible for selective excitation and oscillation in pulsed He-Ne and He-Ar lasers. 120 Metastable 
He 2 3 Si-atoms are essential for the formation of the molecular ions (He Ne) + and (He Ar) + . 

Molecular Photodissociation 

Broad molecular absorption-bands enable large amounts of optical power to be coupled into a gas. 
The resulting fluorescence from the dissociated atoms has narrow line-width characteristics of atomic 
spontaneous emission. As in dissociative excitation-transfer, photodissociation of a diatomic molecule 
in general gives one atom in an excited state and one in the ground-state, via 

AB + hv ► A' + B -t- kinetic energy. (17) 

Photon energies in excess of 3 eV are required to supply the photodissociation energy of AB and the 
excitation and kinetic energies of A' and B. 



230 



Handbook of Lasers 



In the iodine laser, photodissociation occurs during flash photolysis in the reaction 

CX 3 l + hv > l'( 2 P° l/2 ) + CX 3 



(18) 



(where X = H or F) to give mainly selective excitation of the first excited ( 2 P, /2 ) state of atomic iodine, 
and 



I'( 2 Pi/ 2 ) 



- im l2 ) + hv 



(19) 



with^ = 1.315 microns. 70 " 72 



CHARACTERISTICS OF IMPORTANT NEUTRAL GAS LASERS 

The 0.6328-/im Helium-Neon Laser 

The output power of the 0.6328-/mi He-Ne laser is a function of a number of discharge parameters. 
These include: gas pressure, tube diameter (bore), mixture ratio, current (electron density) and gas 
temperature. For maximum output power at 0.6328 /mi, the (superradiant) 3s 2 - 3p 4 transition at 3.39 
/xm must be suppressed by the use of wavelength selection, selective cavity-mirror reflectivities or in- 
homogenous longitudinal magnetic fields. 

Figures 6-33, 6-34, and 6-35 show the effect of total pressure, mixture ratio and tube diameter on 
the output power realizable at 0.6328 /mi with oscillation eliminated on the competing 3.39-//m line. 102 
Cavity and mirror data applicable to the results given in the figures for a spherical-mirror and high- 
reflectivity prism-cavity configuration are given in Table 6-10. 

The relationship between output power, gain, cavity loss, optimum mirror transmission and cavity 
configuration can be determined from "The output power of a 6328-A He-Ne gas laser," and "On the 
optimum geometry of a 6328-A laser oscillator," by P. W. Smith. 1 06 ' 107 

The results given in Figures 6-33, 6-34 and 6-35 are summarized in Figure 6-36, in which the total 
pressure and tube diameter product is plotted versus capillary (tube) diameter for various He-Ne 
pressure ratios at each diameter. Under optimum conditions pD = 3.6 Torr-mm, 94 ' 107 in close agree- 
ment with that stated by P. W. Smith 106 to be optimum for output at 0.6328 /mi. Figure 6-37 shows the 
optimum He : Ne pressure ratio versus tube diameter. It should be noted that Figures 6-33 to 6-37 are 
related to He-Ne mixtures in which the helium is 4 He. A 25 percent increase in power can be achieved by 
substituting isotopic 3 He for 4 He. 

Values of optimum current (for oscillation at 0.6328 /mi) versus discharge tube diameter are plotted 
in Figure 6-38. This figure is a modification of that given by Field. 102 Curve B exhibits the constancy of 



I.I 

1.0 

^ 0.9 

"E 0.8 
o 
^ 0.7 

J. 0.6 

5 0.5 

^ 0.4 

o 0.3 

Q. 

0.2 
0.1 



- 2.0 




12 3 

TOTAL PRESSURE (Torr) 

Fig. 6-33. Output power and normalized output power vs. total pressure for a discharge tube diameter (d) of 1 5 mm 
and a plasma length {£) of 12.5 cm. (From [102] by permission of the American Institute of Physics.) 



CM 

E 
u 

I 

"O 



O 
0. 



6 Neutral Gas Lasers 
28 

24 
20 



231 



1. 6 




He:Ne 


= 5U 7:1 










1. 4 


- 




(/ \Wi 










1. 2 






™/^\^S 








- 


I.O 






f \ l 0: ^x 








- 


0.8 














_ 


0.6 
















0.4 
















0.2 














•^^ - 






l 


I 1 1 


« 


• 


» • 


• 



e£ 



E 

O 

2 a. 



2 3 4 

TOTAL PRESSURE (Torr) 



Fig. 6-34. Output power and normalized output power vs. total pressure for a discharge tube diameter (d) of 3.0 mm, 
and a plasma length (0 of 55 cm. (From [102] by permission of the American Institute of Physics.) 



0.9 
0.8 
0.7 



(M 



0.6 

1 0.5 

■o 

*> 0.4 



§ 03 



0.2 
0.1 



- 


/xHe:Ne=5:l 








- 


- 1 




C 3 ' 1 






; 


- / 






/^ 7:| 




- 










^10:1 


- 


- 


1 1 1 


1 I 


1 


T" 1 


- 



28 
24 
20 



16 S 

12 I 

a. 



12 3 4 5 

TOTAL PRESSURE (Torr) 

Fig. 6-35. Output power and normalized output power vs. total pressure for a discharge tube diameter (d) of 5.0 mm 
and plasma length (0 of 65 cm. (From [102] by permission of the American Institute of Physics.) 

current density under optimum discharge conditions found to apply to the 0.6328-^m He-Ne laser when 
oscillation at 3.39 /^m is suppressed. Curve A (an addition to the figure given by Field) is a plot of the 
relationship 



L 



„(mA) = 3.5 + 1.5 D 2 



(20) 



between optimum current for oscillation at 0.6328 jrni and tube diameter, where D is in mm, when os- 
cillation at 3.39 urn is not suppressed. 196 

Under optimum discharge conditions and where the pD is maintained constant, the saturated gain 
(G s ) exhibits a 1/D dependence. This is due to the way in which the population of the upper laser level 



232 Handbook of Lasers 

follows the concentration of He 2% metastables in the discharge, the concentration of which is pro- 
portional to the pressure (p), or inversely proportional to D. 94159 

In a 5 : 1 He-Ne mixture without suppression of the 3.39-jum line, with an optimum discharge 
current given by Eq. (20) 

G s = 3.0 x 10~ 2 <f/D percent, (21) 

TABLE 6-10. 0.6328-nm CAVITY AND 
MIRROR DATA 



Tube i.d. (d) 
(mm) 



1.5 
3.0 
5.0 
8.0 



Mirror Radius 
(m) 



0.5 

2 

2 

10 



Mirror 


Cavity 


Transmission 


Length (O 


(%) 


(cm) 


1.1 


22 


1.0 


70 


1.0 


80 


1.1 


215 




2 3 4 5 6 7 

CAPILLARY DIAMETER (mm) 

Fig. 6-36. Optimum total pressure x tube diameter (Torr-mm) vs. capillary diameter (mm) for various He:Ne 
mixture-ratios. The dashed line at a pD of 3.6 Torr-mm represents experimentally observed optimum conditions to give 
maximum output power at 0.6328 /xm. (From [102] by permission of the American Institute of Physics.) 




2 3 4 5 6 7 8 

CAPILLARY DIAMETER (mm) 

Fig. 6-37. Optimum He : Ne ratio as a function of capillary diameter. (From [102] by permission of the American 
Institute of Physics.) 



6 Neutral Gas Lasers 



233 



IbU 






< 






j§ 140 






z 






UJ 






£ 120 






r> 






o 






W ioo 












cr 






< 






5 80 






<n 






Q 






5 60 






3 






2 




5.1 y/ 


H 40 


. 


•/ 


0. 






O 


He:Ne 


/l\ 


20 


■ 7:1 > 






2 3 4 5 6 7 8 
DISCHARGE TUBE DIAMETER (mm) 

Fig. 6-38. Optimum discharge current as a function of capillary diameter. B is the observed linear relationship 
between optimum discharge and capillary diameter when oscillation at 3.39 fim is suppressed (after (102)). Curve A is a 
curve of the same relationship, when oscillation at 3.39 /urn is not suppressed (Eq. (20), [196]). 

where / is the plasma length in cm and D is the tube diameter in cm. 150 The single-pass gain (G ) obtain- 
able on the Ne 3s 2 - 2p 4 transition at 0.6328 \im has a more complicated dependence on discharge con- 
ditions than Eq. (21). 108 

The effect of the competing Ne 3s 2 - 3p 4 transition at 3.39 /zm on oscillation at 0.6328 ^m is reduced 
by Zeeman splitting the 3.39-/xm line by means of a longitudinal magnetic field over the active length of 
the discharge. 105,109 The variation of output power at 0.6328 /mi and 3.39 (im versus magnetic field is 
given in Figure 6-39. An approximate 50 percent increase in power at 0.6328 fim over that given in 
Figures 6-33 to 6-35 can be achieved, if a weak inhomogenous magnetic field is used in conjunction with 
prism wavelength selection. 102 

The output power at 0.6328 pm is also affected by the gas temperature in the active region of the 
plasma. 104,110 This is shown in Figure 6-40. The variation of output-power with discharge-tube 
wall-temperature, reflects the effect of the gas temperature on numerous collisional and diffusive effects 
in the He-Ne laser. 




3 
I- 
O 



90 180 270 

MAGNETIC FIELD (GAUSS) 



360 



Fig. 6-39. Competition of emission at 3.39 /xm (curves 1 and 2) and 0.6328 fxm (curves 3 and 4) with the plasma in a 
longitudinal magnetic field. Curves 1 and 3, and 2 and 4 were recorded simultaneously. The rf-drive power for 1 and 3 
was greater than for 2 and 4. Excitation conditions: rf-excitation, He : Ne ratio 7:1, total pressure 0.8 Torr, tube diameter 
4 mm. (From Alekseeva and Gordeev [105] by courtesy of the Optical Society of America.) 



234 Handbook of Lasers 

100 r- 




1.0 1.5 2.0 2.5 3.0 

DENSITY OF Ne ATOMS (I0 l5 cm" 3 ) 

Fig. 6-40. Output power of a 0.6328-/xm He-Ne laser as a function of atom density in He : Ne mixture for various 
wall temperatures of the discharge tube. Curve 1-293 K; 2-425 K; 3-483 K; 4-640 K and 5-780 K. Excitation 
conditions: dc-discharge current 70 mA, He : Ne ratio 8 : 1, D = 8 mm. (From Gonchukov et al. [104] by courtesy of the 
Optical Society of America.) 

The 3.5- jum and 2.02 /*m Xe and Xe-He Lasers 

A number of 5d — 6p transitions in neutral xenon exhibit high gain. Two of them, the 5d[7/2]3 — 
6p[3/2], transition at 3.507 /mi and the 5d[3/2]i - 6p[3/2], transition at 2.026 /mi exhibit extremely high 
gain. They are of technological interest, because they provide useful coherent sources in the infra-red 
with the additional attraction that their wavelengths are situated in atmospheric windows. Although of 
high gain, they have low-power capabilities of less than a mW. 177 ' 183 

The atomic processes that lead to high gain involve direct electron-impact excitation from the 
ground state in both pure Xe and Xe-He laser mixtures. Figure 6-41 shows that in the Xe-He laser, 
energy coincidences do not exist between the lowest (He 2 3 S]) helium metastable and neutral energy 
levels of xenon, so that direct excitation-transfer from helium does not occur. It is possible that in a 
Xe-He discharge, helium metastables are involved in some indirect process that populates the 5d-states 
as well as in the Penning reaction 



He* 2 3 S, + Xe 
(HeXe) + 



-+ (HeXe) + + e~, 
-+ He + Xe + , 



(22a) 
(22b) 



which increases the electron concentration without an apparent decrease in electron temperature re- 
sulting from the addition of large quantities ( ~ 10-40 Torr-mm) of helium. 

Population inversion occurs readily between the 5d and 6p levels because of favorable lifetimes of 
the levels. The lifetimes of the upper states are approximately thirty times longer than those of the 6p 
states, so that given equal excitation of both states, population inversion is easily achieved in a dis- 
charge. 175 - 201 

Optical gains of about 10 5 per meter are obtainable on the 3.5-/mi line in a discharge in a 7-mm bore 
tube in pure Xe, or 10 6 per meter in a Xe-He mixture. 181,182 On the 2.026-/mi line optical gains in excess 
of 2 x 10 2 per meter (in a Xe-He mixture in an rf-excited discharge in a 7-mm bore tube) have been 
reported. 171 In the case of the 2.026-/mi line, helium appears to be essential in producing high gain. 178 ' 197 
This would indicate that helium plays a more active role than just increasing the electron concentration 
and the extent of the direct electron-impact excitation. 

The dependence of output power on the discharge current and pressure for a dc-excited laser in 
pure xenon operating at 3.5 /mi is presented in Figure 6-42. A curve of output power at 3.5 //m versus 



6 Neutral Gas Lasers 



235 



HELIUM 

2 3 S| 20 r 
19 
18 

% I2p 



XENON 



g ■ I h 7, 



UJ 



8 - 



S 



Xe 



— , ^ . 5d 
7s 6p = 



6s 



6s 




5d[3/2J -6p[3/2J AT2.026Mm 



5d[7/2] -6p[5/2] AT 3.508 /im 



He (2 , S n ) 



Xe (5p 6 ) 



Fig. 6-41. Partial energy-level diagram of xenon and of helium, showing disposition of the two 
superradiant 5d-6p laser transitions at 3.5 jxm and 2.026 jam and the He 2 3 Si metastable state. 




60 80 100 120 140 
DISCHARGE CURRENT (mA) 



90 



Fig. 6-42. 3.5-ju.m output power versus discharge current and gas pressure of a pure- 
xenon laser, D = 6 mm. (Ref. 180) 



236 Handbook of Lasers 

1.0 r 



0.8 
uj 
§0.6 



2o.4 

I- 
z> 
o 

0.2 



0.5 1.0 1.5 

TOTAL PRESSURE 



2.0 
(Torr) 



2.5 



3.0 



Fig. 6-43. 3.5-fim laser output power versus total pressure of a 200 : 1 , He : Xe gas mixture. The output power is 
related to the maximum power at 2.5 Torr. Excitation conditions: 30 MHz rf-excitation at approximately 100 W, 
D = 12 mm. (From Kuznetsov and Mash [174] by courtesy of the Scripta Press.) 

total (He-Xe) pressure using rf-excitation is given in Figure 6-43. Strong cataphoretic effects in a dc- 
excited Xe-He laser make it imperative to use rf-excitation. Rapid gas clean-up in discharges in both pure 
Xe and He-Xe mixtures make it essential to use some form of pressure control. 180 

Representative discharge conditions for the two high-gain 3.5-/mi and 2.026-//m Xe lines are 
tabulated below. 

TABLE 6-11. XENON-LASER DISCHARGE 
CONDITIONS 



Line 



pD 

(Torr-mm) 



Mixture Ratio 
He : Xe 



Excitation References 



3.507 


<0.03 


pure Xe 


d.c. 


180, 181 




<30 


200:1 


r.f 


174 




< 13 


60:1 


r.f 


181 


2.026 


~ 15 


100:1 


r.f 


171 




~20 


500:1 


r.f 


178 




~35 


25:1 


r.f 


173 



In the 3.5-/mi pure-xenon laser there is no optimum gas pressure in the range 10-150 mTorr. The 
optical gain increases monotonically as the pressure decreases. The observed dependence between xenon- 
pressure and tube-diameter is of the form 

pD" = a constant(C) (23) 

where n ^ 3.2 + 0.2, and C depends on the gain. 177,183 

For large-diameter tubes (i.d. > 7 mm.) the gain is proportional to 1/D. For i.d. < 3 mm, the gain 
varies as (D)~ n , where n > 1 for pressures of xenon, p > 50 mTorr, and n < 1 for p < 50 mTorr. 

In the Xe-He 2.026-//m laser for tube-diameters between 3 and 5 mm the gain is approximately 
proportional to 1/D. 171 

Other lines at 5.5754 /mi and 3.8697 /mi, on the basis of upper- to lower-state lifetime-ratios and 
relative transition probabilities, 177 > 201 are likely to exhibit optical gain as high as that realizable on the 
3.5-/mi and 2.02-/im lines. ' 78 



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6 Neutral Gas Lasers 237 

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6 Neutral Gas Lasers 239 

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106 P W. Smith, "The output power of a 6328-A He-Ne gas laser," IEEE J. Quant. Electronics, QE-2, 62-68, 1966. 

107 P W. Smith, "On the optimum geometry of a 6328 A laser oscillator," IEEE J. Quant. Electronics, QE-2, 77-79, J 966 - 

108 G. Herziger, W. Holzapfel and W. Seelig, " Verstarkung einer He-Ne-gasentladung fur die laser wellenlange," A =6328 
AE," Z. fur Physik, 189, 385-400, 1966. ,„,,„,«, o*,i 

109 W E Bell and A. L. Bloom, "Zeeman effect at 3.39 microns in a helium-neon laser, Appl. Optics, 3, 4U-413, iyb4. 

110 1. M. Belusova, O. B. Danilov, 1. A. Elkina and K. M. Kiselev, "Investigation of the causes of gas temperature effects on the 
generation of power of a He-Ne laser at 6328 A," Opt. Spectry., 16, 44-41, 1969. 

111. L. Allen and D. G. C. Jones, "Principles of Gas Lasers," Plenum Press, New York, and Butterworths, London, 1967, pp. 
' 73-103. 

112. A. L. Bloom, "Gas Lasers," John Wiley, Inc., New York, 1968, pp. 52-59. 

113 A. D. White, "Anomalous behaviour of the 6402. 84-A gas laser," Proc. IEEE., 52, 721, 1964. 

114. A. L. Bloom and D. L. Hardwick, "Operation of He-Ne lasers in the forbidden resonator region," Phys. Lett., 20, 373- 

115. R. N. Zitter, "2s-2p and 3p-3s neon transitions in a very long laser," Bull. Am. Phys. Soc, 9, 500, 1964. 

116 R N. Zitter, "2s-2p and 3p-2s transitions of neon in a laser ten meters long," J. Appl. Phys., 35, 3070-3071, 1964. 

117 V P. Chebotayev and L. S. Vasilenko, "Investigation of a neon-hydrogen laser at large discharge currents," Sov. Phys.- 

' JETP, 21, 515-516, 1965. ... . . UJ • ♦ ■ u u 

118 V L Afanas'eva, A. V. Lukin and K. S. Mustafin, "Electron energy distribution in a neon-hydrogen mixture in a hollow- 
' cathode discharge," Sov. Phys.-Tech. Phys., 12, 233-235, 1967. ( ,„«,<, 

119. R. M. McClure, R. Pizzo, M. Schiff and C. B. Zarowin, "Laser oscillation at 1.06 microns in He-Ne, Proc. Ihth, 5J, 
851, 1964. J L ,. 

120 E 1. Shtyrkov and E. V. Subbes, "Characteristics of pulsed laser action in helium-neon and helium-argon mixtures, 
' Opt. Spectry., 21, 143-144, 1966. 

121 I Itzkan and G. Pincus, "1.0621-/1 He-Ne gas laser," Appl. Optics., 5, 349, 1966. 

122 R A. McFarlane, C. K. N. Patel, W. R. Bennett, Jr. and W. L. Faust, "New helium-neon optical maser transitions, 
Proc. IRE., 50, 2111-2112, 1962. 

123 V P Chebotayev and V. V. Pokasov, "Operation of a laser on a mixture of He-Ne with discharge in a hollow cathode, 
' Radio Ena. Electr. Phys., 10, 817-819, 1965. 

124. C. G. Petrash and I. N. Knyazev, " Study of pulsed laser generation in neon and mixtures of neon and helium, Sov. Phys. 
' JETP, 18, 571-575, 1964. , 

125. R. der Agobian, J. L. Otto, R. Cagnard and R. Echard, "Cascades de transitions stimulees dans le neon pur, Compt. 
Rend., 259, 323-326, 1964. 

126. O. Andrade, M. Gallardo and K. Bockasten, " High-gain laser lines in noble gases," Appl. Phys. Lett., 11, 99-100, 1967. 

127. V. P. Chebotayev, " Effect of hydrogen and oxygen on the operation of a neon maser," Radio Eng. Electr. Phys., 10, 316- 
318, 1965. . . 

128. A. Javan, W. R. Bennett, Jr. and D. R. Herriott, "Population inversion and continuous optical maser oscillation in a gas 
discharge containing a He-Ne mixture," Phys. Rev. Lett., 6, 106-110, 1961. 

129 R der Agobian, R. Cagnard, E. Echard and J. L. Otto, " Nouvelle cascade de transitions stimulee du neon, Compt. 

' Rend. 258, 3661-3663, 1964. 

130. W. R. Bennett, Jr. and J. W. Knutson, Jr., "Simultaneous laser oscillation on the neon doublet at 1.1523 p., Proc. ILLL., 
' 52, 861-862, 1964. 

131. C. K. N. Patel, "Optical power output in He-Ne and pure Ne maser," J. Appl. Phys., 33, 3194-3195, 1962. 

132! V. P. Chebotayev, "Operating condition of an optical maser containing a helium-neon mixture," Radio Eng. Electr. Phys., 
' 10, 314-316, 1965. „ 

133. H. A. H. Boot, D. M. Clunie and R. S. A. Thorn, " Pulsed laser operation in a high-pressure helium-neon mixture, Nature, 
198, 773-774, 1963. , 

134. J. Smith, "Optical maser action in the negative glow region of a cold cathode glow discharge, ' J. Appl. Phys., 35, 123- 

724, 1964. . . . . . . „ 

135 R der Agobian, J. L. Otto, E. Echard and R. Cagnard, " Emission stimulee de nouvelles transitions infrarouges du neon, 
' Compt. Rend., 257, 3344-3847, 1963. . . . 

136. V. N. Lisitsyn, A. 1. Fedchenko and V. P. Chebotayev, "Generation due to upper neon transitions in a He-Ne discharge 

optically pumped by a helium lamp," Opt. Spectry., 27, 157-161, 1969. 

137 E. J. Blau, B. F. Hochheimer, J. T Massey and A. G. Schulz, "Identification of lasing energy levels by spectroscopic 
' techniques'," J. Appl. Phys., 34, 703, 1963. , „ 

138 F Gires, H. Mayer and M. Pailette, "Sur quelques transitions presentant l'effet laser dans le melange helium-neon, 
' Compt. Rend., 256, 3438-3439, 1963. . 

139. R. A. McFarlane, W. L. Faust, C. K. N. Patel, "Oscillation of f-d transitions in neon in a gas optical maser, Proc. ILLt., 
' 51, 468, 1963. . , 

140. V. N. Lisitsyn and V. P. Chebotayev, "The generation of laser action in the 4f-3d transitions of neon by optical pumping 
of a He-Ne discharge with helium lamp," Opt. Spectry., 20, 603-604, 1966. 

141 R A. McFarlane, W. L. Faust, C. K. N. Patel and C. G. B. Garrett, Gas maser operation at wavelengths out to 28 microns 
in "Quantum Electronics 111," P. Grivet and N. Bloembergen, eds., Columbia University Press, 1964, pp. 573-586. 

142 D Rosenberger, "Oscillation of three 3p-2s transitions in a He-Ne laser," Phys. Lett., 9, 29-31, 1964. 

143. W. R. Bennett, Jr., A. T. Pawilkowski, "Additional cascade laser transitions in He-Ne mixtures," Ball. Am. Phys. Soc, 

9, 500, 1964. 
144 V N Smiley, "New He-Ne and Ne laser lines in the infra-red," Appl. Phys. Lett., 4, 123-124, 1964. 

145* W. L. Faust, R. A. McFarlane, C. K. N. Patel and C. G. B. Garrett, " Noble gas optical maser lines at wavelengths between 
2 and 35 /x," Phys. Rev., 133, A1476-A1478, 1964. 

146. J. L. Otto, R. Cagnard, R. Echard and R. der Agobian, " Emission stimulee de nouvelles transition infrarouges dans les 
' gaz rares," Compt. Rend., 258, 2779-2780, 1964. , „ 

147. R. Grudzinski, M. R. Pailette and J. Becrelle, "Etude des transitions laser complees dans un melange helium-neon, 
' Co mpt. Rend., 255, 1452-1454, 1964. 

148. K. Bergman and W. Demtroder, "A new cascade laser transition in He-Ne mixture, Phys. Lett., J9A, y4-y:>, WW. 



240 Handbook of Lasers 

149. H. J. Gerritsen and P. V. Goedertier, "A gaseous (He-Ne) cascade laser," Appl. Phys. Lett., 4, 20-21, 1964. 

150. V. N. Smiley, "A long gas phase optical maser cell" in "Quantum Electronics III," P. Grivet and N. Bloembergen, eds., 
Columbia University Press, New York, pp. 587-591, 1964. 

151. P. G. McMullin, "Precise wavelength measurement of infrared optical maser lines," Appl. Optics, 3, 641-642, 1964. 

152. C. K. N. Patel, R. A. McFarlane and W. L. Faust, "Further infrared spectroscopy using stimulated emission techniques" 
in "Quantum Electronics III," P. Grivet and N. Bloembergen, eds., Columbia University Press, New York, 1964, pp. 
561—572. 

153. H. Brunet and P. Laures, "New infrared gas laser transitions by removal of dominance," Phys. Lett., 12, 106-107, 1964. 

154. A. L. Bloom, W. E. Bell and R. C. Rempel, "Laser action at 3.39 a in a helium-neon mixture," Appl. Optics, 2 317-318 
1963. 

155. R. A. McFarlane, W. L. Faust, C. K. N. Patel and C. G. B. Garrett, " Neon gas maser lines at 68.329u and 85.047 u " 
Proc. IEEE., 52, 318, 1964. ^' 

156. C. K. N. Patel, R. A. McFarlane, and C. G. B. Garrett, " Laser action up to 57.355 a in gaseous discharges (Ne He-Ne) " 
Appl. Phys. Lett., 4, 18-19, 1964. 

157. C. K. N. Patel, R. A. McFarlane and C. G. B. Garrett, " Optical-maser action up to 57.355 um in neon," Bull. Am Phvs 
Soc, 9, 65, 1964. 

158. C. K. N. Patel, W. L. Faust, R. A. McFarlane and C. G. B. Garrett, "CW optical-maser action up to 133 u (0.133 mm) 
in neon discharges," Proc. IEEE, 52, 713, 1964. 

159. E. F. Labuda, Ph.D. Dissertation, Polytechnic Institute of Brooklyn, New York, 1967. 

160. W. T. Silfvast, " Efficient CW. laser oscillation at 4415 A in Cd (II)," Appl. Phys. Lett., 13, 169-171, 1968. 

161. W. T. Silfvast, " New cw metal-vapor laser transitions in Cd, Sn and Zn," Appl. Phys. Lett., 15, 23-25, 1969. 

162. J. P. Goldsborough, "Stable long life cw excitation of helium-cadmium lasers by dc cataphoresis." Appl. Phvs Lett 15 
159-161, 1969. ' '' ' 

163. D. C. Sinclair, "Near-infrared oscillations in pulsed noble-gas-ion lasers," /. Opt. Soc. Am., 55, 571, 1965. 

164. K. Bockasten, T. Lundholm and O. Andrade, " New near infrared laser lines in argon I," Phys. Lett., 22, 145-146, 1966. 

165. A. D. Brisbane, "High gain pulsed laser," Nature, 214, 75, 1967. 

166. K. Bockasten and O. Andrade, "Identification of high gain laser lines in argon," Nature, 215, 382, 1967. 

167. F. A. Horrigan, S. H. Koozekanani and R. A. Paananen, "Infrared laser action and lifetimes in argon II " AddI Phvs 
Lett., 6, 41-43, 1965. 

168. P. K. Cheo and H. G. Cooper, " Ultraviolet ion laser transitions between 2300 A and 4000 A," J. Appl. Phvs. 36 1862- 
1865, 1965. 

169. W. T. Walter and J. M. Jarrett, "Strong 3.27-fx oscillation in xenon," Appl. Optics, 3, 780-790, 1964. 

170. G. E. Courville, P. J. Walsh and J. H. Wasko, " Laser action in Xe in two distinct current regions of ac and dc discharges " 
J. Appl. Phys., 35, 2547-2548, 1964. ' 

171. C. K. N. Patel, W. L. Faust and R. A. McFarlane, "High gain gaseous (Xe-He) optical maser," Appl. Phys. Lett. 1 84- 
85, 1962. 

172. C. K. N. Patel, R. A. McFarlane and W. L. Faust, " High gain medium for gaseous optical masers," in "Quantum Elec- 
tronics III," P. Grivet and N. Bloembergen, eds., Columbia University Press, New York, (1964), pp. 507-514. 

173. W. L. Faust, R. A. McFarlane, C. K. N. Patel and C. G. B. Garrett, "Gas maser spectroscopy in the infrared " Appl. 
Phys. Lett., 1, 85-88, 1962. 

174. A. A. Kuznetsov and D. I. Mash, "Operating conditions of an optical maser with a helium-xenon mixture in the middle 
infrared region of the spectrum," Radio Eng. Electr. Phys., 1C, 319-320, 1965. 

175. V. F. Moskalenko, E. P. Ostapchenko and V. I. Pugnin, "Mechanism of xenon-level population inversion in the positive 
column of a helium-xenon mixture," Opt. Spectry., 23, 94-95, 1967. 

176. V. N. Smiley, A. L. Lewis and D. K. Forbes, "Gain and bandwidth narrowing in a regenerative He-Xe laser amplifier " 
J. Opt. Soc. Amer., 55, 1552-1553, 1965. 

177. P. O. Clark, R. A. Hubach, and J. Y. Wada, "Investigation of the dc-excited xenon laser," Hughes Research Labs Final 
Report J PL Contract N0950803 (1965). 

178. C. S. Willett, T. J. Gleason and J. S. Kruger (unpublished work), 1970. 

179. L. Liberman, "Sur la structure hyperfine de quelques raies laser infrarouges de xenon 129," Comp. Rend., 266, 236-239 
1968. 

180. D. R. Armstrong, "A method for the control of gas pressure in the xenon laser," IEEE J. Quant. Electronics OE-4 968- 
969, 1968. 

181. W. B. Bridges, " High optical gain at 3.5 /x in pure xenon," Appl. Phys. Lett., 3, 45-47, 1963. 

182. R. A. Paananen and D. L. Bobroff, " Very high gain gaseous (Xe-He) optical maser at 3.5 /x," Appl. Phys. Lett., 2, 99-100, 
1963. 

183. P. O. Clark, "Investigation of the operating characteristics of the 3.5 u xenon laser," IEEE J. Quant. Electronics, QE-1 
109-113, 1965. 

184. Yu. N. Petrov and A. M. Prokhorov, "75-micron laser," Sov. Phys.- J ETP Letters, 1, 24-25, 1965. 

185. A. A. Kuznetsov, D. I. Mash, B. M. Milinkis and L. P. Chirina, "Operating conditions of an optical quantum generator 
(laser) in helium-neon and xenon-helium gas mixtures," Rad. Eng. Electr. Phys., 9, 1576, 1964. 

186. I. Tobias and W. M. Strouse, "The anomalous appearance of laser oscillation at 6401 A," Appl. Phvs. Lett. 10 342-344 
1967. 

187. P. K. Cheo and H. G. Cooper, "UV laser transitions from 2400-3700 A in ionized atmospheric and noble gases," Bull. 
Am. Phys. Soc, 9, 626, 1964. 

188. R. A. McFarlane, "Laser oscillation on visible and ultraviolet transitions of singly and multiply ionized oxygen, carbon 
and nitrogen," Appl. Phys. Lett., 5, 91-93, 1964. 

189. W. E. Bell, A. L. Bloom and J. P. Goldsborough, "New laser transitions in antimony and tellurium " IEEE J. Quant. 
Electronics, QE-2, 154, 1966. 

190. D. P. Akitt and C. F. Wittig, " Laser emission in ammonia," J. Appl. Phys., 40, 902-903, 1969. 

191. K. S. Mustafin, V. A. Seleznev and E. I. Shtyrkov, "Stimulated emission in the negative glow region of a glow discharge " 
Opt. Spectry., 21, 429-430, 1966. 

192. R. L. Abrams and G. J. Wolga, " Direct demonstration of the validity of the Wigner spin rule for helium-helium collisions " 
Phys. Rev. Lett., 19, 1411-1414, 1967. 

193. L. A. Schlie and J. T. Verdeyn, " Radial profile of Ne ls 5 atoms in a He-Ne active discharge and their lens effect on lasing 
at 6401 A," IEEE J. Quant. Electronics, QE-5, 21-29, 1969. 

194. M. A. Kovacs and C. J. Ultee, "Visible laser action in fluorine I," Appl. Phys. Lett., 17, 39-40, 1970. 

195. A. A. Isaev and G. G. Petrash, "Pulsed superradiance at the green line of thallium in Tl I vapor," JETP Lett., 7, 156-158, 
(1968). 

196. J. V. Ramsay, and K. Tanaka, "Construction of single-mode dc operated He/Ne lasers," Jap. J. Appl. Phys., 5, 918-923, 
1966. 



6 Neutral Gas Lasers 241 

197. V. N. Smiley (private communication). 

198. H. S. W. Massey and E. H. S. Burhop, in "Electronic and ionic impact phenomena, Clarendon Press, Oxford, 1952. 

199. E. W. McDaniel in "Collision phenomena in ionized gases," John Wiley, Inc., 1964, p. 584. 

200. L. D. Schearer, " Polarization transfer between oriented metastable helium atoms and neon atoms," Phys. Lett., 27 A, 544- 
545, 1968. ' . v _ . „ „ , _ t 

201. L. Allen, D. G. C. Jones and D. G. Schofield, " Radiative lifetimes and collisional cross sections for Xe 1 and 11, J. Upt. 
Soc. Am., 59, 842-847, 1969. 

202. A. von Engel and N. Steenbeck, in "Elektrische Gasentladungen," Band II, Spnnger-Verlag, Berlin, 1932, P-» 5 - 

203. R. T. Young, Jr., "Calculation of average electron energies in He-Ne discharges," /. Appl. Phys., 36, 2324-2325, 1965. 

204. M. A. Pollack (private communication). „ ,__„ 

205. A. B. Dauger and O. M. Stafsudd, "Observation of CW laser action in chlorine, argon and helium gas mixtures, Ihth 
J. Quant. Electronics, QE-6, 572-573, 1970. 

206. H. B. Dorgela, H. Alting and J. Boers, Physic. Haag, 2, 959, 1935. 

207 Added in proof Oscillation has also been observed on the Balmer H-/3 and H-a lines at 0.4861 jim and 0.4340 ^m respec- 
tively in a pulsed neon discharge. (G. J. Dezenberg and C. S. Willett, submitted to IEEE J. Quant. Electronics, April, 1971.) 



Ionized Gas Lasers 

William B. Bridges and Arthur N. Chester 

Hughes Research Laboratories 
Malibu, California 90265 



INTRODUCTION TO THE TABLES 

The tables in this section include all known laser lines originating from transitions between energy 
levels of the ionized states of atoms in gas discharges. Figure 7-1 indicates by the shaded squares on the 
periodic chart those elements that produce ion laser lines. Not surprisingly, the elements are those 
that occur as gases at room temperature or are easily vaporized. Many other elements doubtless would 
exhibit ion laser action if they were studied. 

The tables following Figure 7-1 list the observed wavelengths with identifications and references. 
The tables are arranged in the order in which they occur as columns in the periodic system, reading 
from left to right, and then within each column, in the order of increasing atomic number. An expla- 
nation of the entries and abbreviations used in each column is given below. 

Wavelength 

This column lists the most accurate available wavelength for the given transition, in micrometers. 
In most cases this value of wavelength has been derived from the spontaneous emission spectroscopic 
literature assuming the indicated classification for the line. Wavelengths in square brackets were taken 
from Ref. 23. 

Abbreviations : 

* Strong or characteristic laser line in pure gas 
? Existence of this laser line may be in doubt 

Measured Value 

This column lists the most accurate measured wavelength of the actual laser output, in micro- 
meters, along with an estimated error in the final digits. 

Identification 

This column lists the emission spectrum (II for singly ionized, III for doubly ionized, and so on), 
the upper, and then the lower level of the atomic transition believed to be responsible for the laser 
emission. The level notation follows that of Charlotte Moore, Atomic Energy Levels, N.B.S. Circular 
467, with the core configuration being given in parentheses. Identifications of the observed laser lines 
have generally been made only on the basis of the measured value of wavelength and theoretical 
plausibility. This can be done with a high degree of confidence in the absence of other nearby spectral 
lines. Identifications in square brackets are tentative and were made by the authors of this review. 

Abbreviations : 

? Classification uncertain 
. . . Classification unknown 

References 

The first reference listed is the first report of laser action on that line, although it may not represent 
the most accurate measurement of the laser wavelength. Additional selected references are given. 

242 



7 Ionized Gas Lasers 



243 



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s 



e 



Q 



mm 

' * ' ' ' t .'! t .''t'lf'*t, 



r/Vj '* • ' * . • ' * :' * : 






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' * .'.' * !' * :' * :'.' * ::* ''f*.'*-\ * t'f!'t\{- 



mi 



S£ 






w. 



<§ 



<§ 



* 



S 



<5 



^ 



^ 



^J 



^ 



f.ff. ' f.:'. ' . ':. * :: >: 



1111 

: i,';'f.';i.';'t.';'f. ' • *.', 



* 



k 



§ 



<§ 



^ 



1 



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^5 



K 



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* !; W$ 



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^ 


^ 


25 


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^ 


^ 


^ 


^ 


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•5 


^ 


^ 


$ 


^ 


* 


* 


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* 


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60 

E 



244 Handbook of Lasers 



Abbreviations: 



CW 
A 



See more complete discussion following G 

the table p 

Continuous oscillation reported S 

Laser oscillation observed only in the U 

afterglow of the discharge pulse hfs 

Error in classification or wavelength X 



Gain measured 
Power output reported 
Superradiant operation reported 
Unique or unusual excitation method 
Hyperfine structure investigated 
Accurate wavelength measurement 



TABLE 7. IONIZED GAS LASER TRANSITIONS 



Wavelength, 



Measured 
value, fj.m 



Ion 



Identification 
Upper level— Lower level 



7.1 GROUP II A 



.854 209 
.866 214 



1.033 014 
1.091 797 



.854 180 ±60 
.866 200 ± 60 



1.033 050 ±50 
1.091 750 ±50 



7.2 GROUP IIB 



References 



7.1.1 CALCIUM 

Ca II ( 1 S)4p 2 P 3 ° /2 - ( 1 S)3d 2 D 5/2 

Ca II ( 1 S)4p 2 P 1 ° /2 - ( 1 S)3d 2 D 3/2 

7.1.2 STRONTIUM 

SrII ( 1 S)5p 2 PS /2 -( 1 S)4d 2 D 5/2 

SrII ( 1 S)5p 2 P? /2 -(iS)4d 2 D 3/2 



131-G,P,S 
131-G,P,S 



48-A,G,S 
48-A,G,S 









7.2.1 ZINC 




.491 160 


.491 160 ± ? 


Znll 


( 1 S)4f 2 F? /2 -( 1 S)4d 2 D 3/2 


81; 82; 125 


.492 404 


.492 500 ± ? 


Znll 


CS)4f 2 F? /2 -eS)4d 2 D 5/2 


56; 14-CW; 84-CW,P; 


*.589 442 


.589 400 ± ? 


Znll 


4s 22 D 3/2 -eS)4p 2 P? /2 


125 
82-CW.P 


.610 253 


.610 280 ± 70 


Znll 


( 1 S)5d 2 D 5/2 - ( 1 S)5p 2 Pg /2 


115; 125 


*.747 879 


.747 830 ± 160 


Znll 


4s 2 2 D 5/2 - eS)4p 2 P^ 2 


115;82-CW,P; 
117-CW,G 


.758 848 


.758 750 ±160 


Znll 


( 1 S)5p 2 P§ /2 -eS)5s 2 S 1/2 


115; 82-CW.P; 
84-CW; 117-CW 


.761 290 


.761 118 ±160 


Znll 


( 1 S)6s 2 S 1/2 - ( 1 S)5p 2 P? /2 


115 


.775 786 


.775 700 ± ? 


Znll 


eS)6s 2 S 1/2 - ( 1 S)5p 2 P? /2 


56-E 






7.2.2 CADMIUM 




*.325 031 


.325 000 ± ? 


Cdll 


5s 22 D 3/2 -eS)5p 2 P? /2 


64-CW.P; 117-CW, 
G,P; 138-P 


*.441 563 


.441 560 ±70 


Cdll 


5s 22 D 5/2 -CS)5p 2 P5 /2 


115; 58-CW,P; 
116-CW,G,P; 125; 
138-P 


.488 172 


.488 200 ± ? 


Cdll 


( 3 D)5p*FS /2 -CS)5d 2 D 3/2 


14-CW 


.502 548 


.502 590 ± ? 


Cdll 


( 3 D)5p 4 F 7 ° /2 -( 1 S)5d 2 D 5/2 


14-CW,P 


*.533 749 


.533 700 ± ? 


Cdll 


eS)4f 2 F 5 ° /2 -eS)5d 2 D 3/2 


56; 84-CW.P; 
1 14-CW; 125 


.537 804 


.537 800 ± ? 


Cdll 


( 1 S)4f 2 F? /2 -( 1 S)5d 2 D s/2 


56; 84-CW.P; 
1 14-CW; 125 


.635 480 


.635 480 ± ? 


Cdll 


( 1 S)6g 2 G 7/2 -( 1 S)4f 2 F§ /2 


114-CW; 127 


.636 004 


.636 010 ± ? 


Cdll 


( 1 S)6g 2 G 9/2 -( 1 S)4f 2 F? /2 


114-CW.P; 126; 127 


.723 689 


.723 690 ± ? 


Cdll 


( 1 S)6f 2 F 5 ° /2 -( 1 S)6d 2 D 3/2 


114-CW; 126; 127 


.728 423 


.728 430 ± ? 


Cdll 


( 1 S)6f 2 F? /2 -( 1 S)6d 2 D 5/2 


114-CW; 126; 127 


.806 687 


.806 690 ± ? 


Cdll 


( 1 S)6p 2 P 3 ° /2 -( 1 S)6s 2 S 1/2 


84-CW,P 


.839 002 


.839 000 ± ? 


Cdll? 


?[( 1 S)llp 2 P? /2 -( 1 S)8s 2 S 1/2 ] 


130 


1.186 36 


1.186 900 ± ? 


Cdll? 


?[( 1 S)10d 2 D 3/2 - ( 3 D)5p 2 D 5 ° /2 ] 


130 



7 Ionized Gas Lasers 245 
TABLE 7. IONIZED GAS LASER TRANSITIONS (Continued) 



Wavelength, 


Measured 


Ion 


Identification 


References 


fim 


value, fim 


Upper level — Lower level 










7.2.3 MERCURY 




.479 701 


.479 700 ± 10 


HgUI 


5d 8 6s 2 (J = 4) - 5d 9 ( 2 D 5/2 )6pi /2 (J = 3) 


61-G.P; 62-A 


*.567 73 


.567 800 ± ? 


Hgll 


( 1 S)5f 2 F? /2 - ( 1 S)6d 2 D 5/2 


6-G,P; 7-U 


*.614 947 


.615 000 ± ? 


Hgll 


( 1 S)7p 2 P 3 ° /2 - ( 1 S)7s 2 S 1/2 


6-G,P; 2; 10-CW; 
32-U,hfs,A; 51; 136; 
144-CW 


.734 66 


.734 600 ± ? 


Hgll 


( 1 S)7d 2 D 5/2 -( 1 S)7p 2 P^ /2 


6 


.741 81 


.741 810 ± ? 


Hgll 


2 P| /2 (109189)-( 1 S)7s 2 S 1/2 


66-G.U 


*.794 47 


.794 500 ± ? 


Hgll 


eS)7p 2 P? /2 -( 1 S)7s 2 S 1/2 


32-U; 2; 136; 144-CW 


.854 98 


.854 700 ± ? 


Hgll 


( 1 S)5g 2 G 7/2 - 2 F£ /2 (121960) 


13 


.862 20 


.862 800 ± ? 


Hgll? 


?( 1 S)8p 2 P| /2 - H6200 (J = 5/2) 


13 


.867 7 


.867 700 ± ? 


Hgll? 




13 


.939 68 


.939 600 ± ? 


Hgll 


( 1 S)10s 2 S 1/2 - ( 1 S)8p 2 PS /2 


13 


1.058 3 


1.058 600 ± ? 


Hgll 


( 1 S)8s 2 S 1/2 - ( 1 S)7p 2 P§ /2 


6; 13 


1.117 686 


1.117 682 ±10 


Hgl 


(not an ion line) 


13-E; 18-A 


1.254 5 


1.254 500 ± ? 


Hgll? 




13 


1.298 1 


1.298 100 ± ? 


Hgll? 




13 


1.365 5 


1.365 500 ± ? 


Hgll? 




13 


1.555 4 


1.555 000 ± ? 


Hgll 


( 1 S)7p 2 P^ / 2-( 1 S)6d 2 D 5/2 


13 


7.3 GROUP HI A 








7.3.1 BORON 




.345 134 


.345 132 ± ? 


BII 


2p 2 *D 2 - ( 2 S)2p 1 P? 
7.3.2 INDIUM 


42 


.468 082 


.468 050 ± 70 


In II 


( 2 S)4f 3 F2 - ( 2 S)5d 3 D 3 


115 


7 A GROUP IV A 








7.4.1 CARBON 




.464 745 


.464 740 ± 04 


cm 


( 2 S)3p 3 P$ - ( 2 S)3s 3 S! 


101 ; 22-A; 60 


.465 016 


.465 021 ± 04 


cm 


( 2 S)3p 3 P? - ( 2 S)3s 3 S! 
7.4.2 SILICON 


101; 3-A; 60 


.408 889 


.408 890 ±10 


Si IV 


4p 2 P 3 3 /2 - 4s 2 S 1/2 


22-E; Note 1 


.455 262 


.455 259 ± 06 


Si III 


( 2 S)4p 3 P5 - ( 2 S)4s 3 Si 


36-E; 111 


.456 782 


.456 784 ± 06 


Si III 


( 2 S)4p 3 P? - ( 2 S)4s 3 S! 


36-E; 111 


.634 710 


.634 724 ± 06 


Sill 


( 1 S)4p 2 PI /2 -( 1 S)4s 2 S 1/2 


36-E; 33-A; 111 


.637 136 


.637 148 ±06 


Sill 


( 1 S)4p 2 P? /2 - ( x S)4s 2 S 1/2 


36-E; 111 


.667 188 


.667 193 ±06 


Sill 


( 3 P°)4p 4 D 7/2 - ( 3 P°)4s 4 P? /2 
7.4.3 GERMANIUM 


36-E; 111 


.513 175 


.513 150 ±70 


Gell 


( 1 S)4f 2 F 5 ° /2 -( 1 S)4d 2 D 3/2 


115 


.517 865 


.517 840 ±70 


Gell 


( 1 S)4f 2 F? /2 - ( 1 S)4d 2 D s/2 
7.4.4 TIN 


115 


.579 918 


.579 870 ±70 


SnII 


( 1 S)4f 2 F? /2 -( 1 S)5d 2 D 5/2 


115 


.645 350 


.645 300 ±70 


SnII 


( 1 S)6p 2 PS /2 - ( 1 S)6s 2 S 1/2 


115; 117-CW.G 


.657 926 


.657 903 ± 06 


Sn 




42; 34; Note 2 


.684 405 


.684 400 ± 70 


SnII 


( 1 S)6p 2 P 1 ° /2 - ( 1 S)6s 2 S 1/2 


115; 117-CW 



1. Si IV, .408889 /xm: Ref. 22 erroneously lists this line as occurring in a xenon discharge; in fact, it was actually observed 
in an argon discharge. Although a CW argon laser line is listed at 0.40886 /xm, the Si IV line is still believed to be genuine. How- 
ever, see also Ref. 33. 

2. Sn, .657926 /xm: This may be a Sn I line; see Ref. 34. 



246 Handbook of Lasers 

TABLE 7. IONIZED GAS LASER TRANSITIONS {Continued) 



Wavelength, 


Measured 
value, fj,m 


Ion 


Identification 
Upper level — Lower level 


References 








7.4.5 LEAD 




.537 21 


.537 210 ±70 


Pbll 


( x S)5f 2 F? /2 - 6s6p 2 4 P 5/2 


115 


.560 89 


.560 86 ±50 


Pbll 


( 1 S)7p 2 P 3 ° /2 - ( 1 S)7s 2 S 1/2 


120 


.665 99 


.666 01 ± 50 


Pbll 


( 1 S)7p 2 P 1 ° /2 -( 1 S)7s 2 S 1/2 


120 


7.5 GROUP 


VA 














7.5.1 NITROGEN 




.336 734 


.336 732 ±06 


NIII 


( 3 P°)3p 4 P 5/2 -( 3 P°)3s 4 P£ /2 


35 


.347 867 


.347 876 ±05 


NIV 


( 2 S)3p 3 P§ - ( 2 S)3s 3 S 1 


101 


.348 296 


.348 302 ±06 


NIV 


( 2 S)3p 3 P? - ( 2 S)3s 3 S! 


35 


.399 501 


.399 499 ±02 


Nil 


eP^p^ - ( 2 P°)3s 1 P? 


3 


.409 732 


.409 729 ±06 


NIII 


0S)3p 2 P 3 ° /2 -CS)3s 2 S 1/2 


101 


.410 338 


.410 336 ±02 


NIII 


( 1 S)3p 2 P 1 ° /2 - ( 1 S)3s 2 S 1/2 


101 ; 3-A 


.451 088 


.451 045 ±23 


NIII 


( 3 P°)3p*D 5/2 - ( 3 P°)3s 4 P 3 ° /2 


101 


.451 487 


.451 486 ±03 


NIII 


( 3 P )3p*D 7/2 -( 3 P°)3s*P! /2 


101 ; 3-A 


.462 140 


.462 100 ±80 


Nil 


[( 2 P°)3p 3 P - ( 2 P°)3s 3 P?] 


109 


.463 055 


.463 051 ± 02 


Nil 


( 2 P°)3p 3 P 2 - (*P°)3s 3 P2 


101 ; 3-A 


.464 310 


.464 390 ± 80 


Nil 


[( 2 P°)3p 3 P 1 - ( 2 P°)3s 3 P2] 


109 


.566 663 


.566 662 ±03 


Nil 


( 2 P°)3p 3 D 2 - ( 2 P°)3s 3 P? 


103 


.567 601 


.567 603 ± 03 


Nil 


( 2 P°)3p 3 D! - ( 2 P°)3s 3 Pg 


103 


*.567 956 


.567 953 ± 03 


Nil 


( 2 P°)3p 3 D 3 - ( 2 P°)3s 3 P2 


76; 22; 103-A 


.568 622 


.568 690 ±80 


Nil 


[( 2 P°)3p 3 D x -( 2 P°)3s 3 P?] 


109 


.648 207 


.648 260 ± 60 


Nil 


^P^p^ - ^P^s^ 


109 






7.5.2 PHOSPHORUS 




.334 769 


.334 776 ±06 


PIV 


( 2 S)4p 3 P^ - ( 2 S)4s 3 Si 


36 


.422 208 


.422 225 ± 06 


PHI 


( 1 S)4p 2 P 3 ° /2 -( 1 S)4s 2 S 1/2 


36 


*.602 421 


.602 427 ± 06 


PII 


( 2 P°)4p 3 D 2 - ( 2 P°)4s 3 P? 


57; 15-CW,U; 36-A 


.603 421 


.603 419 ± 06 


PII 


(2 P o )4p 3 Di _ (2 P o )4s 3 Po 


36 


*.604 325 


.604 322 ± 06 


PII 


( 2 P°)4p 3 D 3 - ( 2 P°)4s 3 PS 


57; 15-CW,U; 36-A 


.608 786 


.608 804 ±06 


PII 


( 2 P°)4p 3 Di - ( 2 P°)4s 3 P? 


36 


.616 577 


.616 574 ±06 


PII 


( 2 P°)4p 3 D 2 - ( 2 P°)4s 3 P 2 


36 


.784 563 


.784 600 ± ? 


PII 


( 2 P°)4p 1 P 1 - ( 2 P°)4s 1 P? 
7.5.3 ARSENIC 


57 


.549 80 


.549 800 ±100 


As II 


( 2 P )5p 3 D! - ( 2 P°)5s 3 Pg 


8-U 


.555 83 


.555 900 ±100 


As II 


( 2 P°)5p 3 D 2 - ( 2 P°)5s 3 P? 


8-U 


.565 16 


.565 200 ±100 


As II 


( 2 P°)5p 3 D 3 - ( 2 P°)5s 3 P^ 


8-U 


.617 03 


.617 100 ±100 


As II 


( 2 P°)5p 1 P 1 - ( 2 P°)5s 3 PJ 
7.5.4 ANTIMONY 


8-U 


.612 99 


.613 000±100 


Sbll 


( 2 P°)6p 3 D 3 - ( 2 P°)6s 3 P2 
7.5.5 BISMUTH 


9 


.456 084 


.456 070 ± 10 


BiHI 


6s 2 ( 1 S)7p 2 P? /2 - 6s 2 ( 1 S)7s 2 S 1/2 


87-G 


.571 921 


.571 920 ±10 


Bill 


6pi /2 7p 1/2 3 P — 6p 1/2 7s 3 PJ 


87-G 


.759 90 


.759 870 ± 50 


BiHI 


6s 2 ( 1 S)6f 2 F? /2 - 6s 2 ( 1 S)7d 2 D 3/2 


87-G 


.806 89 


.806 920 ± 50 


BiHI 


6s 2 ( 1 S)6f 2 F? /2 - 6s 2 ( 1 S)7d 2 D 5/2 


87-G 



7 Ionized Gas Lasers 
TABLE 7. IONIZED GAS LASER TRANSITIONS (Continued) 



247 



Wavelength, 


Measured 




Identification 


References 


[xm 


value, [im 




Upper level - 


- Lower level 




7.6 GROUP 


VIA 
















7.6.1 OXYGEN 






*.298 378 


.298 386 ±06 


OIII 


^P^p^ - 


- ( 2 P°)3s 1 P? 


22-E; 35 


.304 713 


.304 715 ±06 


OIII 


( 2 P°)3p 3 P 2 - 


( 2 P°)3s 3 P$ 


22-E; 35 


.306 345 


.306 346 ±06 


OIV 


( 1 S)3p 2 P^ /2 - 


-( 1 S)3s 2 S 1/2 


35 






(OIV 


( 3 P°)3p 4 D 3/2 


-( 3 P°)3s 4 P? /2 (.338133) 


\ 


.338 13 


.338 134 ±06 


or 






35 






loiv 


( 3 P°)3p 4 D 5/2 


-( 3 P°)3s 4 P^ /2 (.338128) 


J 


.338 554 


.338 554 ±06 


OIV 


( 3 P°)3p 4 D 7/2 


- ( 3 P°)3s 4 P^2 


35 


.374 949 


.374 947 ± 04 


on 


( 3 P)3p 4 S 3 ° /2 - 


-( 3 P)3s 4 P 5/2 


101 


.375 467 


.375 468 ± 04 


OIII 


( 2 P°)3p 3 D 2 - 


- ( 2 P°)3s 3 P? 


101 


.375 988 


.375 989 ±05 


OIII 


( 2 P°)3p 3 D 3 - 


- ( 2 P°)3s 3 P2 


101 


*.434 738 


.434 738 ± 04 


on 


( 1 D)3p 2 D 3 ° / 2 


- ( 1 D)3s 2 D 3/2 


101 


*.435 128 


.435 123 ±04 


on 


( 1 D)3p 2 D? /2 


-eD)3s 2 D 5/ 2 


101 


*.441 488 


.441 493 ±04 


on 


( 3 P)3p 2 D 5 ° /2 


- ( 3 P)3s 2 P 3/2 


101 


*.441 697 


.441 697 ±04 


on 


( 3 P)3p 2 D 3 ° /2 - 


- ( 3 P)3s 2 P 1/2 


101 


.460 552 


.460 552 ±09 


o 






101 


.464 914 


.464 908 ± 10 


on 


( 3 P)3p 4 D? /2 - 


- ( 3 P)3s 4 P 5/2 


76; 22 


.559 237 


.559 237 ±06 


OIII 


( 2 P°)3p 1 P 1 - 


?Y°M&Y\ 


101 ; 17-P; 22-A 


.664 099 


.664 020 ± 100 


on 


( 3 P)3p 2 S? /2 - 


-( 3 P)3s 2 P 1/2 


17-P 


.672 136 


.672 138 ±04 


on 


( 3 P)3p 2 S? /2 - 
7.6.2 SULFUR 


-( 3 P)3s 2 P 3/2 


101 


.263 898 


.263 898 ±06 


sv 






43 


.332 486 


.332 486 ±06 


SIII 


( 2 P°)4p 3 P 2 - 


( 2 P°)3d 3 PS 


43 


.349 737 


.349 737 ±06 


SIII 






43 


.370 937 


.370 941 ±06 


SIII 


( 2 P°)4p 3 D 2 - 


- ( 2 P°)3d 3 P? 


43 


.492 532 


.492 560 ± 06 


SII 


( 3 P)4p 4 P 3 °/2 - 


-( 3 P)4s 4 P 1/2 


43 


.501 401 


.501 424 ±06 


SII 


( 3 P)4p 2 P 3 ° /2 - 


- ( 3 P)4s 2 P 3/2 


43 


.503 239 


.503 262 ±06 


SII 


( 3 P)4p 4 P 5 ° /2 - 


- ( 3 P)4s 4 P 5/2 


43 


.516 032 


.516 032 ±06 


s 






43 


.521 962 


.521 962 ±06 


s 






43 


*.532 070 


.532 088 ± 06 


SII 


( 1 D)4p 2 F? /2 - 


- ( 1 D)4s 2 D 5/2 


57; 15-CW,U; 43-A 


*.534 567 


.534 583 ± 06 


SII 


( 1 D)4p 2 F§ /2 


- ( 1 D)4s 2 D 3/2 


57; 15-CW,U; 43-A 


.542 864 


.542 874 ±06 


SII 


( 3 P)4p 4 D^ /2 


-( 3 P)4s 4 P 1/2 


57; 43-A 


*.543 277 


.543 287 ±06 


SII 


( 3 P)4p 4 D? /2 


- ( 3 P)4s 4 P 3/2 


57; 15-CW,U;43-A 


*.545 380 


.545 388 ±06 


SII 


( 3 P)4p 4 D? /2 


- ( 3 P)4s 4 P 5/2 


57; 15-CW,U;43-A 


.547 360 


.547 374 ±06 


SII 


( 3 P)4p 4 D? /2 - 


- ( 3 P)4s 4 P 1/2 


57; 43-A 


.550 967 


.550 990 ±06 


SII 


( 3 P)4p 4 D 3 ° /2 


- ( 3 P)4s 4 P 3/2 


43 


.556 495 


.556 511 ±06 


SII 


( 3 P)4p 4 D 5 ° /2 


- ( 3 P)4s 4 P 5/2 


43 


*.563 999 


.564 012 ±06 


SII 


( 3 P)4p 2 D? /2 


-( 3 P)4s 2 P 3/2 


57; 15-CW,U; 43-A 


.564 698 


.564 716 ±06 


SII 


( 3 P)4p 2 D^ /2 


- ( 3 P)4s 2 P 1/2 


57; 43-A 


.581 919 


.581 935 ±06 


SII 


( 3 P)4p 2 D 3 ° /2 
7.6.3 SELENIUM 


-( 3 P)4s 2 P 3/2 


43 


.460 434 


.460 460 ± 50 


Sell 


( 3 P)5p 2 D? /2 


-( 3 P)5s 4 P 5/2 


119-CW.P 


.464 844 


.464 860 ± 50 


Sell 


( 3 P)5 P *P§ /2 - 


- ( 3 P)5s 4 P 1/2 


119-CW,P 


.476 365 


.476 410 ± 50 


Sell 


( 3 P)5p 2 D^ /2 


-( 3 P)5s 4 P 3/2 


119-CW 


.484 063 


.484 060 ± 50 


Sell 


( 3 P)5p 2 S? /2 - 


- ( 3 P)5s 4 P 3/2 


119-CW 


.484 496 


.484 500 ± 50 


Sell 


( 3 P)5p 4 S§ /2 - 


- ( 3 P)5s 4 P 5/2 


119-CW,G 


*.497 566 


.497 610 ± 50 


Sell 


( 3 P)5p 2 D? /2 


- 4s4p 4 2 P 3/2 


119-CW,G,P 



248 Handbook of Lasers 

TABLE 7. IONIZED GAS LASER TRANSITIONS (Continued) 



Wavelength, 


Measured 


Ion 


Identification 




fim 


value, fim 


Upper level — Lower level 


References 






7.6.3 SELENIUM (Continued) 




*.499 275 


.499 290 ± 50 


Sell 


( 3 P)5p 4 P2 /2 -( 3 P)5s 4 P 3/ 2 


119-CW,G,P 


*.506 865 


.506 870 ±50 


Sell 


( 3 P)5p*P°: /2 - ( 3 P)5s 4 P 5/2 


119-CW,G,P 


.509 650 


.509 610 ±50 


Sell 


?( 3 P)5p 4 D$ /2 - ( 3 P)4d 4 F 9/2 


8-U; 119-CW 


.514 214 


.514 190 ±50 


Sell 


( 3 P)5p 4 D§ /2 - ( 3 P)5s 4 P 1/2 


119-CW,G 


*.517 598 


.517 600 ±50 


Sell 


( 3 P)5p 4 D^ /2 - ( 3 P)5s 4 P 3/2 


119-CW,G,P 


*.522 751 


.522 760 ±50 


Sell 


( 3 P)5p 4 D? /2 - ( 3 P)5s 4 P 5/2 


8-U; 119-CW,G,P 


.525 307 


.525 260 ±50 


Sell 


( 3 P)5p 2 D? /2 - ( 3 P)5s 2 P 3/2 


119-CW,G 


.525 363 


.525 320 ±50 


Sell 


( 3 P)5p 4 D? /2 -( 3 P)5s 4 P 1/2 


119-CW,G 


.527 111 


.527 130 ±50 


Sell 


?( 3 P)5p 4 D? /2 - ( 3 P)4d 4 F 7/2 


119-CW 


*.530 535 


.530 550 ±50 


Sell 


( 3 P)5p 2 D§ /2 -( 3 P)5s 2 P 1/2 
(( 3 P)5p 4 P° /2 -( 3 P)5s 4 P 5/2 \ 


119-CW,G,P 


.552 242 


.552 280 ±50 


Sell 


or 
l( 3 P)5p 4 P° ;/2 -4s4p 42 P 3/2 J 


119-CW 


.559 116 


.559 160 ±50 


Sell 


( 3 P)5p 4 P? /2 -( 3 P)5s 2 P 1/2 


119-CW 


.569 788 


.569 790 ±50 


Sell 


( 3 P)5p 4 D? /2 -( 3 P)5s 4 P 3/2 


119-CW 


.574 762 


.574 790 ±50 


Sell 


( 3 P)5p 4 D§ /2 -( 3 P)5s 4 P 5/2 


119-CW 


.605 596 


.605 630 ± 50 


Sell 


( 3 P)5p 2 P?, /2 -"7" 


119-CW.G 


.644 425 


.644 390 ± 50 


Sell 


( 3 P)5p 2 Dg /2 -"7" 


119-CW 


.649 048 


.649 010 ±50 


Sell 


( 3 P)5p 4 D? /2 -( 3 P)5s 2 P 1/2 


119-CW 


.653 495 


.653 460 ± 50 


Sell 


( 3 P)5p 2 P? /2 -"9" 
7.6.4 TELLURIUM 


119-CW 



.545 40 
.557 634 
.564 05 
.570 821 
.593 618 
.624 549 
.634 97 
.703 904 



.545 400 ±50 
.557 600 ± 50 
.564 050 ±50 
.570 850 ±50 
.593 650 ± 50 
.624 550 ± 50 
.635 000 ±100 
.703 950 ± 50 



Tell? 

Tell 

Tell? 

Tell 

Tell 

Tell 

Tel? 

Tell 



5s 2 5p 2 ( 1 D)6p? /2 - 94860.95 (J = 5/2) 

103106.12(? /2 ) - 85592.36( 5/2 ) 
99585.02(§ , /2 ) - 82743.83( 3/2 ) 
99585.02(§ /2 ) - 83577.90( 1/2 ) 
?[not an ion line] 
97780.47(? /2 ) - 83577.90( 1/2 ) 



132 

9; 132-A 

132 

9; 132-A 

132-A 

132-A 

9-E 

132-A 



7.7 GROUP VII A 



275 958 


.275 959 ± 06 


Fill 


282 613 


.282 608 ± 06 


FIV 


312 151 


.312 156 ±06 


Fill 


317 413 


.317 418 ±06 


Fill 


320 275 


.320 274 ± 06 


FII 


402 472 


.402 478 ± 06 


FII 


263 267 


.263 270 ±06 


CI III 


319 146 


.319 143 ±06 


CI III 


339 287 


.339 287 ±06 


CI III 


339 343 


.339 345 ±06 


CI III 


353 004 


.353 003 ± 06 


CI III 


356 069 


.356 069 ± 06 


CI III 


360 210 


.360 210 ±06 


CI III 


361 283 


.361 210 ±06 


CI III 


362 268 


.362 269 ±06 


CI III 



7.7.1 FLUORINE 

( 2 P°)3p 3 D 3 - ( 2 P°)3s 3 P§ 
( 3 P)3p 4 D? /2 -( 3 P)3s 4 P 5/2 
( 3 P)3p 2 D§ /2 - ( 3 P)3s 2 P 3/2 
( 2 D°)3p 1 D 2 - ^D'WDS 
( 4 S°)3p 3 P 2 - ( 4 S°)3s 3 S? 

7.7.2 CHLORINE 

( 1 D)4d 2 D 5/2 -( 1 D)4p 2 F? /2 
( 3 P)4p 4 SI /2 -( 3 P)4s 4 P 5/2 
( 1 D)4p 2 Df /2 - ( 1 D)4s 2 D 3/2 
( 1 D)4p 2 D§ /2 -( 1 D)4s 2 D 5/2 
( 1 D)4p 2 F? /2 -( 1 D)4s 2 D 5/ 2 
( 1 D)4p 2 Fg /2 - (»D)4s 2 D 3/2 
( 3 P)4p 4 D? /2 - ( 3 P)4s 4 P 5/2 
( 3 P)4p 4 D? /2 -( 3 P)4s 4 P 3/2 
( 3 P)4p 4 D^ /2 -( 3 P)4s 4 P 1/2 



36-E 

36 

36 

36-E 

36 

36-E 



36; 111 

36-E 

36-E 

36-E 

36-E 

36-E 

36-E 

36-E 

36-E 



7 Ionized Gas Lasers 249 
TABLE 7. IONIZED GAS LASER TRANSITIONS (Continued) 



Wavelength, 


Measured 




Identification 


References 


[Ml 


value, fxm 




Upper level — Lower level 








7.7.2 CHLORINE (Continued) 




.372 046 


.372 046 ±06 


CI III 


( 3 P)4p 2 DS /2 - ( 3 P)4s 2 P 3/2 


36-E 


.374 882 


.374 878 ±06 


CI III 


( 3 P)4p 2 D| /2 -( 3 P)4s 2 Px/2 


36-E 


.413 250 


.413 250 ±10 


CI II 


( 2 D°)4p 1 D 2 - ( 2 D°)4s 1 DS 


137-CW,U 


.474 042 


.474 040 ± 10 


CI II 


( 2 P°)4p 1 P 1 - ( 2 P°)3d 1 DS 


137-CW.U 


.476 871 


.476 874 ±06 


CI II 


( 2 P°)4p 3 D 2 - ( 2 P°)4s 3 P? 


36; 137-CW.U 


.478 134 


.478 134 ±03 


CI II 


( 2 P°)4p 3 D 3 - ( 2 P°)4s 3 PS 


102; 15-CW,U; 103-A 


.489 685 


.489 688 ±03 


CI II 


( 2 D°)4p 3 F 4 - ( 2 D°)4s 3 D^ 


102; 15-CW,U; 103-A 


.490 482 


.490 473 ± 03 


CI II 


( 2 D°)4p 3 F 3 - ( 2 D°)4s 3 DS 


102; 15-CW.U; 103-A 


.491 781 


.491 766 ±03 


CI II 


( 2 D°)4p 3 F 2 - ( 2 D°)4s 3 D? 


102; 15-CW.U; 103-A 


.507 828 


.507 830 ±03 


CI II 


( 2 D°)4p 3 D 3 - ( 2 D°)4s 3 D^ 


102; 15-CW.U; 103-A 


.510 310 


.510 310 ±10 


CI II 


( 2 D°)4p 3 D 2 - ( 2 D°)4s 3 Dg 


137-CW.U 


*.521 792 


.521 790 ±03 


CI II 


( 4 S°)4p 3 P 2 - ( 4 S°)4s 3 S? 


102; 103-CW.A 


.522 135 


.522 130 ±03 


CI II 


( 4 S )4p 3 P! - ( 4 S°)4s 3 S? 


102; 15-CW.U; 103-A 


.539 216 


.539 215 ± 03 


CI II 


( 2 D°)4p 1 F 3 - ( 2 D°)4s 1 D5 


102; 15-CW.U; 103-A 


.609 472 


.609 474 ± 03 


CI II 


( 2 D°)4p 1 P 1 - ( 2 D°)4s 1 DS 


102; 15-CW.U; 103-A 






7.7.3 BROMINE 




.474 270 


.474 266 ± 03 


Br II 


( 2 P°)5p 3 D 3 - ( 2 P°)5s 3 P2 


85 


.505 465 


.505 463 ± 05 


Br II 


( 2 D°)5p 3 F 3 - ( 4 S°)4d 3 DS 


85 


.518 227 


.518 238 ± 02 


Br II 


( 4 S°)5p 3 P 2 - ( 4 S°)5s 3 S? 


85 


8-U; 15-CW.U 


.523 823 


.523 826 ±04 


Br II 


(*S )5p 3 P! - ( 4 S°)5s 3 S? 


85 


15-CW.U 


.533 205 


.533 203 ±03 


Br II 


^D^p^s - (^D^DS 


85 


8-U; 15-CW.U 


.611 761 


.611 756 ±06 


Br II 


( 4 S°)5p 5 P 2 - ( 4 S°)5s 3 S? 


86 


42 


.616 870 


.616 878 ± 06 


Br II 


( 4 S°)5p 5 P! - ( 4 S°)5s 3 S? 


86 






7.7.4 IODINE [Note 3] 




.453 379 


.453 379 ±03 


IIII, IV? 




90 


.467 440 


.467 440 ± 03 


mi, rv? 




90 


.493 467 


.493 467 ± 03 


iiii, rv? 




90 


.498 692 


.498 600 ± ? 


in 


( 2 D°)6p 3 D 2 - ( 4 S°)5d 3 D? 


80-A 


.521 627 


.521 600 ± ? 


in 


( 2 D°)6p 3 F 2 - ( 4 S°)5d 3 D? 


80-A; 135-hfs 


*.540 736 


.540 700 ± ? 


in 


( 2 D°)6p 3 D 2 - ( 2 D°)6s 3 DS 


55;59-hfs;80-A; 
135-hfs 


.562 569 


.562 500 ± ? 


in 


( 4 S°)6p 3 P 2 - ( 4 S°)6s 3 S? 


80 


*.567 808 


.567 800 ± ? 


in 


( 2 D°)6p 3 F 2 - ( 2 D°)6s 3 DS 


55;59-hfs;80-A; 
135-hfs 


*.576 072 


.576 000 ± ? 


in 


( 2 D°)6p 3 D 2 - ( 2 D°)6s 3 D? 


54; 59-hfs; 80-A; 
133-G; 135-hfs 


.606 893 


.606 890 ± ? 


in 


( 2 D°)6p 3 F 2 - ( 2 D°)6s 3 D x 


134-G; 135-hfs 


*.612 749 


.612 700 ± ? 


in 


( 2 D )6p 3 D x - ( 2 D°)6s 3 DI 


54; 59-hfs; 80-A; 
135-hfs 


.651 618 


.651 600 ± ? 


in 


( 2 D°)6p 3 F 2 - 5s5p 5 »PJ 


133; 135-hfs 


*.658 521 


.658 500 ± ? 


in 


( 2 D°)6p 3 D 1 - ( 2 D°)6s 3 D? 


55; 59-hfs; 80-A, E; 
135-hfs 


.682 523 


.682 523 ± ? 


in 


( 2 D°)6p 3 F 2 - ( 2 D°)6s 3 D 3 


134 


.690 477 


.690 400 ± ? 


in 


( 2 D°)6p 3 D 2 - CD^DS 


80-A, E 


*.703 299 


.703 200 ± ? 


in 


( 2 D°)6p 3 F 2 - ( 2 D°)5d 3 DS 


55; 59-hfs; 80-A; 
134-hfs 


.713 897 


.713 897 ± ? 


in 


( 2 D°)6p 3 D 2 - ( 2 D°)5d 3 D 3 


134 



3. Wavelengths and classifications for I II follow W. C. Martin and C. H. Corliss, 
Iodine (I II)," /. Res. Nat. Bur. Stand. (USA), 64A, 443-479, December, 1960. 



"The Spectrum of Singly Ionized Atomic 



250 Handbook of Lasers 

TABLE 7. IONIZED GAS LASER TRANSITIONS (Continued) 



Wavelength, 
(Mm 


Measured 
value, fxm 


Ion 


Identification 
Upper level — Lower level 


References 






1.1 A IODINE (Continued) 




.825 384 


.825 000 ±10 4 


III 


?( 2 D°)6p 3 D 1 - ( 2 D°)5d 3 Pg 


80-A 


.880 423 


.880 000 ±10 4 


III 


?( 2 D°)6p 3 F 2 - ( 2 D°)5d 3 F£ 


80-A 


1.041 72 


1.041 720 ±06 


I III, IV? 




90 


7.8 GROUP 






7.8.1 NEON 




[.235 796] 


.235 800 ±06 


NelV 


( 3 P)3p 4 D? /2 - ( 3 P)3s 4 P 5/2 


35 


[.247 340] 


.247 350 ± 06 


Ne III? 




35 


.267 790 


.267 798 ± 06 


NeHI 


( 4 S°)3p 3 P 2> o -( 4 S°)3s 3 S? 


22;35-A 


.267 864 


.267 868 ± 06 


NeHI 


( 4 S )3p 3 P! - ( 4 S°)3s 3 S? 


22; 35-A 


.277 765 


.277 750 ± 50 


NeHI 


( 2 D°)3p 3 D 3 - ( 2 D°)3s 3 D§ 


22 


[.286 688] 


.286 688 ± 06 


Ne 




22; 35-A 


.331 975 


.331 984 ±06 


Nell 


( 1 D)3p 2 P? /2 - ( 1 D)3s 2 D 3/2 


46; 35-A 


*.332 377 


.332 374 ±05 


Nell 


( 3 P)3p 2 P5 /2 -( 3 P)3s 2 P 3/2 


22; 39-S; 52-S,A; 
53-CW,G,P;110- 


?.332 437 


.332 437 ±10 


Ne 




CW,P 

46 


.332 717 


.332 750 ± 50 


Nell 


( 3 P)3p 4 D§ /2 - ( 3 P)3s 4 P 3/2 


22 


.332 923 


.332 902 ± 10 


Nell 


( 3 P)3d 4 D 7/2 -( 3 P)3p 4 D? /2 


46 


.333 114 


.333 107 ±10 


NeHI 


( 2 P°)3p 3 D 2 - ( 2 P°)3s 1 P? 


46 


*.334 552 


.334 550 ± 05 


Nell 


( 1 D)3p 2 P| /2 - ( 1 D)3s 2 D 5/2 


46-E; 35; 52-S,A; 
53-CW 


*.337 830 


.337 826 ±05 


Nell 


( 3 P)3p 2 P? /2 - ( 3 P)3s 2 P 1/2 


22; 52-S,A; 53-CW, 
G,P; 110-CW 


*.339 286 


.339 286 ±06 


Nell 


( 3 P)3p 2 P| /2 -( 3 P)3s 2 P 1/2 


22; 35-A; 53-CW,P 


.339 320 


.339 340 ±10 


Nell 


( 3 P)3d 2 D 3/2 -( 3 P)3p 2 D| /2 


46 


*.371 309 


.371 300 ±100 


Nell 


( 3 P)3p 2 D£ /2 - ( 3 P)3s 2 P 3/2 


26-CW,G; 53-CW,P 






7.8.2 ARGON 




.262 493 


.262 490 ± 06 


ArlV 


( 1 D)4p 2 D? /2 - ( 1 D)4s 2 D 5/2 


35 


[.275 392] 


.275 391 ± 06 


Arlll? 




22; 35-A 


.288 416 


.288 424 ± 06 


ArUI 


( 2 D°)4p 3 P 2 - ( 2 D°)4s 3 D? 


46; 35-A 


*.291 300 


.291 292 ±06 


ArlV 


( 3p )4p 2 D /2 _ ( 3p )4s 2p 3/2 


22;35-A;99-G 


*.292 627 


.292 624 ±06 


Ar IV 


( 3 P)4p 2 Df /2 - ( 3 P)4s 2 P 1/2 


22; 35-A 


[.300 266] 


.300 264 ± 06 


Ar 




22-E; 35-A 


.302 405 


.302 400 ± 50 


Ar III 


( 2 P°)4p 3 D 3 - ( 2 P°)4s 3 P2 


22 


.305 484 


.305 480 ±50 


Arlll 


( 2 P°)4p 3 D 2 - ( 2 P°)4s 3 P? 


22 


*.333 613 


.333 621 ± 06 


Arlll 


( 2 D°)4p 3 F 4 - ( 2 D°)4s 3 DS 


22; 35-A; 53-CW,G,P 


*.334 472 


.334 479 ±06 


Arlll 


( 2 D°)4p 3 F 3 - ( 2 D°)4s 3 D5 


22; 35-A; 53-CW.P 


*.335 849 


.335 852 ±06 


Arlll 


( 2 D°)4p 3 F 2 - ( 2 D°)4s 3 D? 


22; 35-A; 53-CW,P 


*.351 112 


.351 113 ±06 


Arlll 


( 4 S°)4p 3 P 2 - ( 4 S°)4s 3 S? 


102; 22-A; 52-S; 
53-CW,G,P; 
110-CW,P** 


.351 418 


.351 415 ±06 


Arlll 


CS^p 3 ?! - ( 4 S°)4s 3 S? 


102; 22-A; 29-CW 


[.357 661] 


.357 690 ± 50 


Aril 


( 3 P)4d 4 F 7/2 - ( 3 P)4p 4 D^ /2 


22-E 


*[.363 789] 


.363 786 ±04 


Arlll 


( 2 D°)4p 1 F 3 - ("D^^S 


102; 22-A; 26-CW.P; 
53-CW,G,P ** 


[.370 52] 


.370 520 ± 50 


Ar 




22 


.379 532 


.379 528 ±06 


Arlll 


( 2 P°)4p 3 D 3 - ( 2 P°)3d 3 PS 


22; 29-CW 



7 Ionized Gas Lasers 251 
TABLE 7. IONIZED GAS LASER TRANSITIONS {Continued) 



Wavelength, 


Measured 


Ion 


Identification 


References 


fim 


value, fJLtri 


Upper level - 


- Lower level 






7.8.2 ARGON (Continued) 




.385 829 


.385 826 ±06 


ArUI 


( 2 P°)4p 3 D 2 - 


( 2 P°)3d 3 P? 


22; 29-CW 


.408 86 


.408 860 ±20 


Ar 






29-CW,A; Note 4 


.414 671 


.414 660 ± 04 


Ar III 


( 2 D°)4p 3 P 2 - 


- ( 2 P°)4s 3 P5 


22; 29-CW 


*[.418 298] 


.418 292 ±06 


Ar III? 






22; 53-CW 


.437 075 


.437 073 ± 06 


Aril 


( 1 D)4p 2 D^ /2 


- ( 3 P)3d 2 D 3/2 


22; 24-CW 


.438 375 


.438 360 ±60 


Aril 


( 3 P)4p 4 S^ /2 - 


-( 3 P)4s 2 P 3/2 


109 


.448 181 


.448 200 ± 100 


Aril 


( 1 D)4p 2 D? /2 


- ( 3 P)3d 2 D 5/2 


16-CW; 92-CW 


.454 505 


.454 504 ± 10 


Aril 


( 3 P)4p 2 P^ /2 - 


- ( 3 P)4s 2 P 3/2 


20-G; 22-A; 68-CW 


*.457 935 


.457 936 ±16 


Aril 


( 3 P)4p 2 S? /2 - 


- ( 3 P)4s 2 P 1/2 


20; 11-G; 68-CW** 


.460 956 


.460 957 ± 10 


Aril 


( 1 D)4p 2 F? /2 - 


- ( 1 D)4s 2 D 5/2 


22 


.465 789 


.465 795 ±02 


Aril 


( 3 P)4p 2 P? /2 - 


- ( 3 P)4s 2 P 3/2 


20; 11-G; 68-CW 


.472 686 


.472 689 ± 04 


Aril 


( 3 P)4p 2 D§ /2 - 


- ( 3 P)4s 2 P 3/2 


20; 68-CW 


*.476 486 


.476 488 ± 04 


Aril 


( 3 P)4p 2 P^ /2 - 


- ( 3 P)4s 2 P 1/2 


20; 11-G,P,S;40-E; 
68-CW; 91-U,P ** 


*.487 986 


.487 986 ± 04 


Aril 


( 3 P)4p 2 D? /2 - 


- ( 3 P)4s 2 P 3/2 


20-E,G,P; 11-G,S; 
68-CW,P ** 


.488 903 


.488 906 ± 06 


Aril 


( 3 P)4p 2 P? /2 - 


- ( 3 P)4s 2 P 1/2 


22; 24-CW 


*.496 507 


.496 509 ±02 


Aril 


( 3 P)4p 2 D§ /2 


-( 3 P)4s 2 P 1/2 


20; 11-G,S; 68-CW** 


[.499 28] 


.499 255 ± 05 


Ar 






12 


*.501 716 


.501 717 ±02 


Aril 


( 1 D)4p 2 F? /2 


- ( 3 P)3d 2 D 3/2 


20; 11-G; 68-CW 


.514 179 


.514 180 ±05 


Aril 


( 1 D)4p 2 F? /2 


- ( 3 P)3d 2 D 5/2 


22; 24-CW 


*.514 532 


.514 533 ±02 


Aril 


( 3 P)4p 4 D£ /2 


- ( 3 P)4s 2 P 3/2 


20-G,P; 11-G; 
68-CW ** 


*.528 690 


.528 700 ±100 


Aril 


( 3 P)4p*Dg /2 


- ( 3 P)4s 2 P 1/2 


20; 68-CW 


.550 220 


.550 220 ±50 


ArUI 


( 2 D°)4p 3 D 3 - 


- ( 2 P°)4s 3 P^ 


22 


.673 000 


.673 000 ± 50 


Ar 






139 


.734 805 


.734 804 ± 05 


Aril 


( 1 D)3d 2 D 5/2 


- ( 3 P)4p 2 D? /2 


52-S 


.750 514 


.750 508 ± 05 


Aril 


( 1 D)3d 2 P 3/2 


- ( 3 P)4p 2 S? /2 


52-S 


.877 186 


.878 000 ±300 


Aril 


[( 3 P)4p 2 P§ /2 


-( 1 D)4s 2 D 5/2 ] 


123 


* 1.092 344 


1.092 300 ±100 


Aril 


( 3 P)4p 2 P| /2 - 


- ( 3 P)3d 2 D 5/2 


78-CW?,P; 23-CW; 
Note 5 






7.8.3 KRYPTON 






.264 927 


.264 941 ± 06 


KrII? 


?[( 3 P)5f 2 D^ /2 


- ( 3 P)4d 4 P 3/2 


35 


.266 441 


.266 450 ± 06 


KrII? 


?[( 1 D)5d 2 P 3/2 


-( 3 P)5p 4 D? /2 


35 


[.274 139] 


.274 151 ± 06 


Kr 






35 


[.304 970] 


.304 974 ±06 


Kr 






22; 35-A 


.312 438 


.312 443 ± 06 


KrIII 


^D^p^ 


- (^D^DS 


35 


.323 951 


.323 943 ±06 


KrIII 


( 2 P°)5p 1 D 2 - 


- ( 2 P°)5s 1 P? 


22; 35-A 


.337 496 


.337 500 ±50 


KrIII 


( 2 P°)5p 3 D 3 - 


- ( 2 P°)5s 3 P^ 


22; 53-CW 


*.350 742 


.350 742 ± 06 


KrIII 


( 4 S°)5p 3 P 2 - 


- ( 4 S°)5s 3 S? 


22; 53-CW,G,P; 
110-CW,P;** 


*.356 423 


.356 420 ±06 


KrIII 


CS^p 3 ?! - 


( 4 S°)5s 3 S? 


35; 53-CW,G,P 


.377 134 


.377 134 ±05 


KrII 


( 3 P)5d 4 P 1/2 - 


-( 3 P)5p 4 P^ /2 


52-P.S 


*.406 737 


.406 736 ± 06 


KrIII 


eDWF, - 


- (^D^DS 


22; 26-CW; 53-CW,P; 
95-CW,P 


*.413 133 


.413 138 ±06 


KrIII 


( 4 S°)5p 5 P 2 - 


( 4 S°)5s 3 S? 


22;53-CW,P;95-CW,P 


.415 444 


.415 445 ± 04 


KrIII 


( 2 D°)5p 3 F 3 - 


- ( 2 D°)5s 1 E>S 


22; 29-CW 



4. Ar, .40886 ju.m : This line was observed in a tungsten disk bore tube and is definitely an argon line (see Ref. 29 for de- 
tails). See also Note 1, above. 

5. Ar II, 1.092344 ^m: Over 10 mw CW power output was observed by G. N. Mercer (private communication) in a tube 
25 cm long. 



252 Handbook of Lasers 

TABLE 7. IONIZED GAS LASER TRANSITIONS (Continued) 



Wavelength, 


Measured 


Ion 


Identification 




fim 


value, fim 


Upper level - 


- Lower level 


References 






7.8.3 KRYPTON (Continued) 




All 179 


.417 181 ± 10 


KrIII 


Cs^sp 5 ?! - 


- ( 4 S°)5s 3 S? 


22 


.422 658 


.422 651 ± 06 


KrIII 


( 2 D°)5p 3 F 2 


- ( 2 D°)4d 3 D? 


22 


.431 781 


.431 800 ±100 


KrII 


( 3 P)6s 4 P 5/2 - 


-( 3 P)5p 4 P? /2 


96-P; 47-A 


.438 654 


.438 700 ± 100 


KrII 


( 3 P)6s 4 P 5/2 - 


-( 3 P)5p 4 P 3 ° /2 


96-E;47-A,E 


.444 329 


.444 328 ±04 


KrIII 


( 2 D°)5p 3 D 2 


- ( 2 D°)4d 3 D? 


22 


.457 720 


.457 720 ± 10 


KrII 


( 1 D)5p 2 F? /2 


-( 1 D)5s 2 D 5/2 


21;1-CW;22-A 


.458 285 


.458 300 ± 100 


KrII 


( 3 P)6s 4 P 3/2 - 


-( 3 P)5p 4 Di /2 


96; 47-A 


.461 528 


.461 520 ±10 


KrII 


( 3 P)5p a P§ /2 - 


- ( 3 P)5s 2 P 3/2 


107 


*.461 915 


.461 917 ± 10 


KrII 


( 3 P)5p 2 D| /2 


-( 3 P)5s 2 P 3/2 


21;22-A;23-CW 


.463 386 


.463 392 ±06 


KrII 


0D)5p 2 Fg /2 


- ( 1 D)5s 2 D 3/2 


21;22-A;24-CW 


?.465 016 


.465 016 ±10 


KrII 


( 3 P)5p 2 P? /2 - 


-( 3 P)5s 4 P 1/2 


22 


.468 041 


.468 045 ±06 


KrII 


( 3 P)5p 2 S? /2 - 


- ( 3 P)5s 2 P 1/2 


21;22-A;23-CW 


.469 444 


.469 500 ± 100 


KrII 


( 3 P)6s 4 P 5/2 - 


- ( 3 P)5p 4 D? /2 


96-P; 47-A 


.471 048 


.471 030 ±60 


KrIII 


( 2 D°)5p 3 F 4 - 


- ( 2 D )4d 3 D£ 


109 


.475 448 


.475 450 ± 30 


KrIII 


CD'WFa - 


- ( 2 D°)4d 3 D? 


109-E 


*.476 243 


.476 244 ± 06 


KrII 


( 3 P)5p 2 D§ /2 


-( 3 P)5s 2 P 1/2 


21 ; 7-U; 22-A; 1-CW 


.476 573 


.476 571 ± 10 


KrII 


( 3 P)5p 4 D? /2 


- ( 3 P)5s*P 3/2 


21;22-A;23-CW 


.479 633 


.479 630 ± 60 


KrII 


( 3 P)6s 2 P 1/2 - 


- ( 3 P)5p 4 S§ /2 


109 


.482 517 


.482 518 ±06 


KrII 


( 3 P)5p 4 SS /2 - 


-( 3 P)5s 2 P 1/2 


21; 22-A; 1-CW 


M84 659 


.484 666 ± 06 


KrII 


( 3 P)5p 2 P? /2 - 


-( 3 P)5s 2 P 3/2 


22; 23-CW 


.501 645 


.501 640 ±10 


KrIII 


( 2 D°)5p 1 D 2 - 


- ( 2 P°)4d 1 FS 


106; 139-CW 


.502 240 


.502 200 ±100 


KrII 


( 3 P)5p 4 D 3 ° /2 


-( 3 P)5s 2 P 3/2 


16;24-CW 


.503 747 


.503 750 ± 60 


KrII 






109 


.512 571 


.512 600 ±100 


KrII 


( 3 P)6s*P 3/2 - 


-?V)5tfT>% l2 


96; 47-A 


*.520 831 


.520 832 ±04 


KrII 


( 3 P)5p*Pg /2 - 


- ( 3 P)5s 4 P 3/2 


21; 7-U; 22-A; 23-CW 


.521 792 


.521 820 ±40 


KrII 


( 3 P)5p*D? /2 - 


- ( 3 P)5s 2 P 1/2 


109 


*.530 865 


.530 868 ± 04 


KrII 


( 3 P)5p*P£ /2 - 


- ( 3 P)5s 4 P 3/2 


21; 22-A; 23-CW 


.550 143 


.550 150 ±50 


KrIII 


( 2 D°)5p 3 F 3 - 


- ( 2 P°)4d 3 D2 


109-E 


.559 732 


.559 770 ±100 


KrIII 


( 2 D°)5p 3 P 2 - 


- ( 2 P°)5s 3 P2 


109 


*.568 188 


.568 192 ±04 


KrII 


( 3 P)5p*D§ /2 - 


- ( 3 P)5s 2 P 3/2 


21; 1-CW,P;7-U; 
22-A; 23-CW ** 


.575 298 


.575 340 ±50 


KrII 


( 3 P)5p 4 D£ /2 - 


-( 3 P)5s 2 P 1/2 


16; 15-CW; 139-CW.A 






( KrIII 


( 2 D°)5p 3 P 2 - 


-CP^s 1 ?? \ 




.593 503 


.593 530 ±60 


or 






109 






iKrll 


( 3 P)5d 4 F 3/2 - 


-CD)5p 2 P§ /2 J 




.603 716 


.603 760 ±80 


KrIII 


( 2 D°)5p 3 Pi - 


- ( 2 P°)4d 3 D? 


108 


.607 2 


.607 200 ±100 


Kr 






44 


.616 880 


.616 880 ± 50 


KrII 


CD)5p 2 F§ /2 - 


- ( 3 P)4d 2 D 3/2 


24-CW 


.631 022 


.631 030 ±80 


KrIII 


( 2 D°)5p 3 P 2 - 


- ( 2 P°)4d 3 D? 


108 


.631 276 


.631 260 ±80 


Kr 






108; 139-CW 


.641 661 


.641 700 ±100 


KrII 


( 1 D)5p 2 P^ /2 - 


- ( 3 P)4d 2 P 3/2 


44 


*.647 088 


.647 100 ±50 


KrII 


( 3 P)5p 4 P? /2 - 


-( 3 P)5s 2 P 3/2 


21; 1-CW; 
110-CW.P ** 


.657 012 


.657 000 ± 50 


KrII 


( 1 D)5p 2 DI /2 


-( 3 P)4d 2 F 5/2 


21 ; 24-CW 


.660 293 


.660 280 ± 80 


KrIII 


[( 2 D°)5p 3 P 2 - 


-ePWFS] 


108-E; 139-CW 


*.676 442 


.676 457 ± 10 


KrII 


( 3 P)5p 4 P? /2 - 


-( 3 P)5s 2 P 1/2 


21; 1-CW; 22-A** 


.687 084 


.687 096 ± 10 


KrII 


( 1 D)5p 2 F? /2 - 


- ( 3 P)4d 2 P 3/2 


21; 22-A; 24-CW 


.743 572 


.743 560 ± ? 


KrII 


( 1 D)4d 2 D 5/2 - 


-( 3 P)5p 4 D? /2 


118 


.752 546 


.752 550 ± 10 


KrII 


( 3 P)5p*P^ /2 - 


( 3 P)5s 2 P 1/2 


83-CW 


.793 145 


.793 140 ± ? 


KrII 


( 1 D)5p 2 F? /2 - 


-( 3 P)4d 2 F 5/2 


92-CW 



7 Ionized Gas Lasers 253 
TABLE 7. IONIZED GAS LASER TRANSITIONS (Continued) 



Wavelength, 

[Ml 



Measured 
value, /xm 



Ion 



Identification 
Upper level — Lower level 



References 



7.8.3 KRYPTON (Continued) 



*.799 322 


.799 300 ± 50 


KrII 


( 3 P)5p*Pg, 2 - 


( 3 P)4d 4 D 1/2 


21 ; 92-CW 


.828 037 


.828 030 ± 10 


KrII 


CD)5p 2 F§ /2 - 


-( 3 P)4d 2 F 5/2 


92-CW; 83-A 


.847 331 


.847 300 ± ? 


KrII 


( 1 D)4d 2 D 3/2 - 


-( 3 P)5p 4 D^ /2 


118 


[.858 778] 


.858 900 ±300 


KrIII? 






123 


.869 Oil 


.869 010 ± ? 


KrII 


( 3 P)5p 2 P? /2 - 


-eD)5s 2 D 3/2 


92-CW 


.897 859 


.897 840 ± ? 


KrII 


( 1 D)4d 2 D 5/2 


-( 3 P)5p*D§, a 


118-E 


1.065 950 


1.065 960 + 


KrII 


( 1 D)4d 2 D 5/2 


-( 3 P)5p 2 P§ /2 


118 


1.329 380 


1.329 500 ± ? 


KrII 


( 1 D)4d 2 D 5/2 


- ( 3 P)5p 2 D§ /2 


118 








7.8.4 XENON 




.247 739 


.247 739 ± 03 


Xe 






35;60-A 


.269 184 


.269 184 ±03 


Xe 






35;60-A 


?.298 385 


.298 370 ±50 


XeHI 


( 2 P°)6p 32 t - 


- ( 2 P°)6s 3 Pg 


22; 23 


.307 976 


.307 976 ±03 


Xe 






22-E; 35-A; 60-A 


.324 684 


.324 694 ±06 


XeHI 


( 2 P°)6p 3 D 3 - 


- ( 2 D°)5d 3 D| 


35 


[.330 604] 


.330 592 ± 06 


XelV? 






22-E; 35-A 


*.333 090 


.333 090 ± 03 


XelV 






22;28-CW;35;60-A; 
Note 6 


.334 980 


.334 980 ±03 


Xe 






35; 60-A 


*.345 424 


.345 423 ± 06 


XeHI 


^D^p^ - 


- ^D^DS 


35;53-CW,P 


.348 331 


.348 331 ± 03 


Xe 






22; 35; 60-A 


.354 233 


.354 231 ±05 


XeHI 


( 2 D°)6p 3 P 2 - 


- ( 2 D°)6s 3 D| 


52-S 


.359 660 


.359 600 ±100 


XeHI 






53-CW 


.364 551 


.364 551 ± 03 


Xe 






46-E; 35; 60-A; 
112-G,P 


.366 920 


.366 920 ± 03 


Xe 






35;29-CW;60-A 


.374 571 


.374 573 ± 06 


Xelll 


( 2 D°)6p 1 D 2 


- ^D'WDS 


35; 53-CW 


.375 994 


.375 994 ±03 


Xe 






22-E; 23-E; 60-A 


*.378 097 


.378 099 ± 06 


Xelll 


( 4 S°)6p 3 P 2 - 


- ( 4 S°)6s 3 S? 


22; 35-A; 53-CW,G,P 


.380 329 


.380 329 ± 03 


Xe 






35; 60-A; 112 






(Xe III 


( 2 D°)6p 3 F 2 


-( 2 D°)6s 3 D 2 > (.384 152)\ 




.384 1 


.384 100 ±100 


or 






29-CW 






IXe III 


( 2 D°)6p 3 P! - 


-( 2 D°)5d 3 D 2 '(.384 186)J 




.397 301 


.397 301 ± 03 


Xe 






35; 60-A; 112 






(Xe III 


( 2 D )6p 3 P! - 


- pD'WDS (.399 285) ^ 




.399 3 


.399 300 ± 100 


or 






109; 29-CW 






IXe III 


[( 4 S°)6p 5 P 2 


- ( 4 S°)5d 3 D? (.399 255)]J 




.405 005 


.404 990 ± 20 


Xelll 


( 4 S )6p 3 P! - 


- ( 4 S°)6s 3 S? 


108 


*.406 041 


.406 048 ± 06 


Xelll 


( 2 P°)6p32 1 - 


- ( 2 P°)5d25? 


22;45;46;53-CW,P; 

112 
109; 29-CW 


.414 572 


.414 530 ± 60 


Xelll 


( 2 D°)6p 3 D 2 


- ( 2 D°)5d 3 D? 


*.421 401 


.421 405 ±06 


Xelll 


( 2 D°)6p 3 P 2 


- ( 2 D°)5d 3 D§ 


22; 53-CW,G,P 


*.424 024 


.424 026 ± 10 


Xelll 


eD'WDz 


- ( 2 P°)5dl7S 


22; 53-CW.P 


*.427 259 


.427 260 ± 06 


Xelll 


( 2 D°)6p 3 F 4 


- ( 2 D°)5d 3 D§ 


22; 53-CW.P 



6. Xe, .3331, .4954, .5008, .5159, .526017, .5353, .5395, and .5956 fim: This set of xenon lines is very strong at high current 
densities (Refs. 112, 121) and CW operation has been obtained on five of these (Ref. 28). Correlation spectroscopy (Ref. 28) 
and current dependence suggest that all these lines belong to the Xe IV spectrum. See also Note 9. 



254 Handbook of Lasers 

TABLE 7. IONIZED GAS LASER TRANSITIONS (Continued) 



Wavelength, 



Measured 
value, [xm 



Ion 



Identification 
Upper level — Lower level 



.428 588 


.428 592 ±06 


Xelll 


.429 639 


.429 633 ± 05 


Xell 


.430 575 


.430 575 ± 03 


XelV 


.441 308 


.441 300 ±60 


Xe 


.443 415 


.443 422 ± 10 


Xelll 


.450 345 


.450 350 ±60 


Xelll 


.455 874 


.455 874 ±06 


XelV 


*.460 303 


.460 302 ± 04 


Xell 


.467 368 


.467 373 ±06 


Xelll 


.468 354 


.468 357 ±06 


Xelll 


.472 357 


.472 310 ±60 


Xelll 


.474 894 


.474 894 ± 03 


Xe III? 


.479 448 


.479 450 ± 60 


Xelll 


.486 249 


.486 200 ± 100 


Xell 


.486 946 


.486 948 ± 06 


Xelll 


.488 730 


.488 700 ± 100 


Xell 


*.495 418 


.495 418 ±03 


XelV 


.496 508 


.496 500 ± 06 


Xell 


.497 270 


.497 271 ± 05 


Xell 


*.500 780 


.500 780 ±03 


XelV 


.504 492 


.504 489 ± 06 


Xell 


.515 704 


.515 704 ±06 


Xe, IV, V? 


*.515 908 


.515 908 ±03 


XelV 


.522 364 


.522 340 ±60 


Xelll 


*.523 893 


.523 889 ±06 


Xelll 


.525 630 


.525 650 ±60 


Xe 


*.526 017 


.526 017 ±03 


XelV 



7.8.4 XENON {Continued) 

( 2 D°)6p 3 D 3 - ^D^DS 
( 3 P)7s 4 P 1/2 - ( 3 P)6p 4 P§ /2 
( 2 D°)6p 3 D 3 - ( 2 D°)5d 3 D 3 



( 2 D°)6p 3 F 2 - ( 2 D°)5d 3 D? 
( 2 P°)6p 32 x - ( 2 P°)5d 111 



( 3 P)6p 4 D^ /2 - ( 3 P)6s 4 P 3/2 

( 2 T>°)6p 1 F 3 - pD^DJ 
( 4 S°)6p 5 P 2 - ( 4 S°)6s 3 S? 
( 4 S )6p 5 P! - ( 4 S°)6s 3 S? 

( 2 D°)6p 3 D 1 - ( 2 D°)5d 3 D? 
( 3 P)7s 4 P 5/2 - ( 3 P)6p 4 P§ /2 
( 2 D°)6p 3 F 3 - ( 2 D°)5d 3 DS 
K 3 P)6p 2 P§ /2 - ( 2 P)6s 2 P 3/2 ] 



( 1 D)7s 2 D 3/2 - ( 1 D)6p 2 P° 3 /2 
( 1 D)6p 2 P^ /2 - ( 3 P)5d 2 D 5/2 



( 1 D)6p 2 P? /2 - ( 1 D)6s 2 D 3/2 



^D'WFa - ^D^d^S 
( 2 D°)6p 3 P 2 -( 2 P°)5dl3? 



References 



22 

52-P,S 

22-E; 45-E; 60-A; 

112-G,P;Note7 
109 

22; 139-CW 
109 

140; Note 8 
21;22-A;23-CW; 

63-CW,U 
22; 24-CW; 141-G,P 
22; 28-CW 
107 

24-CW; 60-A 
109 

97; 47-A 
22; 24-CW 
16-CW 
22; 28-CW; 45; 60-A; 

112-G,P;121-G,P; 

141-G,P; Note 9 
22; 15-CW 
75;45;52-S,A 
22; 28-CW; 45; 60-A; 

112-G.P; 121-G.P; 

141-P; Note 9 
21;22-A;23-CW: 

63-CW,U 
140 
22; 28-CW; 45; 60-A; 

112-G; 121-G,P; 

141-P; Note 9 
109 

22; 24-CW; 121 -A 
109 

22; 23-E; 30-CW; 45; 
60-A; 112-E,G,P; 121- 
G,P; 140-P; 141-G,P; 
Notes 9,10 



7. Xe, .430575 /xm: Gallardo, et al. (Ref. 60) question the assignment Xe III ( 2 D°)6p 3 D 3 — ( 2 D°)5d 3 D 3 ,. 430585 /mi given 
in Refs. 22, 23 because the wavelength for this assignment falls outside their measurement error. We have reexamined the original 
spectroscopic plates used in Ref. 22 and agree with their reevaluation. On these plates the line at .4306 /xm never occurred under 
the same discharge conditions as the lines .4214, .4273, and .4286 /mi, which have levels in common with the assignment given 
in Refs. 22, 23. Instead, the .4306 line occurred under the same conditions as those lines cited in Note 9. We therefore conclude 
that the laser line is an unclassified Xe IV line. 

8. Xe, .455874 /am. Ref. 140 reports this line is strongly anticorrelated with .53946, indicating that these two lines share a 
common upper level. This has been confirmed in unpublished correlation spectroscopy measurements by Bridges and Mercer 

9. Xe, .3331, .4954, .5008, .5159, .526017, .5353, .5395, and .5956 /xm: This set of xenon lines is very strong at high current 
densities (Refs. 112, 121) and CW operation has been obtained on five of these (Ref. 28). Correlation spectroscopy (Ref. 28) 
and current dependence suggest that all these lines belong to the Xe IV spectrum. 

In addition, Simmons and Witte have reported (Refs. 121, 122) a high-efficiency pulsed mode of operation yielding long 
pulses (up to 100 /xsec) at high power levels. They obtained a total of 10 kw peak output power from five of the green lines listed 
above, with an electrical efficiency of about 0.3 to 0.5 %. The laser used was 9 feet long, with a 1 cm inside diameter. It was 
filled with 7 mTorr of xenon and pulsed at currents of about 1500 amperes. 



7 Ionized Gas Lasers 255 
TABLE 7. IONIZED GAS LASER TRANSITIONS (Continued) 



Wavelength, 
fxm 



Measured 
value, [im 



Ion 



Identification 
Upper level — Lower level 



References 



.526 043 

*.526 195 

.531 389 

.534 334 

*.535 290 



.536 706 
*.539 460 



.540 100 

.541 353 

*.541 915 

.545 433 
.549 931 
.552 437 
.559 235 
.565 937 
.572 690 
.575 102 
.589 328 
*.595 567 



526 043 ± 03 


Xell 


526 150 ±100 


Xell 


531 400+100 


Xell 


,534 334 ±05 


XeIV,V? 


.535 290 ±03 


XelV 



7.8.4 XENON {Continued) 

( 3 P)6p 2 P§ /2 - ( 3 P)6s 2 P 1/2 

( 1 D)6p 2 D§ /2 - ( 1 D)6s 2 D 3 / 2 

( 3 P)7s 4 P 5/2 - ( 3 P)6p 4 D? /2 



.536 700 ±60 
.539 460 ±03 



540 090 ±30 


XeHI 




.541 350 ±60 


XeHI 




541 916 ±06 


Xell 




.545 460 ± 60 


XeHI 




.549 931 ± 04 


XelV, 


V? 


552 450 ±50 


XeHI 




.559 235 ± 05 


XelV, 


V? 


,565 900 ±100 


Xell 




572 700 ±100 


Xell 




.575 100 ±100 


Xell 




,589 330 ±03 


Xell 




.595 567 ±03 


XelV 





Xe III ( 2 D°)6p 3 F 2 - ( 2 D°)5d 3 D5 

Xe IV 



( 2 D°)6p 3 P 2 -( 2 P°)5dl5^ 
( 2 D°)6p 3 P 2 - ( 2 P°)5dl7§ 
( 3 P)6p 4 D° 5/2 - ( 3 P)6s 4 P 3/2 



( 4 S°)6d 5 Dg - ( 2 D°)6p 4 X 

^D^p^ - ( 2 P°)6s 3 P§ 

( 3 P)6p 2 P? /2 - ( 3 P)5d 4 P 1/2 
[( 1 D)6p 2 D? /2 - ( 1 D)5d 2 F 5/2 ] 
( 3 P)6p a D§ /2 - ( 3 P)5d 4 P 1/2 
( 1 D)6p 2 P^ /2 - ( 1 D)5d 2 D 5/2 



23;24-CW;60-A; 

Note 10 
21;22-A;23-CW; 

63-CW,U 
97-A,G;47-A 
121; 140-A 
22;28-CW;45;60-A; 

79-P; 112-G,P; 121- 

G,P; 140-P; 141- 

G,P; Note 9 
109-E 
22; 28-CW; 45-E; 

60-A; 112-G,P; 121- 

G,P; 140-P; 141-P; 

Note 8,10 
105 
109 
21;22-A;23-CW; 

63-CW,U 
109-E; 141-G,P 
121 ; 140-A 
24-CW 

121; 140-A,E;Notell 
16-CW; 23-E 
16-CW;23;47-E 
16-CW; 23-E 
52-S; 60-A 
22; 45; 60-A; 121-P; 

140-P; 141-P; Note 9 



9. Xe, .3331, .4954, .5008, .5159, .526017, .5353, .5395, and .5956 jtm: This set of xenon lines is very strong at high current 
densities (Refs. 112, 121) and CW operation has been obtained on five of these (Ref. 28). Correlation spectroscopy (Ref. 28) 
and current dependence suggest that all these lines belong to the Xe IV spectrum. 

In addition, Simmons and Witte have reported (Refs. 121, 122) a high-efficiency pulsed mode of operation yielding long 
pulses (up to 100 /usee) at high power levels. They obtained a total of 10 kw peak output power from five of the green lines listed 
above, with an electrical efficiency of about 0.3 to 0.5%. The laser used was 9 feet long, with a 1 cm inside diameter. It was 
filled with 7 mTorr of xenon and pulsed at currents of about 1500 amperes. 

10. Xe, .5260 ^m: The original spectrographic plates used by Bridges and Chester (Ref. 22) showed a line near .5260 ^m, 
whose wavelength appeared slightly different under two different operating conditions. A broad trace on the plate that was 
thought to represent both lines oscillating simultaneously was measured at .526017 ± 06 and assumed in Ref. 23 to represent 
simultaneous oscillation on two Xe II lines, .525992 and .526043, whose average is near the measured wavelength. In later work 
(Ref. 30), however, the plate was enlarged photographically to permit more accurate measurements. It was found that the broad 
trace on the plate was apparently a single laser line, but over-exposed because of its high intensity. A new measurement of this 
trace yielded .526018 ± 03 ^m. Under a different set of operating conditions, recorded also on the same plate, a single laser line 
was measured at .526044 ± 03 jim. The operating conditions that produced the .526018 line, as recorded by the plate, also pro- 
duced the other unclassified lines which are characteristic of xenon at very high current densities: .5956, .5395, .5353, .5159, 
.5008, and .4954 /^m; all these lines are currently thought to belong to the Xe IV spectrum (see note 9, above). The laser con- 
ditions producing the .526044 line produced none of these unclassified lines, but did produce a number of Xe II and Xe III lines; 
thus the .526044 line is no doubt correctly identified as a Xe II line, as indicated in the table. 

Gallardo et al. (Ref. 60), in independent work, have accurately measured many lines in xenon at high current densities, and 
have given special attention to the .5260 lines. They measure wavelengths for the lines as .526017 ± 03 pm (seen both in spon- 
taneous emission and as a laser line) and .526043 ± 03 /urn (seen only in spontaneous emission). Their conclusions about the 
identification of these lines agree with the discussion above. In addition, they publish a spectrogram in their paper, which shows 
both lines simultaneously in spontaneous emission, and well resolved from each other. 

11. Hoffmann and Toschek identify .559235 M m as Xe II ( 1 D)7s 2 D 3/2 -( 1 D)6p 2 D^ /2 , while the accepted wavelength for 
that transition is .559171 fxm. The precision of their wavelength measurement would rule out this identification. Further, the 
conditions under which they obtain this line are those favoring higher excitation states. 



256 Handbook of Lasers 

TABLE 7. IONIZED GAS LASER TRANSITIONS {Continued) 



Wavelength, 


Measured 


Ion 


Identification 




fj-m 


value, fxm 


Upper level — Lower level 


References 






7.8.4 XENON (Continued) 




*.597 111 


.597 112 ±06 


Xell 


( l V)6p 2 V% l2 -( l T>)6s 2 T> 3l2 


21;22-A;23-CW; 


.609 361 


.609 400 ±100 


Xell 


( 3 P)7s 4 P 3/2 - ( 3 P)6p 4 Dg /2 


63-CW.U 

47-A 


.617 619 


.617 619 ±03 


Xe 




108; 60-A; 139-CW 


.623 825 


.623 890 ± 80 


XeHI 


eDWFa-eP^dnS 


108; 139-CW 


*.627 081 


.627 090 ± 10 


Xell 


( 1 D)6p 2 F? /2 - ( 1 D)6s 2 D 3/2 


21;22-A;23-CW; 
63-CW.U 


.628 641 


.628 660 ± 60 


Xe IV, V? 




109; 141 


.634 318 


.634 318 ±30 


XeIV,V? 




141 P 


.652 865 


.652 850 ± 50 


Xell 


( 1 D)6p 2 F? /2 -(iD)5d 2 F 5/2 


24-CW; 63-CW,U 


.669 431 


.669 43 ± ? 


Xell 


( 3 P)6p*PS /a - ( 3 P)5d 4 D 1/2 


92-CW 


.669 950 


.669 950 ± 30 


XeIV,V? 




140 


.670 225 


.670 200 ± 100 


Xell 


( 1 D)6p 2 P 3 ° /2 -( 1 D)5d 2 F 5/2 


63-CW.U; 136 


.707 234 


.707 23 ± ? 


Xell 


37? /2 - ( 3 P)6d 4 D 5/2 


92-CW 


.714 903 


.714 894 ± 60 


Xell 


( 3 P)6p 4 D 3 ° /2 - ( 3 P)6s 2 P 3/2 


107-E; 92-CW; 63- 


*.782 763 


.782 800 ± 300 


Xell 


?35g /2 — 16 3/2 


CW,U 

123 


*.798 800 


.798 900 ± 300 


Xell 


( 3 P)6p 4 P? /2 -( 3 P)6s 4 P 1/2 


123 


.833 271 


.833 000 ± 300 


Xell 


?27? /2 -( 3 P)6d 4 D 5/2 


123 


.840 919 


.840 800 ± 300 


Xel 


(not an ion line) 


123-E; 4-A 


.844 619 


.844 300 ± 300 


Xell 


?27 5 ° /2 -( 3 P)6d 4 D 3/2 


123 


.856 688 


.856 688 ±03 


Xe 




123; 60-A 


.858 251 


.858 200 ±300 


Xell 


?31§ /2 - 10 5/2 


123 


*.871 617 


.871 400 ±300 


Xell 


( 3 P)6p 4 D^ /2 -( 3 P)5d 2 P 3/2 


123; 92-CW 


*.905 930 


.906 300 ±400 


Xell 


?27g /2 — 16 3/2 


123 


.926 539 


.926 500 ±400 


Xell 


?( 1 S)5d 2 D 3/2 - ( 3 P)6p 4 D? /2 


123 


.928 854 


.928 700 ±400 


Xell 


?13? /2 -( 1 D)5d 2 S 1/2 


123 


*.969 859 


.969 700 ± 200 


Xell 


( 3 P)6p 4 D^ /2 -( 3 P)5d 4 P 5/2 


123; 129-CW 


1.063 385 


1.063 400 ±600 


Xell 


( 3 P)6p 4 Dg /2 - ( 3 P)5d 4 P 3/2 


123 


* 1.095 


1.095 000 ±600 


Xe 




123 


7.9 MISCELLANEOUS 


.464 53 


.464 530 ± 50 


Ar? 




22 


.561 


.561 000 ± ? 


NorO 




98 


.562 


.562 000 ± ? 


NorO 




98 


.657 745 


.657 745 ± 12 


Ne?, He? 




22 



7 Ionized Gas Lasers 257 

ENERGY LEVEL DIAGRAMS 

Figures 7-2 through 7-10 give atomic energy level diagrams for some of the important ion laser 
species. The arrangement of levels differs somewhat from the conventional Grotrian diagram; in addi- 
tion, only known laser lines are indicated, rather than all observed spectral lines. Figures 7-2 and 7-3, 
for Cd II and Hg II, have a fairly simple format, and have been redrawn following the indicated 
references. Figures 7-4 through 7-10, for the noble gas ions, are necessarily more complicated and 
these are explained below. 

Explanation of Figures 7-4 through 7-10: Each known atomic energy state (up to the maximum 
energy indicated) appears as a horizontal line, and these states are classified in columns according 
to the orbital angular momentum, /, of the excited electron (/ =0,1,2 for s,p,d states). The configuration 
designations are given in the L-S (Russell-Saunders) coupling scheme, or as listed in Charlotte E. 
Moore, Atomic Energy Levels, N.B.S. Circular 467 (hereafter denoted AEL). Core configurations 
corresponding to unprimed and primed state designations follow AEL and are explicitly given at the 
bottom of the figures. Higher orbital states (f,g, etc.) are not shown, since very few laser lines are known 
to involve any of these levels. In addition, levels not yet assigned to the s,p, or d systems are omitted, 
even though some laser lines involve these levels. The total angular quantum number J of each state 
appears to the right of the horizontal line denoting that state. 

This arrangement of states in columns automatically separates states of even and odd parity, the 
latter being denoted °. Note that the only selection rules satisfied by all the laser lines are those of 
parity change and orbital momentum change (A/ = ±1); L-S coupling is badly enough violated in 
many of these atoms that changes in core configuration or total spin S are relatively common for laser 
transitions. Some lower states, for which there is no single excited electron, are merely placed in columns 
of the correct parity. 

Vertical lines and dots are used to connect states having a common state designation, differing 
only in their total angular momentum, /. 

The vertical scale represents energy of excitation above the ground state for the given ionic species. 
The left-hand axis is marked in thousands of cm" 1 , and corresponding tic-marks are indicated on the 
right-hand axis. In addition, the right-hand axis indicates energy in electron volts (8068 cm -1 = 1 eV). 
The energy placement of the atomic states is that given in AEL, with a few exceptions. The designation 
"LP." in the upper corners of each figure gives the ionization potential of the particular ion considered, 
in cm -1 and in eV. 

The diagonal lines drawn on the figures represent known ion laser lines. Their wavelengths (in 
air) are indicated in /mi, with four places accuracy. A dotted line means that the indicated transition 
is only one of several that could be responsible for the observed laser line. For Ar II and Kr II, the laser 
lines ending on the s 2 P energy states are listed in two separate columns, keyed to the corresponding 
upper energy levels; the transitions in these cases were so numerous that diagonal lines would have 
been difficult to distinguish. 

Other Reference Sources 

The spectroscopic literature abounds with Grotrian diagrams, which are similar diagrams, giving 
some or all observed spectral lines, rather than only laser lines. References to the original literature 
will be found in the footnotes of AEL: 

Charlotte E. Moore, Atomic Energy Levels, volumes 1, 2, and 3, N.B.S. Circular 467, Washington, 

D.C. 

A number of well-drawn Grotrian diagrams appear in the publication : 

Charlotte E. Moore and Paul W. Merrill, Partial Grotrian Diagrams of Astrophysical Interest, 
NSRDS-NBS 23, National Bureau of Standards, Washington, D.C, June, 1968. 

The publication by Moore and Merrill includes diagrams for the ion laser species Ca II, C III, Si II, 
N II, O II, O III, and S II. 

Finally, Grotrian's classic compilation may be consulted: W. Grotrian, Graphische Darstellung 
der Spektren von Atomen undlonen mit ein, zwei, und drei Valenzelektronen, volume II, Julius Springer, 
Berlin, 1928. Although the modern level nomenclature is somewhat different, Grotrian's collection is 



258 



Handbook of Lasers 



cd n 



130- 



120- 



(I.R 136374.74) 



(I.R 16.904) 



He + 



J P 



6g*G 



2_9p_p!i/ 2 3 /2_8 d 2 D 5/2 ^ 6f 2 p o 7 7/2 ^ 



^?PH 3 /2?d 2 D 5 /2 
-_2\ (/ 2 7p 2 P°3/ 2 




^i' *' 




CORE CONFIGURATIONS: 

(o) 10 i 

■ 4d ('S) 

7 = 4d 9 5s( 3 D ) 



-16 



-15 



•14 



-13 



•12(2 

o 

> 



■ II z 
o 

I- 

■10 ° 
_i 



-9 >- 
o 
q: 
uj 
z 
-8 w 



-7 



-6 



_-5 



Lo 

Fig. 7-2. (Adapted from an unpublished memo by Y. Sugawara, et al.) Partial energy level diagram of Cd II. Wave- 
lengths of spectral lines are given in /xm; those in parentheses are not known laser lines, but only spontaneous emission 
lines. Take note that the energies of the helium levels shown are measured from the Cd I ground state, which is 8.991 eV 
(72538.8 cm l ) below the Cd II ground state indicated as in the figure. Since the identification of the infrared laser 
lines .8390 and 1.1869 is uncertain, these are not indicated in the figure. 



7 Ionized Gas Lasers 



259 



(IP. 151280) 



Hg E 



(IP. 18.751) 



2 P° 



D 



2 F° 



o 

z 
< 

O 

X 



> 
o 
q: 
uj 

z 

UJ 



140— i 

130- 
120- 
110 — 

100- 
90- 
80 
70- 

60- 

50- 

40 

30- 

20- 

10 




0-l6s 



6p 



9d 
8d 



7f 
6f 



6g 



5g-^- 






^s^t, 



6s' 



CORE CONFIGURATION 
5d l0 ('s) 



-17 
--16 
_-l5 

-14 

-13 

-12 

--I I 

_-IO 



tf) 



o 
> 



o 

i— y i_ 
o 

UJ 

h8 -• 
' ui 



h7 5 

or 
~h6 £ 



Ui 



5 
-4 
-3 
-2 



Fig. 7-3. (Adapted from Ref. 13.) Partial energy level diagram of Hg II. Wavelengths are given in ^,m, and only 
known laser lines are indicated in the figure. Levels with excited d electrons, when indicated, are shown with dashed lines. 
Many of the higher lying doublets are not resolved in the scale to which the figure is drawn. For clarity, / values are 
indicated only for those levels participating in the laser transitions. 



260 



Handbook of Lasers 



(IP. 331350) 
330—i s 



320 — 



Ne H 



310 — 



280 — 



u. 270— 




240 — 



(Nell CORE CONFIGURATIONS : (o) = 2s 2 2p* ( 3 p ) 

' = 2s 2 2p«('D) 
" -- 2s 2 2p«( l S) 

Fig. 7-4. Energy level diagram for Ne II. See text for explanation of this 



figure. 



7 Ionized Gas Lasers 261 



(IP. 33I350) 
330— i s 



320 — 



3I0 — 



300— 



-• 5/2 , 3/2 

'2i 



4s" D 



290— 



280- 



u. 270- 
o 



4s 2p I/2 
V>3/2 




4s*P 



3S ,,2 S 



5/2 



I/2 



260 — 



Ne II 

P° 



3p" 2 P° 



(I.P. 41.07) 

d 

> j. < 3/ 2 



— 40 



— 39 




262 



Handbook of Lasers 



280 — 



270 — 



260 — 



250 — 



220 




240 — 



2 30— 



!NeIE) C0RE C0NF| GURATI0NS^ (o) = 2s*2p 4 ( 3 P ) 

' = 2s 2 2p 4 ('D) 
" -- 2s 2 2p 4 ('S) 



7 Ionized Gas Lasers 



263 



Ar H 



210- 



190- 




(ArJI) 



CORE CONFIGURATIONS 1 



1°) 



= 3s z 3p 4 ( 3 P) 



1 =3s 2 3p 4 ('D) 

" =3S 2 3P 4 ('S) 
Fig. 7-5. Energy level diagram for Ar II. See text for explanation of this figure. 



264 



Handbook of Lasers 



I8O-1 



(LP. 198182.00) 
S 



170- 



160- 



<-> 150 — 



1 140- 



130- 



120- 



110 - 




^A6*D X7/2 ~ 



1/2 



.6 2. 



10- 



(4s)4p°'S 



-14 



- I 



1/2 

4s 2 4p S2 P° 

3/2- 



(KrE 



CORE CONFIGURATIONS' 



= 4s 2 4p«(3p) 
' -. 4s 2 4P 4 CD) 



" = 4s 2 4p 4 ('S) 
Fig. 7-6. Energy level diagram for Kr II. See text for explanation of this figure. 



7 Ionized Gas Lasers 



265 



Xe H 



(IP. 171068.4) 



I6O-1 



-19 



-17 



-16 




o 

QC 



XeK) 



CORE C0NFI6URATI0NS : 



(0) =5s 2 5p 4 ( 3 P) 
/ »5s 2 5p 4 ( , D) 
" = 5s 2 5pVs) 



Fig. 7-7. Energy level diagram for Xe II. See text for explanation of this figure. 



266 Handbook of Lasers 



(IP 329.965 80) 




(ArlH ) CORE CONFIGURATIONS 

'"'o.'sp'lVl 
' . Ji'3pVd°i 

Fig. 7-8. Energy level diagram for Ar III. See text for explanation of this figure. 



7 Ionized Gas Lasers 



267 



290 H 



280- 



270- 



260- 



250- 



240- 



230- 



220- 



i 

s 

o 



210 - 



(IP 329965.80) 

,o 



(' 

// 3„o 



5s" 3 P 



/3„0 \ 



5s' - D 



5s a S 



3 C o 



5 s °S 



5 e o 



Arm 

P 



(LP. 40.90) 

,o 



I 

3 o //2 
D ^3 



WW j, 




>^ 



j(" v | 




— 35 



— 34 



— 33 



32 



•31 



— 30 



—29 



28 



— 27 



o 

> 



"—26 o 



268 Handbook of Lasers 



250- 



240- 



230- 



220- 



i 

s 
o 



< 



© 

x 



210 



190- 



180- 



170- 




tx. 200-^—. 2 



7 Ionized Gas Lasers 269 



190- 



180 



170- 



160- 



150- 



140 




4s 3 S° 



2 



4s 5 S e 



(3s)3p 5, P° 



r* 



115 



110- 



& 



\2 

(3s)3p 53 P° 



15- 



10- 



5- 



I 



ArM) 



3$ 2 3p 4l S 

(33265.7cm"') 
• 



3s 2 3p 4, D 



3s 2 3p 43 P 

— I 2 - 



CORE CONFIGURATIONS^ 



(0, «35 2 3p 3 ( 4 S°) 
'.3s 2 3p 3 ( 2 D°) 

II 2_ 3.2 O 

«3S 3p ( P ) 




— 23 



/In© 



3d"P 



^4 



■^H 



— 22 



— 21 



-20 



-19 



-18 



-14 



i 



270 



Handbook of Lasers 




CORE CONFIGURATIONS ' 



'-'■4.'4 P VS°) 
' ■4i'«p , ( , D°) 
* ■4f , 4p»( , P l 



Fig. 7-9. Energy level diagram for Kr III. See text for explanation of this figure. 



7 Ionized Gas Lasers 271 



(IP 298020) 



Kr HI 



(I.P.36.9) 



6s"' P° 



250 - 



6s 7 ' 3 P° 



240- 



6s"D°? 



ss^d 



230- 



6s* S 



3 c© 



220- 



6s°S 



5eO 



2I0 



200- 



I90- 



° I80- 



5s J P 



^it^^ 



5d 



/l G o 



5d''D ? 



-29 



-28 



^5d3 D ° 






5d°D 



5n° 



\ 




31 



30 



-27 



--26 



25 



— 24 



23 



o 
22 > 



272 Handbook of Lasers 



220- 




-27 



--26 



-25 



-24 



-23 



o 
22 > 



o 



-21 



>• 

DC 



20 



— 19 



— 18 



17 



7 Ionized Gas Lasers 273 



60- 



50- 




140- 



30- 



120- 



10- 



5s 3 S 



5s 5 S 



5c° 



(4s)4p 5 'p° 



I 

(4s)4p 5 3 P° 

2 



J 



15^ 



10 



5- 



(KrUI) 



4s 4p 4 'S 

(33079 cm-') 
• 



4s 2 4p 4, D 



/" 



M 

4s 2 4p 4 3p 
2 - 



CORE CONFIGURATIONS 



{0, = 4s 2 4p 3 ( 4 S°) 

' =4s 2 4p 3 ( 2 D°) 
" = 4s 2 4p 3 ( 2 P°) 



4d ,l G° 



<4 



'TTv^ 3 



t" 4 

<-3 



*-2 

4d / 3 F° 



!=^ 3 
4 -2 



I - 



4d 3 D° 



— 18 



^4dV ^ ; 



2 
I 




20 



19 



— 17 



— 16 



15 



— 14 



— I 



274 



Handbook of Lasers 



XeH 



IIP 259089) 

s° 



190 — 



180 — 



I 70— 



-23 



-22 



-21 



-20 




XelH) 



CORE CONFIGURATIONS 



(°) 



' 5«*5p s rs") 
■ 5s 2 5p 3 (V) 



Fig. 7-10. Energy level diagram for Xe III. See text for explanation of this figure. 



7 Ionized Gas Lasers 



275 



XelE 



(I P 259089 
o 



90— 



80 — 



70— 



I 60— 



50- 



CO 



I 40 — 



I 3 — 



20 — 




-23 



— 22 



-21 



-20 



-19 



-18 



-17 



o 

> 



o 



>- 
q: 



-16 



-15 



276 



Handbook of Lasers 




o 

> 



o 
cc 



XeUr 



CORE CONFIGURATIONS : 



5s 2 5p 3 ( 4 S°) 



5s<5p*(V) 

" c 2 r 3,2 4 

= 5s 5p ( P ) 



7 Ionized Gas Lasers 277 



quite complete. Those diagrams most relevant to ion laser work are Ca II, Sr II, Zn II, Cd II, Hg II, 
B II, In II, C III, Si II, Si III, Si IV, Ge II, Sn II, Pb II, N III, P III, P IV, S IV, and S V. 

Finally, the laser literature contains less complete, but still useful, partial energy level diagrams, 
usually only including the most important laser levels. A partial listing of these diagrams appears below. 





Laser references 


Ion laser 


with 


species 


energy level diagrams 


Znll 


82 


CdH 


77 


HgH 


2, 13, 66, 128, 136 


Br II 


86 


III 


55, 133 (hfs: 59, 135) 


Aril 


20-E, 25, 41 


Kr II 


96 


Xell 


72, 97 


XelH 


72 



DISCUSSION OF PRACTICAL ION LASERS 

Of all the elements and their various states of ionization, only a very few have been developed as 
practical laser devices. The most commonly used ion lasers are the familiar blue-green transitions in 
Ar II. These are followed in popularity by the red and yellow Kr II lines, the Cd II blue and uv lines, 
the Ne II, Ar III and Kr III uv lines and, for some special applications, the red Hg II line. Very few 
other ion lasers have experienced development beyond the laboratory demonstration stage. Recent 
developments may allow the Xe IV (?) blue-green and uv lines to join the ranks of working lasers, even 
before their transitions are identified. 28,79 ' 112,121 Otherwise, the selection of truly useful lasers is 
limited. In the sections following, very brief descriptions are given of the more important types, 
including a discussion of mechanisms, scaling laws and output characteristics. Very little is given 
on technology, since this is the fastest moving and generally most difficult-to-pin-down aspect of 
any device until it has reached its maturity. 

It is not practical to discuss the lasers in the exact order in which they occur in the line list, but 
they are gathered together into groups with similar characteristics. That is, Cd II and Zn II together; 
Ar II and Kr II together; and Ar HI, Kr HI, Xe III, Ne II (ultraviolet) together. 

CADMIUM AND ZINC ION LASERS 

The first observation of laser oscillation in cadmium and zinc vapor by Fowles and Silfvast 56 did 
not create much excitement since, by that time (1965), many elements had lased as ions in simple 
pulsed discharges. It was not until low threshold, cw operation was observed in Cd II 0.4416 /im by 
Fowles and Hopkins 58 and Silfvast 116 that this particular laser took on a practical significance. The 
further observation of cw ultraviolet oscillation at 0.3250 pm by Goldsborough 64 added to the interest. 

Mechanisms 

The operating characteristics of the cw Cd II and Zn II lasers are quite different from those of the 
more well known noble gas ion lasers, discussed later. It is not surprising that the excitation mechanisms 
should also be different. Their operating characteristics are much more like the familiar neutral atom 
helium-neon laser; in fact, helium-cadmium and helium-zinc are better names, since helium is apparently 
a necessary constituent for low threshold cw operation. 

The exact role that helium plays in exciting the Cd II or Zn II levels is not known. Silfvast 117 has 
proposed the Penning mechanism, whereby a metastable helium atom produces an excited Cd or 
Zn ion: 

He* + Cd ► He + (Cd + )* + e" (a) 



278 Handbook of Lasers 

His arguments are based largely on the critical pressure dependence of the excitation process, charac- 
teristic of Penning reactions. On the other hand, Jensen and Bennett 81 have concluded that the higher- 
lying levels in zinc are populated by charge-exchange collisions: 

He + +Zn > He+(Zn + )* (b) 

and that the same process is probably also active in cadmium (see the appropriate energy level diagrams 
for the relative positions of He + , He* and the Cd laser levels). Jensen and Bennett conclude, however, 
that the 4s 2 2 D levels in Cd are populated by a different mechanism, but their work indicates that the 
Penning mechanism is not adequate to explain their observations. They propose as a possible mechanism 
the recombination of molecular ions: 

He 2 + + Zn > 2He +(Zn + )* (c) 

or possibly electron excitation by removal of an inner electron: 

Zn (3d 10 4s 2 ) + e~ > Zn + (3d 9 4s 2 ) + 2e" (d) 

somewhat analogous to the single-step electron excitation originally proposed by Bennett, et al. for 
the Ar II laser. 11 In any case, the exact path of excitation is not known for the Cd II and Zn II levels, 
but it is clear the helium is essential. 

The lower laser levels are assumed to be depopulated by radiative processes. Sugawara, et al. 121 
have proposed a cascade of radiative processes for the higher lying levels. 

Typical Operating Parameters and Scaling Laws 

Much less has been published on cw He-Cd operation than on the noble gas ion lasers. However, 
the relatively simple technology required to reach the highest powers obtainable has allowed a fairly 
complete description of the operating parameters of the 0.4416 and 0.3250 jum lines by Goldsborough 65 
with some additional confirmation by Hodges. 77 Using cataphoretic flow to stabilize the Cd vapor 
pressure in the discharge, Goldsborough reports the following optimum conditions for a 2.4 mm 
diameter tube at 0.4416 im\ output 

helium pressure = 3.4 Torr discharge current =110 mA 
cadmium pressure ^ 2 mTorr 

The 2 mTorr value corresponds to the vapor pressure of cadmium at ~233°C. The cadmium pressure 
is quite critical, with the output power falling off drastically at 1 and 3 mTorr. The output power 
obtained was approximately 200 mW from a 143 cm long discharge, or 31 mW/cm 3 . An earlier 3 mm 
bore tube produced ~ 10 mW/cm 3 . On the basis of measured population densities in a 3 mm diameter 
tube and lifetime data from the literature, Hodges calculates 12 mW/cm 3 as the maximum available 
power. 77 This agreement supports the contention that the lower laser level is well-depopulated. 

Goldsborough reports that further experiments with different discharge tubes show that the 
optimum pressure, longitudinal voltage gradient, and gain vary inversely with bore diameter, while 
the optimum current is proportional to bore diameter. The product of optimum current and optimum 
voltage gradient is approximately 3W/cm input power. These scaling laws have the same form as those 
for the helium-neon laser, which strongly suggests that helium metastables produce the upper level 
population, despite the arguments of Jensen and Bennett. 81 

The power output at 0.3250 /m\ should be about 16% of the 0.4416 fim output based on relative 
transition probabilities and measured populations. 77 Goldsborough has observed about 10%, which 
is in good agreement, considering the probable higher loss of the ultraviolet optics. 

NOBLE-GAS ION LASERS 

Much more has been published about the mechanisms and characteristics of the noble gas ion 
lasers, particularly Ar II, than any of the others. Only a brief synopsis can be given here of the impor- 
tant features; and no attempt will be made to cover the technology associated with practical sources. 
Some of these technology problems are discussed in Refs. 25, 29, 31, 67, 71, 93, 95, 138, 142, and 143. 
Many additional references to papers containing technology information are given in Ref. 142. 



7 Ionized Gas Lasers 279 

Mechanisms 

Historically, the first model of ion laser excitation was that proposed by Gordon, et a/., 93 ' 104 
shown schematically in Figure 7-1 1(a). In this model, the upper laser level is excited by an electron 
collision with an ion in its ground state (process (2)); the ion is assumed to have been created by a 
collision of an electron with a neutral atom in the ground state (process (£>). Cascade from higher 
states and destruction by electrons are neglected. The lower level is assumed to be rapidly depopulated 
by radiation (in the vacuum ultraviolet ~ 740 A for the 4s states of Ar II). The depopulation is assumed 
to occur much more rapidly than collisional electron excitation (dotted arrow). If the further assump- 
tions of approximate charge neutrality in the plasma and current-independent electron temperature 
are made, then the upper laser level population N 2 varies as 

N 2 ~n eni ~n e 2 ~J 2 (1) 

where « e , n i9 and J are the electron density, ion density and discharge current density respectively. 
This quadratic current dependence has been observed in spontaneous emission measurements over a 
wide range of currents, gas pressures and tube dimensions typical of cw ion laser operation (see, for 
example Refs. 25, 29 and 143). 

An alternate excitation model involving a single electron collision, as shown in Figure 7-1 1(b), 
was proposed by Bennett, et al. 11 This mode of operation apparently does occur in low pressure, short- 
pulse-excited discharges. A very high E/p is required to create a sufficiently high electron temperature 
to achieve single step excitation. This mode of operation is also characterized by a different output 
spectral distribution. For example, in Ar II .4765 /.im is the strongest laser line. This distribution is 
never observed in cw operation, where the .4880 pim and .5145 /mi lines are always dominant. (An 
energy level diagram for the 4p -> 4s Ar II laser transitions is shown in Figure 7-5 for reference.) In 
addition, the single step process, with constant electron temperature, would yield spontaneous emission 
from the upper laser level, which varies linearly with discharge current. 

One of the arguments advanced by Bennett, et al. 11 for the single-step process involves the favorable 
selection rules for excitation from the 3p 6 neutral ground state to the 3p 4 ( 3 P)4p excited ionic state 
(which does have a change in parity even though it is a p -> p transition, because of the electron lost 
in ionization). The highest yields are expected for the 3p 4 ( 3 P) 2 4p 2 P° levels, and hence the prediction 
of the .4765 fim = 4p 2 P3 /2 -» 4s 2 P 1/2 as the strongest transition. In fact, this line was observed by 
Bennett, et al. to be the strongest in a discharge with E/p ~ 1000 V/cm-Torr and excitation pulse ~20 
nsec. More recent experiments by Kobayashi, et al. 89 and Demtroder 49 confirm that there are two 
discharge regimes: (1) short pulse, low pressure and (2) long pulse/cw, high pressure. The .4765 /mi 
line was also the only line observed by Kulagin, et al. 91 in a very high current (15 kA), self-constricted 
discharge operated at E/p > 1000 V/cm-Torr and ~200 nsec pulses. 

Arguments based on selection rules weigh against the two-step process of Figure 7-1 1(a), because 
it requires a 3p 5 -*3p 4 ( 3 P)4p excitation, a violation of the dipole selection rules. In fact, it would seem 
that the transition to the lower laser level, 3p 5 -> 3p 4 ( 3 P)4s, would be more probable. However, the 
dipole selection rules arise from the Born approximation, which is valid only for electron energies well 
above threshold for the excitation. Since the electron temperature is small compared with the threshold 
energy for excitation (particularly under conditions of cw laser operation), most of the excitations 
actually take place quite near threshold. As pointed out by Massey and Burhop, 100 in this energy region 
the Born approximation does not hold, and excitation cross sections for transitions with no parity 
change (such as the 3p 5 -> 3p 4 ( 3 P)4p excitation) can even exceed cross sections for " optically allowed " 
excitations. An alternative answer proposed by Labuda, et al. 9 * is that ionic metastables serve as the 
intermediate species, rather than the ion ground state. This is shown schematically in Figure 7- 11(c). 
Absorption measurements 94 show these metastable levels to be highly populated. 

The ionic metastables are populated either by electron collision with the ionic ground state 
(process (T) in Figure 7-1 1(c)) or, more probably, by cascade from higher-lying states (process (2)) which 
exhibit populations N x ~J 2 (from spontaneous emission data). It can be argued that the metastable 
population N M will be proportional to J rather than J 2 , however, because it is primarily destroyed by 
electron collisions (see Ref. 25 or 94 for the argument). The upper laser level is then populated by a 
second electron collision (process (3)), which is more readily permitted by selection rules (requiring at 



280 Handbook of Lasers 



4p- 



3P 6 



•Ar + 3p ! 



3p e 



7\ 



X(p, f) 




M(s,d) 



Fig. 7-11. Possible upper laser level excitation methods for the blue-green transitions in Ar II (Ref. 25). 



most only a core or spin change rather than a parity violation), and the relation N 2 ~ J 2 is obtained 
as before. 

The picture of the upper level excitation process remained essentially as described above until 
measurements made by Rudko and Tang were reported. 113 Their measurements indicated that a signi- 
ficant fraction of the upper laser level population was created by radiative cascade from higher-lying 
states (see Figure 7-1 1(d)). By summing the spontaneous emission intensities of all lines terminating 
on a given upper laser level (for example, 4p 2 Ds /2 , the upper level of the .4880 /mi transition), and 
then comparing this with the sum of intensities of those lines originating from that level, we may deter- 
mine the population fraction due to cascade from the higher-lying states. Rudko and Tang reported 
that approximately 50% of the 4p 2 Dg /2 level population is created by cascade, in a 1 mm diameter 
tube operated without a magnetic field. Similar measurements were made by Bridges and Halsted, 25 
who obtained a value of 23% for the cascade contribution to this same level in a 3 mm diameter tube 
operated without a magnetic field, and 22% for the cascade contribution to the 4p 4 Ds /2 (.5145 /mi) 
upper level. Since the populations, N c , from which the cascade takes place also exhibit a quadratic 
dependence on J, the same quadratic dependence N 2 ~ J 2 results again. The point is that the fraction 
due to cascade cannot be separated from that due to two-electron-collision processes by its current 
dependence. 

Trapping of the vacuum uv radiation, which depopulates the lower laser level, N t , can upset the 
simple quadratic variation predicted above. The amount of trapping in cw operation is generally thought 
to be small (see, for example, Refs. 25 or 88 for a discussion), but it definitely shows up in pulsed ion 
laser operation. Figure 7- 12(a) shows the different time variation of the usual blue-green Ar II lines 
in a small pulsed laser, when an approximately square current pulse of 50 /*sec. duration is applied. 
The different shapes reflect the different time histories of the population differences (N 2 (t) — N t (/)) 
for each line. By comparison with spontaneous emission data (which gives only N 2 (t)), it is clear that 
the primary peculiarities in shape are caused by N^t), evidently due to the complex behavior of the 
excitation and trapping functions for the lower levels. Figure 7-12(b) shows the effect of trapping on a 
single line (0.4880 /mi) as the discharge current is increased. A region of decreased inversion develops a 
few microseconds after the leading edge of the current pulse as the current is increased. Eventually the 
inversion (N 2 — JVj) goes to zero (or even becomes negative for a period, as shown by Gordon, 69 and 
then recovers. The recovery is presumed to be due to a decrease in the radiation trapping coefficient 



7 Ionized Gas Lasers 281 

caused by Doppler broadening of the vacuum uv line as the gas temperature rises. The result is typically 
the "double pulse" output exhibited in the lower four oscilloscope traces of Figure 7- 12(b). If the 
current pulse rises slowly enough, the "first" pulse often disappears completely, since trapping causes 
the lower level to fill up faster than the upper level is populated. The resulting laser output appears to 
be simply delayed by several microseconds. The amount of delay depends on the gas pressure (longer 
for higher pressures), the kind of gas (longer for krypton and xenon than argon), and the magnetic 
field (longer if a magnetic field is used). All these dependencies point to gas heating (or rather, increased 
ion velocities) as the mechanism that reduces the trapping and allows the inversion to be reestablished. 

Scaling Laws 

With the addition of several simplifying assumptions (see Ref. 25) a simple scaling law for cw ion 
lasers can be derived: 

p/K = 10~ 5 J 2 (2) 

In eq. (2) Pj Vis the multimode, multicolor output from the blue-green Ar II lines in cw operation, per 
volume of active region (in W/cm 3 ), and J is the discharge current density in A/cm 2 . The simplified 
theoretical argument given in Ref. 25 only predicts the quadratic dependence in eq. (2); the constant 
of proportionality of 10 -5 W-cm/A 2 was determined empirically from measurements on many lasers 
in the 1-10 watt output range. Figure 7-13 shows some early results for 1.8-8 mm diameter tubes (from 
Ref. 25); the dotted line is eq. (2). More recent data continue to follow the rule to higher P/V. Similarly, 
Figure 7-14 shows data replotted from Ref. 93; again, the dotted line is eq. (2). Equation (2) actually 
holds over a wider range of dimensions and current than these curves would indicate, provided the gas 
pressure is reoptimized at each point (or, equivalently, if the envelope of several P/V vs. J curves at 
different gas pressures is taken for eq. (2)). Although based on rather rough assumptions, eq. (2) seems 
to serve as a good design law for P/V at least up to 10 W/cm 3 . Similar equations may hold for other 
singly-ionized lasers such as Ne II, Kr II, etc., but with a different constant of proportionality, provided 
the assumption of rapid lower level depopulation holds in these lasers. There is some evidence that 
this assumption is violated in Kr II and Xe II (see discussion below). 

Typical Operating Parameters 

That the curves of P vs. J (or P vs. I) deviate from the simple quadratic dependence given by eq. (2) 
at a fixed gas pressure is well known. At low currents the laser is nearer threshold and exhibits a much 
steeper variation of output with current, because it behaves as an inhomogeneously broadened medium. 
(True inhomogeneous broadening would yield a quartic dependence of power on current.) At the 
highest currents, the neutral atom density in the active region is depleted by the discharge ionizing the 
gas to still higher states and driving it from the small-bore (active) region into the (cooler) electrode 
regions. The relative importance of these two processes is not known, but they both result in a sub- 
quadratic dependence at high currents. However, if the total gas pressure in the laser is increased the 
P vs. /curve becomes steeper and continues to higher currents, so that a set of P vs. /curves at different 
fill pressures overlap to form an envelope, as shown in Figure 7-15. The envelope exhibits an I 2 de- 
pendence over a much wider range than any individual curve. (See Ref. 143.) 

Figure 7-16 shows the typical distribution of the blue-green wavelengths from an Ar 11 laser (the 
same tube as in Figure 7-15). This tube is described in detail in Ref. 31. These curves were taken with 
laser mirrors that had roughly the same reflectivity across the .5200-.4000 pim range. Different wave- 
lengths can be emphasized by tailoring the laser mirror reflectivities; for example, the 0.4880 /mi line 
has the highest gain, and can be emphasized by using a high transmission output mirror. The 0.5145 /mi 
line can be emphasized by using higher reflectivity mirrors biased toward the green. An intracavity 
dispersive element, such as a prism, can be used to select an individual wavelength. However, the power 
output on the wavelength selected will not necessarily be more than if the same wavelength were 
selected by a prism outside the laser, since competition effects are small or zero. The two strongest 
lines, 0.4880 /im and 0.5145 /mi, for example, do not compete even though they share a common lower 
level. The situation is different for the strong red and yellow lines of Kr II, the 0.6471 /an and 0.5682 /im 
lines, which also share a common lower level (in fact, the level in Kr II analogous to the 0.4880/0.5145 



282 



Handbook of Lasers 



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7 Ionized Gas Lasers 283 






z 

Ul 

o 
w 
o 



0.0 




0.05 - 



100 500 

(J) CURRENT DENSITY , A/cm 2 



000 



Fig. 7-13. Specific multimode, muticolor blue-green Ar II output from several different tube diameters plotted vs. 
discharge current density (Ref. 25). 



284 Handbook of Lasers 



2.0 



1.0 — 



0.5 - 



UJ 

o 

g o.l 

o 
a. 



0.05 



0.01 




50 



100 500 

CURRENT DENSITY, A/cm 2 



1000 



Fig. 7-14. Specific multimode, multicolor blue-green Ar II output from 1.2, 2.5 and 4.1 mm diameter tubes described 
in Ref. 93, replotted as P/V vs. J (Ref. 25). 



=> 
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tr. 

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p (mTorr) =240 




7 Ionized Gas Lasers 

480 E746-I8R2 

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400 
320 



285 



D = 4 mm 
L= 71cm 
B= IkG 



560 



ORUN ENDED BY DISCHARGE IN STABILITY 



J I L_L 



10 



50 



100 



DISCHARGE CURRENT. A 

Fig. 7-15. Measured output power as a function of discharge current with cold filling pressure as a parameter, 
showing the curve crossing caused by gas driveout at higher discharge currents. (Ref. 25.) 



286 



Handbook of Lasers 



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DISCHARGE CURRENT, A 



100 



Fig. 7-16. Power output per color for the stronger Ar II lines using an external prism to separate the wavelengths. 
Same tube as Fig. 7-15 with p = 480 mTorr (Ref. 25). 



7 Ionized Gas Lasers 



287 



lower level in Ar II). These two lines compete strongly in a typical cw Kr II ion laser. Evidently their 
lower level is not nearly so well-depleted by radiation as the corresponding Ar II lower level. A simple 
P/V~J 2 behavior would not be expected (and, in fact, is not observed) for Kr II, unless very low gas 
pressures are used to reduce radiation trapping effects. 

Figure 7-17 shows the typical variation with current of the optimum gas filling pressure for argon 
ion lasers of different bore diameters. In all cases the optimum pressure (that is, the gas pressure in 
the tube measured before the discharge is struck) increases with increasing discharge current and with 
decreasing tube diameter. Figure 7-17 is not universal in the sense that discharge tubes of different 
lengths, type of construction (smooth walls, disks, segments, etc.), or tubes with different gas return 
paths* will exhibit somewhat different values. The general trends are as shown in Figure 7-17, however. 



500 



300 I- 



200 



100 



50 



30 



20 




D=8mm 
L=50cm 



J L 



J L 



10 



20 30 40 

DISCHARGE CURRENT, A 



50 



60 



Fig. 7-17. Optimum gas pressure for maximum laser 
output, plotted as a function of discharge current for 
various capillary diameters (Ref. 25). 

Likewise, pulsed operation shows the same trends, but with approximately an order of magnitude 
lower pressure. The heavier noble gases (Kr, Xe) also prefer lower pressures than shown in Figure 7-17, 
both in cw operation and in pulsed operation. Neon pressures are generally similar to argon. 

Figure 7-18 shows the general behavior of the optimum magnetic field for cw argon ion lasers. 
The data are taken from several sources. The optimum magnetic field decreases with increasing tube 
diameter. Again, the curve is not universal, since there is some interaction between gas pressure and 
magnetic field (see Ref. 70 for a further discussion of this interaction). For the heavier noble gases 
(Kr, Xe) the optimum magnetic field generally decreases from the corresponding argon value, and 
becomes more critical; also with Kr and Xe, different transitions may optimize at quite different 
magnetic fields, so that the laser can actually be "color-tuned" with a magnetic field. (In argon, all 
the Ar II lines optimize together.) 

Figure 7-19 gives a typical comparison between the performances obtained with argon and krypton 
in the same lasers. The three curves for argon (3-, 4-, and 5-mm tubes) give the total multimode blue- 
green output in the usual distribution among colors (see Figure 7-16), while the two curves for krypton 
give the output on the red lines 0.6471 and 0.6764 ^m. At the maximum output shown, about 80% of 
the power occurs at 0.6471 /im. The krypton blue-green output is typically less than the red output, 



* See Refs. 25, 37, 38 and 143 for discussions of gas pumping and gas return paths. 



288 Handbook of Lasers 



DECREASING 
PRESSURE 



TUBE DIAMETER, mm 

Fig. 7-18. Optimum magnetic field for maximum laser output, plotted as a function of discharge diameter. (Data 
from refs. as follows: # Ref. 25, ▼ Ref. 93, ■ Ref. 124, A Ref. 67, O Ref. 70.) 



but about a factor of 2-3 less than the blue-green argon output and spread more uniformly among 
the different lines from 0.4619 to 0.5308 /mi. 

Higher Ionization States; Ultraviolet Operation 

Although pulsed laser action on multiply ionized atoms was obtained in 1964 shortly after the 
first ion laser was demonstrated, very little attention was devoted to development of practical devices 
utilizing the higher spectra. CW operation of multiply ionized species was first obtained in 1966 by 
Bridges and Halsted 24 on visible lines in Xe III and shortly thereafter in the ultraviolet by Paananen 110 
on Ar III and Kr III. Since that time, development of practical cw ultraviolet lasers has been under- 
taken by several groups. The highest powers obtainable now exceed 2 W cw, using the Ar III 0.3638 /mi 
line. Figure 7-20 shows the typical output obtained from an Ar III laser. At the maximum current 
shown, about 80% of the output was at 0.3638 /mi, with most of the remainder at 0.3511 /mi and a 
small amount distributed among the triplet 0.3362, 0.3345 and 0.3359 /an. The particular tube used to 
obtain the data shown in Figure 7-20 was a disk structure with an active length of about 50 cm and an 
effective bore diameter of 2.3 mm. (See Ref. 29 for a more complete description.) Figure 7-21 compares 
the cw outputs obtained with argon and krypton in a similar tube structure. Again the argon output 
is about 80% 0.3638 +20% 0.3511 /mi, while the krypton output was about 70% 0.3507 + 30% 
0.3564 /mi. Additional data on a similar tube can be found in the paper by Latimer, Ref. 95. 

In both Figures 7-20 and 7-21 the power appears to be increasing faster than quadratically with 
current at the highest currents used. Based on similar arguments to those given in Ref. 25, one might 
expect a.P/V ~J 3 behavior; however, in the current density regime necessary to give higher ionization 
state operation, several of the assumptions made about the plasma in Ref. 25 are violated. At this time, 
no scaling law analogous to eq. (2) is known. 

A systematic survey of cw ultraviolet and violet lines has been made by Fendley, 53 using a seg- 
mented graphite tube with a 1.7 mm bore diameter and a 34 cm active length. Figures 7-22 through 
7-25 summarize his results for the relative spectral content of Ne, Ar, Kr, and Xe lasers, while Figures 
7-26 through 7-29 give specific power and gains for several of the most powerful transitions. 



7 Ionized Gas Lasers 289 



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DISCHARGE CURRENT, A 



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Fig. 7-19. Comparison between Ar II blue-green and Kr II red (.6471 + .6764 /xm) outputs for typical ion lasers. 
All tubes had 46 cm active lengths. Gas pressure and magnetic field were optimized at the highest power shown (Hughes 
Research Laboratories data). 



290 



Handbook of Lasers 



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D = 2.3mm 
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Ref. 29). 



7 Ionized Gas Lasers 



291 



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Fig. 7-21. Comparison of Ar III and Kr III ultraviolet outputs. (Rcf. 29.) 



292 



Handbook of Lasers 



100 
mw 
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20 

10 

5 



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P 



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3713 
8 



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Ne nr 

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44 



Fig. 7-22. Distribution of Ne II ultraviolet output 
powers from a small bore ion laser (Ref. 53). 



100 

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10- 
5- 

2- 



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P 



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3345 \ 
3358 J 



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36 



38 



40 



42 



Fig. 7-23. Distribution of Ar III ultraviolet output 
powers from a small bore ion laser (Ref. 53). 



100 
mW 
50 

20 
10 - 
5 - 



3507 
P 



3375 
I 



32mti 34 



3564 



4067 
B 



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20 A 


1 200 G 


35 TORR 



36 



38 



40 




42 



Fig. 7-24. Distribution of Kr III ultraviolet output 
powers from a small bore ion laser (Ref. 53). 



7 Ionized Gas Lasers 



293 



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50 






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240 V 












18 A 
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Fig. 7-25. Distribution of Xe III ultraviolet output 
powers from a small bore ion laser (Ref. 53). 





NeTT # 




• 3324 A / 




o • 




O 3378 A / f 




• P 


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Fig. 7-26. Small-signal gain coefficient and output power for uv lines in Ne II 
as a function of discharge current (Ref. 53). 



5 - 



Ar HE 

o 3638 A 

A 35 II A 
D 3336 A 



05 



1200 G 
33T0RR 



2A/mm 2 



id 

o I 

If 

A D 
/ 



MM 



10 



mW 
cm 



Po 



1.7 mm 
BORE DIA. 



2 - 



2A/mm 2 



/ 

OA 

il 

![ 

i 

A 



1 I I I 



10 



Fig. 7-27. Small-signal gain coefficient and output power for uv lines in Ar III 
as a function of discharge current (Ref. 53). 



294 



Handbook of Lasers 



< 


i 




5 


- 




■T 1 


Kr m 
• 3507A 








• 




— o 3564A 


/ 

• 

/ 

• 


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/ 




1200 G 
" 35 TORR 






.' /" 


.1 




/ i° 




— 


• / 

/ ° 






i 1 






o 


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1 1 


1 1 1 1 1 1 „ 



10- 



Po 




I. 7 m m 
BORE DIA 



2A/r 



10 



2A/mm 2 



10 



Fig. 7-28. Small-signal gain coefficient and output power for uv lines in Kr HI 
as a function of discharge current (Ref. 53). 



5 — 



05 



Xe HE 



V 378IA 
1000 G 
22 TORR 



o 4214 A 

— IIOOG 

— 27 TORR 



/ 



/ 



/ 



2 A /mm 2 



20' 
mW 


X 




V 

o 


cm 




4214 A ► 


/' 


10 


— 




o 

/ 

o 


Po 
5 


— 


1.7mm 
BORE DIA 

3781 A — » 


I 

1 

V 

/ 








? 




1 1 M 


1 

'1 MIL 



10 



2A/mm 2 



Fig. 7-29. Small-signal gain coefficient and output power for uv lines in Xe III 
as a function of discharge current (Ref. 53). 



REFERENCES 

1. R. der Agobian, J.-L. Otto, R. Cagnard, J. Barthelemy, and R. Echard, "Emission stimulee en regime permanent dans le 
spectra visible du krypton ionise," Compt. Rend., 260, 6327-6329, 1965. 

2. V. S. Aleinikov, "Use of an electron gun to determine the nature of collisions of the second kind in a mercury-helium 
mixture," Opt. Spectry. (USSR), 28, 15-17, 1970. 

3. R. B. Allen, R. B. Starnes, and A. A. Dougal, "A new pulsed ion laser transition in nitrogen at 3995 A," IEEE J. Quant. 
Electronics, QE-2, 334, 1966. 

4. O. Andrade, M. Gallardo, and K. Bockasten, "High-gain laser lines in noble gases," Appl. Phys. Lett., 11, 99-100, 1967. 

5. K. Banse, G. Herziger, G. Schaefer, and W. Seelig, "Continuous U.V.-laser power in the watt range," Phys. Lett., 27 A, 
682-683, 1968. 

6. W. E. Bell, "Visible laser transitions in Hg + ," Appl. Phys. Lett., 4, 34-35, 1964. 

7. W. E. Bell, "Ring discharge excitation of gas ion lasers," Appl. Phys. Lett., 7, 190-191, 1965. 

8. W. E. Bell, A. L. Bloom, and J. P. Goldsborough, "Visible laser transitions in ionized selenium, arsenic, and bromine," 
IEEE J. Quant. Electronics, QE-1, 400, 1965. 

9. W. E. Bell, A. L. Bloom, and J. P. Goldsborough, "New laser transitions in antimony and tellurium," IEEE J. Quant. 
Electronics, QE-2, 154, 1966. 

10. W. E. Bell, private communication. 

11. W. R. Bennett, Jr., J. W. Knutson, Jr., G. N. Mercer, and J. L. Detch, "Super-radiance, excitation mechanisms, and 
quasi-cw oscillation in the visible Ar + laser," Appl. Phys. Lett., 4, 180-182, 1964. 

12. M. Birnbaum and T. L. Stocker, private communication, 1965. 



7 Ionized Gas Lasers 295 

13. A. L. Bloom, W. E. Bell, and F. O. Lopez, "Laser spectroscopy of a pulsed mercury-helium discharge," Phys. Rev., 135, 
A578-A579, 1964. 

14. A. L. Bloom and J. P. Goldsborough, "New CW laser transitions in cadmium and zinc ion," IEEE J. Quant. Electronics, 
QE-6, 164, 1970. 

15. A. L. Bloom, private communication, 9 May 1968. 

16. A. L. Bloom, private communication, 21 December 1964. 

17. M. Birnbaum, A. W. Tucker, J. A. Gelbwachs, and C. L. Fincher, "New O II laser line (6640 A)," IEEE J. Quant. Elec- 
tronics, QE-7, 208, 1971. 

18. K. Bockasten, M. Garavaglia, B. A. Lengyel, and T. Lundholm, "Laser lines in Hg I," J. Opt. Soc. Am., 55, 1051-1053, 
1965. 

19. K. Bockasten, T. Lundholm, and O. Andrede, "New near infrared laser lines in Argon I," Phys. Lett., 22, 145-146, 1966. 

20. W. B. Bridges, "Laser oscillation in singly ionized argon in the visible spectrum," Appl. Phys. Lett., 4, 128-130, 1964; 
erratum: Appl. Phys. Lett., 5, 39, 1964. 

21. W. B. Bridges, "Laser action in singly ionized krypton and xenon," Proc. IEEE, 52, 843-844, 1964. 

22. W. B. Bridges and A. N. Chester, "Visible and uv laser oscillation at 1 18 wavelengths in ionized neon, argon, krypton, xenon, 
oxygen, and other gases," Appl. Opt., 4, 573-580, 1965. 

23. W. B. Bridges and A. N. Chester, "Spectroscopy of ion lasers," IEEE J. Quant. Electronics, QE-1, 66-84, 1965. 

24. W. B. Bridges and A. S. Halsted, "New CW laser transitions in argon, krypton, and xenon," IEEE J. Quant. Electronics, 
QE-2, 84, 1966. 

25. W. B. Bridges and A. S. Halsted, "Gaseous ion laser research," Technical Report No. AFAL-TR-67-89, Hughes Research 
Laboratories, Malibu, California, May 1967 (DDC No. AD-814897). 

26. W. B. Bridges, R. J. Freiberg, and A. S. Halsted, "New continuous UV ion laser transitions in neon, argon, and krypton," 
IEEE J. Quant. Electronics, QE-3, 339, 1967. 

27. W. B. Bridges and A. N. Chestei, unpublished data, January 1965. 

28. W. B. Bridges and G. N. Mercer, "CW operation of high ionization states in a xenon laser," IEEE J. Quant. Electronics, 
QE-5, 416-411, 1969. 

29. W. B. Bridges and G. N. Mercer, "Ultraviolet ion laser," Technical Report No. ECOM-0229-F, Hughes Research La- 
boratories, Malibu, California, October 1969 (DDC No. AD-861927). 

30. W. B. Bridges and A. N. Chester, unpublished data, 1969 and 1970. 

31. W. B. Bridges, P. O. Clark, and A. S. Halsted, "High power gas laser research," Technical Report No. AFAL-TR-66-369, 
Hughes Research Laboratories, Malibu, California, January 1967 (DDC No. AD-807363). 

32. R. L. Byer, W. E. Bell, E. Hodges, and A. L. Bloom, "Laser emission in ionized mercury: isotope shift, linewidth, and 
precise wavelength,"/. Opt. Soc. Am., 55, 1598-1602, 1965. 

33. W. C. Carr and R. W. Grow, "Silicon and chlorine laser oscillations in SiCl 4 ," Proc. IEEE, 55, 726, 1967. 

34. W. C. Carr and R. W. Grow, "A new laser line in tin using stannic chloride vapor," Proc. IEEE, 55, 1 198, 1967. 

35. P. K. Cheo and H. G. Cooper, "Ultraviolet ion laser transitions between 2300 and 4000 A," J. Appl. Phys., 36, 1862-1865, 
1965. 

36. P. K. Cheo and H. G. Cooper, "UV and visible laser oscillations in fluorine, phosphorus, and chlorine," Appl. Phvs. Lett., 
7, 202-204, 1965. Corrections: see H. P. Palenius (Ref. 111). 

37. A. N. Chester, "Gas pumping in discharge tubes," Phys. Rev., 169, 172-184, 1968. 

38. A. N. Chester, "Experimental measurements of gas pumping in an argon discharge," Phys. Rev., 169, 184-193, 1968. 

39. D. M. Clunie, private communication, 2 May 1966. 

40. G. Convert, M. Armand, and P. Martinot-Lagarde, "Effet laser dans des melanges mercure-gaz rares," Compt. Rend., 
258, 3259-3260, 1964. 

41. G. Convert, M. Armand, and P. Martinot-Lagarde, "Transitions laser visibles dans l'argon ionise," Compt. Rend., 258, 
4467-4469, 1964. 

42. H. G. Cooper and P. K. Cheo, "Laser transitions in B II, Br II, and Sn," IEEE J. Quant. Electronics, QE-2, 785, 1966. 

43. H. G. Cooper and P. K. Cheo, "Ion laser oscillations in sulfur," in " Physics of Quantum Electronics," Ed. by P. L. Kelley, 
B. Lax, and P. E. Tannenwald, pp. 690-697 (McGraw-Hill, New York, 1966). 

44. T. H. E. Cottrell, D. C. Sinclair, and J. M. Forsyth, "New laser wavelengths in krypton," IEEE J. Quant. Electronics, 
QE-2, 703, 1966. 

45. J. A. Dahlquist, "New lines in a pulsed xenon laser," Appl. Phys. Lett., 6, 193-194, 1965. 

46. L. Dana, P. Laures, and R. Rocherolles, "Raies laser ultraviolettes dans le neon, l'argon et le xenon," Compt. Rend., 260, 
481-484, 1965. 

47. L. Dana and P. Laures, "Stimulated emission in krypton and xenon ions by collisions with metastable atoms," Proc. IEEE, 
53, 78-79, 1965. 

48. J. S. Deech and J. H. Sanders, "New self-terminating laser transitions in calcium and strontium," IEEE J. Quant. Elec- 
tronics, QE-4, 474, 1968. 

49. W. Demtroder, "Excitation mechanisms of pulsed argon ion lasers at 4880 A," Phys. Lett., 22, 436-438, 1966. 

50. R. der Agobian, see Ref. 1. 

51. D. J. Dyson, "Mechanism of population inversion at 6149 A in the mercury ion laser," Nature, 207, 361-363, 1965. 

52. K. G. Ericsson and L. R. Lidholt, "Superradiant transitions in argon, krypton, and xenon," IEEE J. Quant. Electronics, 
QE-3, 94, 1967. 

53. J. R. Fendley, Jr., "Continuous UV lasers," IEEE J. Quant. Electronics, QE-4, 627-631, 1968. 

54. G. R. Fowles and R. C. Jensen, "Visible laser transitions in the spectrum of singly ionized iodine," Proc. IEEE, 52, 851- 
852, 1964. 

55. G. R. Fowles and R. C. Jensen, "Visible laser transitions in ionized iodine," Appl. Opt., 3, 1 191-1 192, 1964. 

56. G. R. Fowles and W. T. Silfvast, "Laser action in the ionic spectra of zinc and cadmium," IEEE J. Quant. Electronics, 
QE-1, 131, 1965. 

57. G. R. Fowles, W. T. Silfvast, and R. C. Jensen, "Laser action in ionized sulfur and phosphorus," IEEE J. Quant. Elec- 
tronics, QE-1, 183-184, 1965. 

58. G. R. Fowles and B. D. Hopkins, "CW laser oscillation at 4416 A in cadmium," IEEE J. Quant. Electronics, QE-3, 419, 
1967. 

59. G. R. Fowles and R. C. Jensen, "Laser oscillation on a single hyperfine transition in iodine," Phys. Rev. Lett., 14, 347- 
348, 1965. 

60. M. Gallardo, M. Garavaglia, A. A. Tagliaferri, and E. Gallego Lleusma, "About unidentified ionized Xe laser lines," IEEE 
J. Quant. Electronics, QE-6, 745-747, 1970. 

61. H. J. Gerritsen and P. V. Goedertier, "Blue gas laser using Hg 2+ ", J. Appl. Phys., 35, 3060-3061, 1964. 

62. H. J. Gerritsen, private communication, 11 January 1965. 



296 Handbook of Lasers 

63. J. P. Goldsborough and A. L. Bloom, "New CW ion laser oscillation in microwave-excited xenon," IEEE J. Quant. Elec- 
tronics, QE-3, 96, 1967. 

64. J. P. Goldsborough, "Continuous laser oscillation at 3250 A in cadmium ion," IEEE J. Quant. Electronics, QE-5, 133, 1969. 

65. J. P. Goldsborough and E. B. Hodges, "Stable, long-life operation of helium-cadmium lasers at 4416 A and 3250 A," 
IEEE J. Quant. Electronics, QE-5, 361-362, 1969. 

66. J. P. Goldsborough and A. L. Bloom, "Near-infrared operating characteristics of the mercury ion laser," IEEE J. Quant. 
Electronics, QE-5, 459-460, 1969. 

67. J. P. Goldsborough, E. B. Hodges, and W. E. Bell, "Rf induction excitation of cw visible laser transitions in ionized gases," 
Appl. Phys. Lett., 8, 137-139, 1966. 

68. E. I. Gordon, E. F. Labuda, and W. B. Bridges, "Continuous visible laser action in singly ionized argon, krypton, and 
xenon," Appl. Phys. Lett., 4, 178-180, 1964. 

69. E. I. Gordon, E. F. Labuda, R. C. Miller, and C. E. Webb, "Excitation mechanisms of the argon ion laser," in "Physics 
of Quantum Electronics," Ed. by P. L. Kelley, B. Lax, and P. E. Tannenwald, pp. 664-673 (McGraw-Hill, New York, 
1966). 

70. I. Gorog and F. W. Spong, "High pressure, high magnetic field effects in continuous argon ion lasers," Appl. Phys. Lett., 
9, 61-63, 1966. 

71. A. S. Halsted, W. B. Bridges, and G. N. Mercer, "Gaseous ion laser research," Technical Report No. AFAL-TR-68-227, 
Hughes Research Laboratories, Malibu, California, July 1968. (DDC No. AD-841834). 

72. S. Hattori and T. Goto, "A flash lamp with toroidal discharge excitation," Jap. J. Appl. Phys. 6, 356-363, 1967. 

73. H. G. Heard, G. Makhov, and J. Peterson, "Laser action in mercury rare gas mixtures," Proc. IEEE, 52, 414, 1964. 

74. H. G. Heard and J. Peterson, "Mercury-rare gas visible-UV laser," Proc. IEEE, 52, 1049-1050, 1964. 

75. H. G. Heard and J. Peterson, "Orange through blue-green transitions in a pulsed-CW xenon gas laser," Proc. IEEE, 52, 
1050, 1964. 

76. H. G. Heard and J. Peterson, "Visible laser transitions in ionized oxygen, nitrogen, and carbon monoxide," Proc. IEEE, 
52, 1258, 1964. 

77. D. T. Hodges, "Helium-cadmium laser parameters," Appl. Phys. Lett., 17, 11-13, 1970; erratum: Apply. Phys. Lett., 18, 
362, 1971. 

78. F. A. Horrigan, S. H. Koozekanani, and R. A. Paananen, "Infrared laser action and lifetimes in argon II," Appl. Phys. 
Lett., 6, 41-43, 1965. 

79. S. M. Jarrett and G. C. Barker, "High-power output at 5353 A from a pulsed xenon ion laser," IEEE J. Quant. Electronics, 
QE-5, 166, 1969. 

80. R. C. Jensen and G. R. Fowles, "New laser transitions in iodine-inert gas mixtures," Proc. IEEE, 52, 1350, 1964. 

81. R. C. Jensen and W. R. Bennett, Jr., "Role of charge exchange in the zinc ion laser," IEEE J. Quant. Electronics, QE-4, 
356, 1968. 

82. R. C. Jensen, G. J. Collins, and W. R. Bennett, Jr., "Charge-exchange excitation and cw oscillation in the zinc-ion laser," 
Phys. Rev. Lett., 23, 363-367, 1969. 

83. A. M. Johnson and C. E. Webb, "New CW laser wavelength in Kr II," IEEE J. Quant. Electronics, QE-3, 369, 1967. 

84. E. K. Karabut, V. S. Mikhalevskii, V. F. Papakin, and M. F. Sem," Continuous generation of coherent radiation in a dis- 
charge in Zn and Cd vapors obtained by cathode sputtering," Sov. Phys.-Tech. Phys., 14, 1447-1448, 1970. 

85. W. M. Keeffe and W. J. Graham, "Laser oscillation in the visible spectrum of singly ionized pure bromine vapor," Appl. 
Phys. Lett., 7, 263-264, 1965. 

86. W. M. Keeffe and W. J. Graham, "Observation of new Br II laser transitions," Phys. Lett., 20, 643, 1966. 

87. V. F. Keydan and V. S. Mikhalevskii, "Pulsed generation in bismuth vapor," Zh. Prikl. Spektrosk., 9, 713, 1968. 

88. M. B. Klein, "Time-resolved temperature measurements in the pulsed argon ion laser," Appl. Phys. Lett., 17, 29-32, 1970. 

89. S. Kobayashi, T. Izawa, K. Kawamura, and M. Kamiyama, "Characteristics of a pulsed Ar II ion laser using the external 
spark gap," IEEE J. Quant. Electronics, QE-2, 699-700, 1966. 

90. V. M. Koval'chuk and G. G. Petrash, "New generation lines of a pulsed iodine-vapor laser," J ETP Lett., 4, 144-146, 1966. 

91. S. G. Kulagin, V. M. Likhachev, E. V. Markuzon, M. S., Rabinovich, and V. M. Sutovskii, "States with population in- 
version in a self-compressed discharge," J ETP Lett., 3, 6-8, 1966. 

92. E. F. Labuda and A. M. Johnson, "Threshold properties of continuous duty rare gas ion laser transitions," IEEE J. Quant. 
Electronics, QE-2, 700-70-1, 1966. 

93. E. F. Labuda, E. I. Gordon, and R. C. Miller, "Continuous-duty argon ion lasers," IEEE J. Quant. Electronics, QE-1, 
273-279, 1965. 

94. E. F. Labuda, C. E. Webb, R. C. Miller, and E. I. Gordon, "A study of capillary discharges in noble gases at high current 
densities," presented at the 18th Gaseous Electronics Conference, Minneapolis, Minnesota, October 1965. 

95. I. D. Latimer, "High power quasi-CW ultraviolet ion laser," Appl. Phys. Lett., 13, 333-335, 1968. 

96. P. Laures, L. Dana, and C. Frapard, "Nouvelles transitions laser dans le domaine 0.43-0.52 fi obtenues a partir du spectre 
du krypton ionise," Compt. Rend., 258, 6363-6365, 1964. 

97. P. Laures, L. Dana, and C. Frapard, "Nouvelles raies laser visibles dans le xenon ionise," Compt. Rend., 259, 745-747, 1964. 

98. R. K. Leonov, E. D. Protsenko, and Yu. M. Sapunov, "Some results of a study of the pulsed argon laser," Opt. Spectry. 
(USSR), 21, 141-142, 1966. 

99. G. R. Levinson, V. F. Papulovskiy, and V. P. Tychinskiy, "The mechanism of inversion of the populations of the various 
levels in multivalent argon ions," Rad. Ena. Electr. Phys., 13, 578-582, 1968. 

100. H. S. W. Massey and E. H. S. Burhop, "Electronic and ionic impact phenomena," Oxford, 1952, p. 165. 

101. R. A. McFarlane, "Laser oscillation on visible and ultraviolet transitions of singly and multiply ionized oxygen, carbon, 
and nitrogen," Appl. Phys. Lett., 5, 91-93, 1964. 

102. R. A. McFarlane, "Optical maser oscillation on iso-electronic transitions in Ar III and CI II," Appl. Opt., 3, 1196, 1964. 

103. R. A. McFarlane, private communication, 1 December 1964. 

104. R. C. Miller, E. F. Labuda, and E. I. Gordon, paper presented at the Conference on Electron Device Research, Cornell 
University, Ithaca, N.Y., June 1964. 

105. R. H. Neusel, "A new xenon laser oscillation at 5401 A," IEEE J. Quant. Electronics, QE-2, 70, 1966. 

106. R. H. Neusel, "A new krypton laser oscillation at 5016.4 A," IEEE J. Quant. Electronics, QE-2, 106, 1966. 

107. R. H. Neusel, "New laser oscillations in krypton and xenon," IEEE J. Quant. Electronics, QE-2, 334, 1966. 

108. R. H. Neusel, "New laser oscillations in xenon and krypton," IEEE J. Quant. Electronics, QE-2, 758, 1966. 

109. R. H. Neusel, "New laser oscillations in Ar, Kr, Xe, and N," IEEE J. Quant. Electronics, QE-3, 207-208, 1967. 

110. R. Paananen, "Continuously-operated ultraviolet lasers," Appl. Phys. Lett., 9, 34-35, 1966. 

111. H. P. Palenius, "The identification of some Si and CI laser lines observed by Cheo and Cooper," Appl. Phys. Lett., 8, 82- 
83, 1966. 

112. A. Papayoanou and I. Gumeiner, "High power xenon laser action in high current pinched discharges," Appl. Phys. Lett., 
16, 5-8, 1970. 



7 Ionized Gas Lasers 297 

113. R. I. Rudko and C. L. Tang, "Excitation mechanisms in the Ar II laser," Appl Phys. Lett 9 41-44, 1966. 

114. W. K. Schuebel, "New cw Cd-vapor laser transitions in a hollow-cathode structure, Appl Phys Lett 16 4 l°~^ 12 ' ™ 70 ; 

115. W. T. Silfvast, G. R. Fowles, and B. D. Hopkins, "Laser action in singly ionized Ge, Sn, Pb, In, Cd, and Z.n, Appl. rnys. 

116. W. T. Silfvast, "Efficient cw laser oscillation at 4416 A in Cd (II)," Appl. Phys. Lett., 13, 169-171 1968. 

117 W T. Silfvast, "New cw metal-vapor laser transitions in Cd, Sn, and Zn," Appl. Phys. Lett., 15, 23-25, 1969. 

118. V. A. Tolkachev, "Super-radiant transitions in Ar and Kr," Zh. Prikl. Spektrosk 8 746-749 May 1968 

1 19. W. T. Silfvast, and M. B. Klein, "CW laser action on 24 visible wavelengths in Se II, Appl. Phys. Lett., 17, 400-403, 197U. 

120. W. T. Silfvast, private communication, 21 May 1971. 

121. W. W. Simmons and R. S. Witte, "High-power pulsed xenon ion lasers," IEEE J. Quant. Electronics, QE-6, 466-469, I97U. 

122. W. W. Simmons, private communication, 29 July 1970. 

123. D. C. Sinclair, "Near-infrared oscillation in pulsed noble-gas-ion lasers," /. Opt. Soc. Am., 55, 571-572, 1965. 

124 D. C. Sinclair, "Polarization characteristics of an ionized-gas laser in a magnetic field," J. Opt. Soc. Am., 56, 1727, 1966. 

125. Y. Sugawara and Y. Tokiwa, "CW laser oscillations in Zn II and Cd II in hollow cathode discharge," Jap. J. Appl. Phys., 
9, 588-589, May 1970. . 

126. Y. Sugawara and Y. Tokiwa, "CW hollow cathode laser oscillations in Zn + and Cd + ," Technology Reports ot the Seikei 
University, No. 9, pp. 759-760, March, 1970. . 

127. Y. Sugawara, Y. Tokiwa, and T. Iijima, "Excitation mechanisms of cw laser oscillations in Zn II and Cd 11 in hollow 
cathode discharges," Paper 16.6, Sixth International Quantum Electronics Conference, Sept. 7-10, 1970, Kyoto, Japan. 

128. N. Suzuki, "Spectroscopy of mercury-helium discharge and 61 50 A laser oscillation," Jap. J. Appl. Phys., 4, 452-457, 1965. 

129. B. Tell, R. J. Martin, and D. MacNair, "CW laser oscillation in ionized xenon at 9697 A," IEEE J. Quant. Electronics, » 
QE-3, 96, 1967. 

130. A. S. Tibiloz, "Generation of radiation in He-Cd and Ne-Cd mixtures," Opt. Spectry. (USSR) 19, 463-464, 1965. 

131. W. T. Walter, N. Solimene, M. Piltch, and G. Gould, "Efficient pulsed gas discharge lasers," IEEE J. Quant. Electronics, 
QE-2, A1A-A19, 1966. 

132. C. E. Webb, "New pulsed laser transitions in Te II," IEEE J. Quant. Electronics, QE-4, 426-427, 1968. 

133. C. S. Willett and O. S. Heavens, "Laser transition at 651.6 nm in ionized iodine," Opt. Acta, 13, 271-274, 1966. 

134. C. S. Willett, "New laser oscillations in singly ionized iodine," IEEE J. Quant. Electronics, QE-3, 33, 1967. 

135. C. S. Willett and O. S. Heavens, "Laser oscillation on hyperfine transitions in ionized iodine," Opt. Acta, 14, 195-197, 1967. 

136. C. S. Willett, "Note on near-infrared operating characteristics of the mercury ion laser," IEEE J. Quant. Electronics, 
QE-6, 469-471, 1970. 

137. C. B. Zarowin, "New visible CW laser lines in singly-ionized chlorine," Appl. Phys. Lett., 9, 241-242, 1966. 

138. J. P. Goldsborough, "Stable, long-life cw excitation of helium-cadmium lasers by dc cataphoresis," Appl. Phys. Lett., 15, 
159-161, 1969. 

139. D. T. Hodges and C. L. Tang, "New cw ion laser transitions in argon, krypton and xenon," IEEE J. Quant. Electronics, 
QE-6, 757-758, 1970. 

140. V. Hoffmann and P. Toschek, "New laser emission from ionized xenon," IEEE J. Quant. Electronics, QE-6. 757, 1970. 

141. J. P. Wheeler, "A new xenon laser line observed," IEEE J. Quant. Electronics (to be published Aug., 1971). 

142. V. F. Kitaeva, A. N. Odintsov, and N. N. Sobolev, "Continuously operating argon ion lasers," Soviet Physics — Uspekhi, 12, 
699-730, 1970. 

143. W. B. Bridges, A. N. Chester, A. S. Halsted, and J. V. Parker, "Ion laser plasmas," Proc. IEEE, 59, 724-737, 1971. 

144. W. K. Schuebel, "Continuous visible and near-infrared laser action in Hg. II," IEEE J. Quant. Electronics, QE-7, 39-40 
1971. 

NOTE ADDED IN PROOF 

Some additions and changes came to our attention too late to be included in the present chapter. Twenty-two additional wave- 
lengths have been observed in ionized selenium between 0.4467 and 1.26 /xm by Klein and Silfvast (Ref, 145). Hodges has ob- 
served 4 cw lines in singly-ionized magnesium in the range 0.9218 to 1.0952 pm (Ref. 146). Pulsed oscillation has been obtained 
on two infrared ion lines in singly-ionized ytterbium (1.6498 and 2.4377 /xm) (Ref. 147) and two in singly-ionized barium (2.5924 
and 2.9057 pm) (Ref. 148) by Cahuzac. Additional information on the excitation mechanisms of the He-Zn ion laser has been 
reported by Riseberg and Schearer (Ref. 149). A complete remeasurement of the spontaneous spectrum As II by Li and Andrew 
(Ref. 150) contains more accurate wavelengths and a reclassification of the levels for the four arsenic ion lines in Table 7.5.3. 

145. M. B. Klein and W. T. Silfvast, "New cw laser transitions in Se II," Appl. Phys. Lett, (to be published June 1971). 

146. D. T. Hodges, "CW laser oscillation in singly ionized magnesium," Appl. Phys. Lett, (to be published May 1971). 

147. Ph. Cahuzac, "Emissions laser infrarouges dans les vapeurs de terres rares," Phys. Lett., 31 A, 541-542, 1970. 

148. Ph. Cahuzac, "Nouvelles raies laser infrarouges dans la vapeur de baryum," Phys. Lett. 32A, 150-151, 1970. 

149. L. A. Riseberg and L. D. Schearer, "On the excitation mechanism of the He-Zn laser," IEEE J. Quant. Electronics, QE-7, 
40-41, 1971. 

150. H. Li and K. L. Andrew, "First spark spectrum of arsenic," /. Opt. Soc. Am., 61, 96-109, 1971. 



Molecular Gas Lasers 



Martin A. Pollack 

Bell Telephone Laboratories 
Holmdel, New Jersey 07733 

MOLECULAR LASER SOURCE MATERIALS 

Molecular gas lasers have been operated using a variety of excitation methods, including electrical, 
optical and chemical pumping. In some pumping methods, a mixture of gases is added to the laser gas 
to modify relaxation rates and gas cooling, or to provide collisional energy transfer. An example of 
this is the addition of He and N 2 to C0 2 gas lasers. 



TABLE 8-1. MOLECULAR LASER SOURCE MATERIALS 


Starting 


See 


Laser 


Starting 


See 


Laser 


material 


section 


molecule 


material 


section 


molecule 


BBr 3 


8.2.3b 


HBr 


D 2 


8.2.6 


D 2 ,HD 


BC1 3 


8.2.4b 


HC1 




8.2.3c 


DBr 


BF 3 


8.2.5b 


HF 




8.2.4c 


DC1 


BrCN 


8.3.3b 


DCN 




8.2.5c 


DF 


Br 2 


8.2.3a 


HBr 




8.3.3.b 


DCN 


CBrF 3 


8.2.5a,b 


HF 


D 2 


8.3.4c 


D 2 




8.2.5c 


DF 


F 2 


8.2.5a 


HF 


CCIF3 


8.2.4b 


HC1 


HCN 


8.3.3a 


HCN 




8.2.5a,b 


HF 




8.3.3c 


HCN 15 




8.2.5c 


DF 


HI 


8.2.4a 


HC1 


CC1 2 F 2 


8.2.5a,b 


HF 


H 2 


8.2.3a 


HBr 




8.2.5c 


DF 




8.2.4a,b 


HC1 


CCI3F 


8.2.5b 


HF 




8.2.5a,b 


HF 


CD 4 


8.3.3b 


DCN 




8.2.6a-c 


H 2 


CF* 


8.2.5a 
8.2.5c 


HF 
DF 


H 2 C : CHC1 


8.4.3 


H 2 C : CHC1 








H 2 


8.2.3b 


HBr 


CH 3 Br 


8.2.4b 


HC1 




8.2.4b 


HC1 


CH 3 CN 


8.3.3a 


HCN 




8.2.5b 


HF 


CH 3 C1 


8.2.4b 


HC1 




8.3.4a 


H 2 




8.2.5a 


HF 




8.3.4b 


H 2 18 


CH 3 F 


8.4.1 


CH 3 F 














H 2 S 


8.3.5 


H 2 S 


CH 4 


8.2.5a 


HF 


ICN 


8.3.3a 


HCN? 




8.3.3a 


HCN 


ND 3 


8.3.3b 


DCN 


(CH 3 ) 2 NH 


8.3.3a 


HCN 


NH 3 


8.4.4 


NH 3 


CH 3 OH 


8.4.2 


CH 3 OH 




8.3.3a 


HCN 


CN 


8.2.1 


CN 














NOC1 


8.2.7 


NO 


C 2 N 2 


8.2.1 


CN 


N 2 


8.2.8a-e 


N 2 


CO 


8.2.2a,b 


CO 




8.2.5a 


HF 


co 2 


8.3.1a-i 


co 2 


N 2 


8.3.6a,b 


N 2 


cs 2 


8.2.2a 
8.3.2 


CO 

cs 2 


o 2 


8.2.2a 


CO 








so 2 


8.3.8 


so 2 


Cl 2 


8.2.4a 


HC1 


SF 6 


8.2.5a 


HF 




8.2.4b 


HC1 


UF 6 


8.2.5a 


HF 




8.2.4c 


DC1 




8.2.5c 


DF 



298 



8 Molecular Gas Lasers 299 

Frequently, the excited laser molecule itself is produced in the discharge or reaction tube as a 
result of excitation of one or more different molecules. The reaction of CS 2 and 2 , excited by either 
flash photolysis or an electric discharge, to produce excited CO molecules in the CO laser is represen- 
tative of this case. 

Table 8.1 lists the various materials used in molecular gas lasers along with the resulting laser 
molecules and the sections of Tables 8.2 through 8.4 in which details of these lasers can be found. 
Wavelengths, frequencies (in cm -1 ), transition assignments and other details of operation are also 
given in the individual sections. 

DIATOMIC MOLECULAR GAS LASERS 

Notation for Diatomic Molecular Gas Lasers 

VIBRATIONAL STATE ENERGY (in cm" 1 ): 

G(v) = co e (v + 1/2) - o e X e (v + 111) 2 + • • • 

where co e and X e are the vibrational constants and v is the vibrational quantum number. The 
value of v is also used to index the vibrational states. 
ROTATIONAL LEVEL ENERGY (in cm -1 ): 

F V (J) = B V J{J + 1) - D V J\J + l) 2 + • • • 

where J is the rotational quantum number, and B v and D v are the rotational constants for vibra- 
tional state v. The value of J is also used to index the rotational levels. 
TOTAL ENERGY: 

E = E elec + G(v)+F v (J), 
where E eiec is the energy of the electronic state. 
TRANSITION FREQUENCY: 

v(in cm" 1 ) = E upp „ - E lov/eT . 

Transitions and levels are all in the electronic ground state (E elec = 0) unless otherwise noted. 

Pure Rotational Transitions: involve only a change in J within a given electronic state and within 

a given vibrational state v. The notation adopted here for a transition from an upper rotational 

level J + 1 to lower level J is R(J). 

Vibrational-rotational transitions: involve a change in J and v within a given electronic state. 

The selection rules are Ay = ±1, AJ = 0, ±1 (AJ = is forbidden, unless the number of 

electrons is odd). 
Q BRANCH: A transition from a rotational level J in the upper vibrational state to rotational 
level J in the lower vibrational state is denoted Q(J). Such transitions (with AJ = 0) form the 
Q branch. 

P BRANCH: The P branch is formed of transitions from rotational levels J — 1 in the upper 
vibrational state to levels J in the lower vibrational state, and are denoted P(J). 
R BRANCH: The R branch is formed of transitions from rotational levels J + 1 in the upper 
vibrational state to levels J in the lower vibrational state, and are denoted R(J). 
VIBRATIONAL-ROTATIONAL BAND: TheP, Q and R branch associated with upper vibrational 
state y upper and lower vibrational state tfi ower . The band is denoted by (y upper — Ui owe r)- 
ELECTRONIC SYSTEM: The vibrational-rotational bands associated with transitions between 
two electronic states. The system is denoted by the symbols for the electronic states. Transitions 
are in the ground electronic state when no state or system is given. 

An Example of a Diatomic Molecular Gas Laser: CO 

The CO gas laser is one of the most important diatomic molecular systems. It is capable of pro- 
ducing high continuous or pulsed power levels, and has many properties that are characteristic of the 
entire class of diatomic gas lasers. A partial energy level diagram of CO is given in Figure 8-1. This 



300 



Handbook of Lasers 



shows the electronic laser transitions belonging to the Angstrom band, as well as the vibrational- 
rotational laser transitions belonging to the X"L + ground electronic state. 

The electronic transitions, in the visible region of the spectrum, have only been obtained using 
pulsed electric discharges. The infrared vibrational-rotational transitions, however, have been obtained 
under both pulsed and continuous excitation. Typically, direct excitation by electron impact is pro- 
duced in electric discharges. Chemical reactions have also been used to excite CO lasers. Section 8.2.2 
gives the observed wavelengths and frequencies (in wave number units) of the CO laser transitions, as 
well as some details of the excitation conditions. 



LASER 6080 A 
(ANGSTROM BAND) 



>- ^ 

(r. 4 

z 

UJ -2 



I 




HERZBERG BAND 



2068 A 
(PART OF 4 th 
POS. GROUP) 



LASER ACTION 
(5.03//.-5.38u) 
ON VIBRATIONAL- 
ROTATIONAL 
TRANSITIONS 



2 = OFX'E* 



x'ZV=o CO GROUND STATE 

Fig. 8-1. Partial energy level diagram of CO, showing 
the electronic laser transitions belonging to the Angstrom 
band, and vibrational-rotational laser transitions belonging to 
the Jf 1 E + ground electronic state. (Rotational levels have 
been left out for simplicity.) (Ref. 74) 



Pulsed diatomic molecular lasers typically exhibit cascading of population from one vibrational 
state to the next. This often causes vibrational-rotational bands to appear successively in time. The 
effects of cascading on the power output of an electrically pulsed CO laser are shown in Figure 8-2. 
Here laser oscillation on the P(10) transition of the 9-8 band, for example, increases the population of 
the J = 10 level of v = 8, causing a corresponding enhancement of the power output of the ^(11) 
transition of the 8-7 band. 

The gain coefficient of a molecular gas laser varies from one rotational transition to the next 
within each vibrational band. Because rotational thermalization times are typically very much shorter 
than vibrational level lifetimes, the population density of the rotational levels within each vibrational 
state can be described by a Boltzman distribution. Figure 8-3 gives the normalized gain as a function 
of upper level J for the case of transitions that are inhomogeneously (Doppler) broadened. The upper 
and lower level populations N v and N v . are described by a Boltzman distribution at the same tem- 
perature T. Note that gain is possible on some P-branch transitions, even when there is no complete 
inversion of vibrational population (NJN V > < 1). Gain for such "partial inversions" is not possible 
for i?-branch transitions. For both types of transitions, as T is lowered the gain increases and the J 
value of the highest gain transition is lowered. Use has been made of this gain enhancement at low 
temperatures in practical, continuous CO lasers. 



8 Molecular Gas Lasers 



301 



= 12 






^ 


X 


u 





H"EHE?= 



mm 



(12)-. 



= 10 



V = 5 
■J = 









J 


















\ 






, t 


«■ — 


— 


^ 








\ 


i 


V. 


{ 








fe. 








L 




V 










(d) 








\ 


1 


















\ 













TIME-*20/xSEC/DIV 

Fig. 8-2. Typical cascade laser power outputs for the 
vibrational-rotational transitions of COCA'S + electronic ground 
state), (a) P 9 . 8 (9) at 5.26310/1; (b) P 8 . 7 (10) at 5.20345/xm; (c) P 7 .6(H) 
at 5.14530/im; and (d) P 6 . 5 (12) at5.08845/im. (Energy level diagram 
at the left showing pertinent vibrational-rotational levels is not to 
scale.) (Ref. 74) 



„ . 


6 


<fr 




o 




X 


4 


o 










? 


*£ 




< 




O 





Q 




UJ 




M 


-2 


_J 




< 




5 


-4 


tr 




o 




7* 






-6 



T=300°K N v /N v / 



0.8 
0.9 
1.0 




P-BRANCH 
R- BRANCH 



32 36 40 



20 24 28 

J 

Fig. 8-3. Normalized <x P (J - 1) and <x. R (J - 1) (for 7-6 vibrational-rotational 
band of CO) plotted as a function of upper level J for T= 300 °K and NJN V - = 
0.8, 0.9, 1.0, 1.1, and 1.2. (Ref. 74) 



302 Handbook of Lasers 

POLYATOMIC MOLECULAR GAS LASERS 

Notation for Polyatomic Molecular Gas Lasers 

VIBRATIONAL STATE ENERGY (in cm" 1 ): 

G = G(v u v 2 ,...,v i ,...,v n ) = Y J ™i(Vi + di/2) + X Z XtM + dJlXvj + dj/2) + 9ij /,. L 

where v u v 2 , . . . , v t , . . . , v n are quantum numbers for the n normal modes of vibration, (o it and 
X H are the vibrational constants of the rth mode, and X tj and g u are vibrational coupling constants 
between modes i and j. For degenerate states, d t is a degeneracy number and l t is a quantum 
number associated with vibrational angular momentum. For nondegenerate states, d t = 1 and 
ffij = h = 0. The vibrational state is denoted (v l v 2 • ■ • v„). For a triatomic molecule v u v 2 , and v 3 
are associated respectively with the symmetric stretching, bending, and asymmetric stretching modes. 
The degenerate bending states of a linear triatomic molecule, for example, are denoted (v,v l 7 2 v,) 
ROTATIONAL LEVEL ENERGY (in cm" 1 ): 
depends on molecular configuration. 
LINEAR MOLECULES: 

F v = F V (J) = B V J(J + 1) - D v J 2 (J + l) 2 + • • • 

as for diatomic molecules. 
SYMMETRIC TOP MOLECULES: 

F v = FJLJ, K) = F V (J) + (A v - B V )K 2 

where A v , B v and D v are rotational constants, and K is a quantum number (0 < K < J) corre- 
sponding to a component of J. There are (2 J + 1) rotational sublevels for each value of J, but 
the K and — K sublevels are degenerate. 
SPHERICAL TOP MOLECULES: 
Same as for linear molecules. 
ASYMMETRIC TOP MOLECULES: 

F v = F V (J, K a - K c ) 

As for symmetric top molecules, there are (2J + 1) rotational sublevels for each value of /, but 
these are now all different. Energy levels are denoted by J KaKc , where < (K a , K c ) < J and K a + K c 
= J or J + 1. Quantitative formulae for F v are quite elaborate except for small values of J 
TOTAL ENERGY: 

E = G + F V 

All known laser transitions for polyatomic molecules are in the ground electronic state 
TRANSITION FREQUENCY: 

v(incm- 1 ) = E uppeT -E lower 

The definitions for diatomic molecules hold here as well. For symmetric top molecules, the values 
of J and K are included in the notation. For asymmetric top molecules, values of J, K a and K c 
are included. The vibrational band is denoted by (v x v 2 • • • y„) upper - ( Vl v 2 • • • y„) W r . 

An Example of a Polyatomic Molecular Gas Laser: C0 2 

Of all the molecular gas lasers, the C0 2 laser is probably the most important both commercially 
and scientifically. The large gain coefficients, high levels of pulsed and continuous power, and high 
efficiencies obtainable in this laser have not been matched by other molecular systems. Moreover, the 
dependence of gain and output power on operating conditions are representative of most of the poly- 
atomic molecular gas lasers. 

An energy level diagram showing the best known 9.4 /mi and 10.4 /mi vibrational-rotational bands 
of C0 2 is given in Figure 8-4. This diagram is typical of those for the linear triatomic molecular lasers, 



8 Molecular Gas Lasers 



303 



3000 



2500 



<-> 2000 



1500 



J 1 / / 














IG | 
1 




4/i m 
BAND 



R(20) 



FERMI 
RESONANCE 



02°0 



Fig. 8-4. A detailed laser transition diagram for the 00°1-10°0 and 
00°l-02°0 bands, including rotational levels. (Ref. 12) 

including CS 2 and N 2 0, and is similar to those for HCN and OCS. More complicated energy level 
schemes are encountered for the asymmetric top molecules (H 2 0, H 2 S and S0 2 ), as described above. 

In the case of C0 2 , alternate rotational levels in each vibrational state are missing because of 
symmetry properties. The thermal distribution of rotational level population in the 00° 1 vibrational 
state for two temperatures is given in Figure 8-5. The measured gain distribution in a typical C0 2 
amplifier is given in Figure 8-6 for the 10.4 fim, 00°1-10°0 band. The gain coefficient for the P-branch 
is higher than that for the P-branch, as described above for the diatomic molecular lasers. The roles 
of the N 2 and He additives and detailed discussions of the various excitation mechanisms involved in 
C0 2 lasers are treated extensively in the references listed in Section 8.3.1. 

Figures 8-7 through 8-10 show the variation of gain in % per meter with discharge current, wall 

30 r 



N 



20 



10 







Nj a(2J + l)e 



kT 



-T=400°K 



I000°K 



lllii 



1_L 



9 19 29 39 49 59 

ROTATION QUANTUM NUMBER J 

Fig. 8-5. Thermal distribution of rotational level population in the 00° 1 
upper laser state. (Ref. 12) 



304 Handbook of Lasers 



1.2 



|_< I < I I I I I I 
<oQ°„ 

8 



00° I- I0°0 
8 C0 2 -N 2 -He 




0.4 



0.2-o 



l 1 l I ■ I r 



8 



16 24 32 40 48 
LOWER LEVEL J VALUE 



Fig. 8-6. Gain distribution for individual vibra- 
tional-rotational transition in the P and R branches 
of the 00°1-10°0 band. Amplifier tube bore is 2.54 
cm; gas mixture and flow velocity are: C0 2 (0.65 torr), 
N 2 (1.4 torr) and He (2.9 torr); v = 192 cm/sec. (Ref. 
12) 



500 



400 



300 



200 



100 



-•- 12 MM BORE 
-+-37 MM BORE 



C0 2 ; N 2 <He 
(2: 1.6 4.5 TORR) 



- C0 2 Ng 
(I.I.5T0RR) 




C0 2 ■■ N 2 He 
(0.8 I 2 TORR) 

C0 2 :He 
(2^4 TORR) 



DISCHARGE CURRENT (MA) 

Fig. 8-7. Gain versus discharge current for var- 
ious flowing C0 2 gas media at optimum mixture ratios 
and a constant C0 2 flow rate of 150 cm 3 /min in 12 and 
37 mm bore amplifier tubes. (Ref. 12) 



40 


^"^ x *^ 




_ 30 
cc 

UJ 

1- 

UJ 


X ^" 


>oi 


^ 20 


C0 2 : He 
2 : 6 TORR 




z 

S io 


2 2 mm BORE 
~ Iqpj ■ 15 m A 

1 1 I 


' 



20 40 60 80 100 

AMPLIFIER WALL TEMPERATURE (°C) 

Fig. 8-8. Effect of wall temperature on optimum gain 
of a CQ 2 -He laser amplifier. (Ref. 12) 



8 Molecular Gas Lasers 



305 



temperature, gas flow rate and C0 2 pressure, for C0 2 laser amplifiers. In Figure 8-7, the C0 2 flow rate 
is maintained constant at 150 cm 3 /min, and the discharge current is varied for several mixtures in 
tubes of either 12 mm or 37 mm bore. The effect of variation of wall temperature, which in turn affects 
gas temperature, on the gain of C0 2 -He amplifier operating at optimum current is given in Figure 8-8. 
The dependence of the gain of several mixtures in 12 and 22 mm bore tubes on the flow rate of C0 2 
is given in Figure 8-9. Gas mixtures and pressures are near optimum in each case. Figure 8-10 gives 
the dependence of gain on C0 2 pressure for several gas mixtures. The amplifier tube bore is 22 mm 
and the C0 2 flow rate is 100 cm 3 /min. 



600 



500 - 



_400 



100 




22MM BORE 



.XX*" 



(1.3 = 1.0=4) 



100 



200 



300 



400 



500 



C0 2 FLOW RATE (CM 3 /MIN AT STP) 



Fig. 8-9. Effect of gas flow on gain of 
C0 2 -N 2 -He and C0 2 -CO-He laser amplifiers in 12 
and 22 mm bore tubes. Gas pressure and mixture ratio 
are near optimum in each case. (Ref. 12) 



100 



80 



LU 

u 60 



< 40 



20 



22MM BORE 

R =I00CM 3 /MIN STP 
C0 2 




vco 2 : CO 

(x: I T0RR) 



2.5 



0.5 10 15 2.0 

C0 2 PRESSURE, x (TORR) 

Fig. 8-10. Gain versus C0 2 pressure for various gas mix- 
tures in a 22 mm bore amplifier tube. C0 2 flow rate is 100 
cm 3 /min. (Ref. 12) 



306 Handbook of Lasers 

TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS 



Wavelength, Frequency," _, .,. Relative 

\ r..~.\ i -i\ Transition , h 

Avac(/^w) v(cm x ) strength" 



8.2.1 CN LASER 

TRANSITIONS IN THE JT 2 S (4-3) BAND 



5.1838 
5.1946 
5.2055 



1929.08 
1925.09 
1921.05 



P(9) 


0.54 


P(10) 


0.42 


P(H) 


0.04 



Wavelength Frequency? 



Ayac (\i-ni) 



v(cm *) 



Transition 



Relative 
strength 



8.2.2a CO LASER 
TRANSITIONS BETWEEN THE fi'S - A l W ELECTRONIC STATES e 







0-3 band 




0.55921 


17882.2 


QUI) 


0.3 


0.55949 


17873.3 


Q(10) 


0.5 


0.55975 


17864.9 


Q(9) 


1. 


0.55998 


17857.6 


Q( 8)orR(13) 


1. 


0.56019 


17850.9 


Q(7) 


1. 


0.56040 


17844.3 


Q(6) 


0.3 


0.56053 


17840.1 


Q(5) 
0-4 band 


0.02 


0.60646 


16489.2 


Q(9) 


0.5 


0.60674 


16481.6 


Q(8) 


0.8 


0.60699 


16474.8 


Q(7) 


1. 


0.60722 


16448.6 


Q(6) 


0.6 


0.60742 


16463.1 


Q(5) 


0.3 


0.60759 


16458.6 


Q(4) 
0-5 band 


0.03 


0.65973 


15157.7 


Q(10) 


0.06 


0.66013 


15148.5 


Q(9) 


0.3 


0.66049 


15140.2 


QX 8)orP(13) 


0.7 


0.66082 


15132.7 


Q(7) 


1. 


0.66109 


15126.5 


Q(6) 


0.4 


0.66133 


15121.0 


Q(5) 


0.2 


0.66153 


15116.4 


0(4) 


0.02 



a ±0.05 cm" 1 . 

b Total peak power > 10 mW (all lines). 

c See Ref. 77. Observed during flash photolysis of cyanogen (C 2 N 2 ) in a quartz laser tube. Pressure 15-20 Torr C 2 N 2 . 
Pump pulse minimum 500 Joules. 
d ±10- 5 M m. 
e See Ref. 53. Observed in a pulsed (25 pps) discharge (80 amperes peak) in a 1.17 m long, 10 mm i.d. tube. 



8 Molecular Gas Lasers 307 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency TransMon Remarks 

Avac (fJ-m) v ( Cm ) 



8.2.2b CO LASER 

TRANSITIONS IN THE X^ + ELECTRONIC GROUND STATE"" 







5-4 band 




5.08691 


1965.83 


P(18) 


c 


5.09806 


1961.53 


P(19) 


c 


5.10937 


1957.19 


P(20) 


c 


5.12079 


1952.82 


P(21) 


c 


5.13237 


1948.42 


P(22) 


c 


5.14405 


1943.99 


P(23) 


c 


5.15597 


1939.50 


P(24) 


c 


5.16794 


1935.01 


P(25) 


c 


5.18009 


1930.47 


P(26) 


c 


5.19236 


1925.91 


P(27) 
6-5 band 


c 


5.03755 


1985.09 


P(7) 


a 


5.04750 


1981.18 


P( 8) 


a,d 


5.05755 


1977.24 


P( 9) 


ad 


5.06773 


1973.27 


P(10) 


a.d 


5.07807 


1969.25 


P(ll) 


a,d 


5.08845 


1965.23 


P(12) 


a,d 


5.09905 


1961.15 


P(13) 


a,d,e 


5.10985 


1957.00 


P(14) 


a,f 


5.12030 


1953.01 


P(15) 


g 


5.13157 


1948.72 


P(16) 


c,g 


5.14268 


1944.51 


P(17) 


c,g 


5.15390 


1940.28 


P(18) 


c 


5.16527 


1936.00 


P(19) 


c 


5.17681 


1931.69 


P(20) 


c 


5.18848 


1927.35 


P(21) 


c 


5.20026 


1922.98 


P(22) 


c 


5.21218 


1918.58 


P(23) 


c 


5.22422 


1914.16 


P(24) 


c 


5.23649 


1909.68 


P(25) 


c 


5.24882 


1905.19 


P(26) 


c 


5.26137 


1900.66 


P(27) 


c 


5.27396 


1896.11 


P(28) 
7-6 band 


c 


5.10410 


1959.21 


P(7) 


a 


5.11418 


1955.35 


P(8) 


a,d 


5.12445 


1951.43 


P(9) 


a,d 


5.13485 


1947.48 


P(10) 


a,d 


5.14530 


1943.52 


P(ll) 


a,g 



a See Ref. 70 and 72. Observed in a pulsed discharge in CO. 

b See Ref. 28. A total of 300 transitions from the 1-0 band through 16-15 band, including many identified as R branch transi- 
tions observed during flash photolysis of CS 2 -0 2 mixtures. Frequency selective resonator required. No wavelengths given. 
' c See Ref. 72. Observed in a cw discharge. Laser tube jacket temperature 195°K for transitions with low J, 290 K for 



transitions with high J. 

d See Ref. 2. Observed in a pulsed discharge in CS 2 -0 2 mixtures 



e See Ref. 75. Observed during flash photolysis of CS 2 -0 2 mixtures. 

f See Ref. 69. Observed in a cw discharge in flowing mixtures of CO, 2 , and He. Laser tube jacket cooled to liquid N 2 
temperature. Other transitions observed; wavelengths not tabulated. Rotating mirror Q-switching gives 7.7 kW total peak power. 
8 See Ref. 58. Observed in a pulsed discharge in CO/C0 2 mixtures. 



308 



Handbook of Lasers 



TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency 
Avac (pm) v(cw _1 ) 



Transition 



Remarks 



8.2.2b CO LASER (Continued) 



5.15595 


1939.51 


P(12) 


a,b,c,d,e 


5.16666 


1935.49 


P(13) 


a,b,d,e 


5.17765 


1931.38 


P(14) 


a,b,d,e 


5.18865 


1927.28 


P(15) 


a,b d 


5.19980 


1923.15 


P(16) 


a 


5.21110 


1918.98 


P(17) 


b,f 


5.22256 


1914.77 


P(18) 


b,f 


5.23420 


1910.51 


P(19) 


b.f 


5.24590 


1906.25 


P(20) 


b,f 


5.25776 


1901.95 


P(21) 


f 


5.26981 


1897.60 


P(22) 


f 


5.28189 


1893.26 


P(23) 


f 


5.29423 


1888.85 


P(24) 


f 


5.30674 


1884.40 


P(25) 


f 


5.31924 


1879.97 


P(26) 


f 


5.33204 


1875.45 


P(27) 


f 


5.34494 


1870.93 


P(28) 
8-7 band 


f 


5.17220 


1933.41 


P( 7) 


a 


5.18250 


1929.57 


P( 8) 


a 


5.19290 


1925.71 


P( 9) 


a 


5.20345 


1921.80 


P(10) 


a 


5.21410 


1917.88 


POD 


a,d 


5.22498 


1913.88 


P(12) 


a,c,d,e 


5.23600 


1909.85 


P(13) 


a,d,e 


5.24710 


1905.81 


P(14) 


a,b,d,f 


5.25835 


1901.74 


P(15) 


b.f 


5.26966 


1897.66 


P(16) 


b,f 


5.28118 


1893.52 


P(17) 


b,f 


5.29284 


1889.34 


P(18) 


b,f 


5.30467 


1885.13 


P(19) 


b,f 


5.31663 


1880.90 


P(20) 


b,f 


5.32871 


1876.63 


P(21) 


b,f 


5.34095 


1872.33 


P(22) 


f 


5.35334 


1867.99 


P(23) 


f 


5.36585 


1863.64 


P(24) 


f 


5.37860 


1859.22 


P(25) 


f 


5.39141 


1854.80 


P(26) 


f 


5.40442 


1850.34 


P(27) 


f 


5.41751 


1854.87 


P(28) 
9-8 band 


f 


5.24195 


1907.69 


P(7) 


a 


5.25250 


1903.85 


P( 8) 


a 


5.26310 


1900.02 


P( 9) 


a,d 


5.27380 


1896.17 


P(10) 


a,c,d 


5.28465 


1892.27 


P(H) 


a,c,d,e 



a See Ref. 70 and 72. Observed in a pulsed discharge in CO. 

b Sec Ref. 58. Observed in a pulsed discharge in CO/C0 2 mixtures. 

c See Ref. 75. Observed during flash photolysis of CS 2 -0 2 mixtures. 

d See Ref. 2. Observed in a pulsed discharge in CS 2 -0 2 mixtures. 

e See Ref. 69. Observed in a cw discharge in flowing mixtures of CO, 2 , and He. Laser tube jacket cooled to liquid N 2 
temperature. Other transitions observed; wavelengths not tabulated. Rotating mirror Q-switching gives 7.7 kW total peak power. 

f See Ref. 72. Observed in a cw discharge. Laser tube jacket temperature 195°K for transitions with low J, 290°K for 
transitions with high J. 



8 Molecular Gas Lasers 309 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, 



Frequency 
v(cm~ l ) 



Transition 



Remarks 



8.2.2b CO LASER (Continued) 



5.29570 
5.30695 
5.31820 
5.32964 
5.34127 

5.35298 
5.36485 
5.37692 
5.38906 
5.40138 

5.41385 
5.42648 
5.43926 
5.45225 
5.46533 

5.47852 
5.49191 



5.32415 
5.33490 
5.34590 
5.35695 
5.36820 

5.37950 
5.39110 
5.40274 
5.41457 
5.42651 

5.45087 
5.46328 
5.47582 
5.48850 
5.50138 

5.51442 
5.52762 
5.54091 
5.55438 



5.4080 
5.4196 
5.4299 
5.4425 
5.45402 

5.46571 
5.47763 
5.48968 
5.50189 
5.51421 



1888.32 
1884.32 
1880.33 
1876.30 
1872.21 

1868.12 
1863.98 
1859.80 
1855.61 
1851.38 

1847.11 
1842.82 
1838.49 
1834.11 
1829.72 

1825.31 
1820.86 



1878.23 
1874.45 
1870.59 
1866.73 
1862.82 

1858.91 
1854.91 
1850.91 
1846.87 
1842.80 

1834.57 
1830.40 
1826.21 
1821.99 
1817.73 

1813.43 
1809.10 
1804.76 
1800.38 



1849.11 
1845.15 
1841.65 
1837.40 
1833.51 

1829.59 
1825.61 
1821.60 
1817.56 
1813.50 



P(12) 
P(13) 
P(14) 
P(15) 
P(16) 

P(17) 
P(18) 
P(19) 
P(20) 
P(21) 

P(22) 
P(23) 
P(24) 
P(25) 
P(26) 

P(27) 
P"(28) 

10-9 band 
P( 8) 
P(9) 
P(10) 
P(H) 
P(12) 

P(13) 
P(14) 
P(15) 
P(16) 
P(17) 

P(19) 
P(20) 
P(21) 
P(22) 
P(23) 

P(24) 
P(25) 
P(26) 
P(27) 

11-10 band 
P(9) 
P(10) 
P(1D 
P(12) 
P(13) 

P(14) 
P(15) 
P(16) 
P(17) 
P(18) 



a,b,c,d 

a,b,c,e 

a,b,c,d,e 

b,f,e 

b,f,e 

b,f 
b,f 
b,f 
b,f 
b,f 

b,f 

f 

f 

f 

f 

f 
f 



a 

a 

a,c 

a,c 

a,b,c,d,e 

a,b,c,d 

b,e,f 

b,e,f 

b,f 

b,c,f 

b,f 
b,f 
b,f 
b,f 
f 

f 
f 
f 
f 



c 

c 

c,d 

c 

b,e,f 

b,e,f 

b,e,f 

b,e,f 

b,f 

b,f 



a See Ref. 70 and 72. Observed in a pulsed discharge in CO. 

b See Ref. 58. Observed in a pulsed discharge in CO/CO z mixtures. 

c See Ref. 75. Observed during flash photolysis of CS 2 -0 2 mixtures. 

d See Ref 69. Observed in a cw discharge in flowing mixtures of CO, 2 , and He. Laser tube jacket cooled to liquid N 2 
temperature. Other transitions observed; wavelengths not tabulated. Rotating mirror Q-switchmg gives 7.7 kW total peak power. 

e See Ref. 2. Observed in a pulsed discharge in CS 2 -0 2 mixtures. tnKO „ * 4 ... tU i , -, on ou fA , 

f See Ref. 72. Observed in a cw discharge. Laser tube jacket temperature 195°K for transitions with low J, 290 K for 
transitions with high J. 



310 



Handbook of Lasers 



TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency „ 

Avac(^w) Kern" 1 ) Transition Remarks 



8.2.2b CO LASER (Continued) 



5.52667 


1809.41 


P(19) 


a,b 


5.53927 


1805.29 


P(20) 


a,b 


5.55207 


1801.13 


P(21) 


b 


5.56503 


1796.94 


P(22) 


b 


5.59147 


1788.44 


P(24) 


b 


5.60494 


1784.14 


P(25) 
12-11 band 


b 


5.4842 


1823.41 


P( 9) 


c 


5.4946 


1819.96 


P(10) 


c,d 


5.5072 


1815.81 


P(1D 


c,d 


5.5187 


1812.02 


P(12) 


c,e 


5.5299 


1808.35 


P(13) 


c,e 


5.5424 


1804.28 


P(14) 


c,e 


5.57904 


1792.42 


P(17) 


b 


5.59158 


1788.40 


P(18) 


a,b 


5.60436 


1784.33 


P(19) 


a,b 


5.61725 


1780.23 


P(20) 


b 


5.64350 


1771.95 


P(22) 


b 


5.65687 


1767.76 


P(23) 


b 


5.67044 


1763.53 


P(24) 


b 


5.68414 


1759.28 


P(25) 
13-12 band 


b 


5.5971 


1786.64 


P(12) 


c,d 


5.6087 


1782.95 


P(13) 


c,e 


5.63304 


1775.24 


P(15) 


b 


5.65816 


1767.36 


P(17) 


b 


5.67098 


1763.36 


P(18) 


b 


5.68396 


1759.34 


P(19) 


b 


5.69712 


1755.27 


P(20) 


b 


5.71042 


1751.18 


P(21) 


b 


5.73754 


1742.91 


P(23) 


b 


5.75142 


1738.70 


P(24) 
14-13 band 


b 


5.6546 


1769.18 


P(10) 


c 


5.6654 


1765.10 


P(ll) 


c,d 


5.6780 


1761.18 


P(12) 


c 


5.71361 


1750.21 


P(15) 


b 


5.72642 


1746.29 


P(16) 


b 


5.73931 


1742.37 


P(17) 


b 


5.75243 


1738.40 


P(18) 


b 


5.77911 


1730.37 


P(20) 


b 


5.79264 


1726.33 


P(21) 


b 


5.80636 


1722.25 


P(22) 


b 


5.82031 


1718.12 


P(23) 


b 


5.83441 


1713.97 


P(24) 


b 


5.84874 


1709.77 


P(25) 


b 



a See Ref. 58. Observed in a pulsed discharge in CO/C0 2 mixtures. 

b See Ref. 72. Observed in a cw discharge. Laser tube jacket temperature 195°K for transitions with low J, 290°K for 
transitions with high J. 

c See Ref. 75. Observed during flash photolysis of CS 2 -0 2 mixtures. 

d See Ref. 69. Observed in a cw discharge in flowing mixtures of CO, 2 , and He. Laser tube jacket cooled to liquid N 2 
temperature. Other transitions observed; wavelengths not tabulated. Rotating mirror Q-switching gives 7.7 kW total peak power. 

c See Ref. 2. Observed in a pulsed discharge in CS 2 -0 2 mixtures. 



8 Molecular Gas Lasers 311 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency Transition Remarks 

Avac (pm) v(cm ') 



8.2.2b CO LASER {Continued) 







15-14 band 




5.78346 


1729.07 


P(H) 


a 


5.79633 


1725.23 


P(15) 


a 


5.80927 


1721.39 


P(16) 


a 


5.83581 


1713.56 


P(18) 


a 


5.84935 


1709.59 


P(19) 


a 


5.86300 


1705.61 


P(20) 


a 


5.87689 


1701.58 


P(21) 


a 


5.89088 


1697.54 


P(22) 


a 


5.90507 


1693.46 


P(23) 


a 


5.91951 


1689.33 


P(24) 
16-15 band 


a 


5.89450 


1696.50 


P(16) 


a 


5.90789 


1692.65 


P(17) 


a 


5.92156 


1688.74 


P(18) 


a 


5.94923 


1680.89 


P(20) 


a 


5.96338 


1676.90 


P(21) 


a 


5.97768 


1672.89 


P(22) 
17-16 band 


a 


5.98177 


1671.75 


P(16) 


a 


5.99553 


1667.91 


P(17) 


a 


6.00939 


1664.06 


P(18) 


a 


6.02348 


1660.17 


P(19) 


a 


6.03774 


1656.25 


P(20) 
18-17 band 


a 


6.05755 


1650.83 


P(15) 


a 


6.07145 


1647.05 


P(16) 


a 


6.0856 


1643.22 


P(17) 


a 


6.09961 


1639.45 


P(18) 


a 


6.12845 


1631.73 


P(20) 
19-18 band 


a 


6.14904 


1626.27 


P(15) 


a 


6.16288 


1622.62 


P(16) 


a 


6.17712 


1618.88 


P(17) 


a 


6.1924 


1614.88 


P(18) 


a 


6.2068 


1611.14 


P(19) 
20-19 band 


a 


6.24320 


1601.74 


P(15) 


a 


6.25712 


1598.18 


P(16) 


a 


6.27228 


1594.32 


P(17) 


a 


6.2870 


1590.58 


P(18) 
21-20 band 


a 


6.3260 


1580.78 


P(14) 


a 


6.33936 


1577.45 


P(15) 


a 


6.3552 


1573.51 


P(16) 


a 


6.38476 


1566.23 


P(17) 
22-21 band 


a 


6.4252 


1556.37 


P(14) 


a 


6.43968 


1552.87 


P(15) 


a 


6.45488 


1549.22 


P(16) 


a 


6.4704 


1545.50 


P(17) 


a 



a See Ref. 72. Observed in a cw discharge. Laser tube jacket temperature 195°K for transitions with low J, 290°K for 
transitions with high J. 



312 Handbook of Lasers 

TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency „ 

Avac(^/n) v(cm- 1 ) Transition Remarks 



8.2.2b CO LASER (Continued) 



6.5120 
6.5268 
6.5424 
6.5584 



6.6476 
6.6632 





23-22 band 




1535.63 


P(13) 


a 


1532.14 


P(14) 


a 


1528.49 


P(15) 


a 


1524.76 


P(16) 
24-23 band 


a 


1504.30 


P(15) 


a 


1500.78 


P(16) 


a 



Wavelength, Frequency Transition 

Avac (H vicm' 1 ) HBr 79 HBr 8 



8.2.3a HBr LASER 
TRANSITIONS 11 







1-0 band 


4.0170 


2489.40 


P(4) 




4.0176 


2489.05 




P(4) 


4.0470 


2470.97 


P(5) 




4.0475 


2470.63 




P(5) 


4.0783 


2452.03 


P(6) 




4.0788 


2451.68 




P(6) 


4.1107 


2432.70 


P(7) 




4.1112 


2432.36 




P(7) 


4.1442 


2412.99 


P(8) 




4.1448 


2412.68 




P(8) 


4.1796 


2392.56 




P(9) 






2-1 band 


4.1653 


2400.78 


P(4) 




4.1658 


2400.47 




P(4) 


4.1970 


2382.68 


P(5) 




4.1975 


2382.35 




P(5) 


4.2295 


2364.36 


P(6) 




4.2633 


2345.58 


P(7) 




4.2639 


2345.26 




P(7) 


4.2988 


2326.23 


P(8) 




4.2994 


2325.92 




P(8) 


4.3354 


2306.60 


P(9) 




4.3359 


2306.30 




P(9) 






3-2 band 


4.3250 


2312.15 


P(4) 




4.3255 


2311.85 




P(4) 


4.3579 


2294.68 


P(5) 




4.3585 


2294.39 




P(5) 


4.3925 


2276.61 


P(6) 




4.3931 


2276.32 




P(6) 


4.4281 


2258.29 


P(7) 




4.4307 


2558.00 




P(7) 


4.4652 


2239.52 


P(8) 




4.4658 


2239.26 




P(8) 



a See Ref. 72. Observed in a cw discharge. Laser tube jacket temperature 195°K for transitions with low J. 290°K for 
transitions with high J. 

b See Ref. 18. Observed in a pulsed discharge in a 2 m long, 32 mm i.d. tube in H 2 and Br 2 mixtures; pressure (total) 1.5- 
3.5 Torr. 



8 Molecular Gas Lasers 313 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, 

Avac V>W) 


Frequency 
v(cm~ l ) 


Transition 
HBr 79 HBr 81 


8.2.3a HBr LASER (Continued) 




4.5041 
4.5047 


2220.20 
2219.92 


P(9) 


P(9) 






4-3 band 


4.5330 
4.5335 
4.5691 
4.5696 
4.6070 


2206.07 
2205.81 
2188.61 
2188.35 
2170.61 


P(5) 
P(6) 
P(7) 


P(5) 
P(6) 


4.6076 
4.6463 
4.6467 


2170.35 
2152.27 
2152.04 


P(8) 


P(7) 
P(8) 



8.2.3b HBr LASER 
PURE ROTATIONAL TRANSITIONS" 







v = 


19.399 


515.49 


R(33) 


20.360 


491.16 


R(31) or R(31) 


20.896 


478.56 


R(30) 


20.949 


477.35 


R(30) 


21.501 


465.09 


R(29) or R(29) 


22.136 


451.75 


R(28) 


30.948 


323.12 


R(19) or R(19) 


32.469 


307.99 


R(18) or R(18) 


19.988 


500.30 


v = l 
R(33) or R(33) 


21.546 


464.12 


R(30) 


30.445 


328.46 


R(20) or R(20) 


31.849 


313.98 


R(19) or R(19) 


33.409 


299.32 


R(18) or R(18) 


22.226 


449.92 


v = 2 
R(30) 


22.855 


437.54 


R(29) or R(29) 


31.368 


318.80 


R(20) or R(20) 


32.799 


304.89 


R(19) 


40.526 


246.76 


R(15)or R(15) 

v = 3 


29.786 


335.73 


R(22) 


23.436 


426.69 





Wavelength, Frequency Transition 

AvacOim) v(cm- 1 ) DBr 79 DBr 8 



8.2.3c DBr LASER* 







2-1 band 


5.8049 


1722.67 


P(8) 
3-2 band 


5.8620 


1705.91 


P(5) 


5.8626 


1705.43 


P(5) 


5.8928 


1696.98 


P(6) 


5.8944 


1696.52 


P(6) 


5.9246 


1687.89 


P(7) 



a See Ref 3. Observed in a pulsed discharge in a 3.2 m long, 102 mm i.d. tube in BBr 3 (0.05-0.2 Torr) and H 2 0. 

b See Ref! 18. Observed in a pulsed discharge in a 2 m long, 32 mm i.d. tube; pressure 0.6 Torr D 2 and 0.3 Torr Br 2 



314 Handbook of Lasers 

TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency 


Transition 




AvacCjU/tt) v(cm~ l ) 




DBr 79 


DBr 81 






8.2.3c DBr LASER {Continued) 






5.9261 


1687.45 






P(7) 




5.9573 


1678.60 




P(8) 






5.9590 


1678.13 






P(8) 










4-3 band 




6.0209 


1660.88 




P(5) 






6.0225 


1660.45 






P(5) 




6.0529 


1652.10 




P(6) 






6.0544 


1651.69 






P(6) 




6.0858 


1643.18 




P(7) 






6.0873 


1642.76 






P(7) 




6.1200 


1634.00 




P(8) 






6.1216 


1633.57 






P(8) 




6.1546 


1624.80 




P(9) 






6.1562 


1624.39 






P(9) 




6.1903 


1615.42 




P(10) 






6.1918 


1615.03 






P(10) 




6.2272 


1605.85 




P(ll) 






6.2289 


1605.43 






P(H) 










5-4 band 




6.2237 


1606.75 






P(6) 




6.2566 


1598.32 




P(7) 






6.2581 


1597.93 






P(7) 




6.2916 


1589.41 




P(8) 






6.2932 


1589.01 






P(8) 




6.3279 


1580.31 




P(9) 






6.3294 


1579.92 






P(9) 




Wavelength, 


Frequency 


Transition 




™~ 


Avac (pm) 


vicm' 1 ) 


HCI 35 


HCI 37 


Remarks 






8.2.4a HCI LASER 










2-1 band 






3.7071 


2697.52 


P(4) 




a,b,c 




3.7383 


2675.01 


P(5) 




a,b,c,d 




3.7408 


2673.23 




P(5) 


b 




3.7710 


2651.82 


P(6) 




a,b,c,d 




3.7735 


2650.08 




P(6) 


b 




3.8050 


2628.13 


P(7) 




a,b,c,d 




3.8074 


2626.45 




P(7) 


b 




3.8401 


2604.09 


P(8) 




a,b,c,d 




3.8425 


2602.48 




P(8) 


b 




3.8768 


2579.42 


P(9) 




b,c,d 




3.9149 


2554.34 


P(10) 




b,c,d 





a See Refs. 44 and 9 and references cited therein. Observed during a flash initiated reaction of H, and CI, in a 0.60 m long 
tube; pressure 2-10 Torr total. Flash energy 1300 Joules. * 2 s 

(0 1 Torrt 6 RCf " 18 ' ° bserved in a pulsed dischar ge in a 2 m long, 32 mm i.d. tube in a flowing mixture of H 2 (1 Torr) and Cl 2 

« » c ^ Se f Re £" T i^w« Served in a pulsed dischar g e in a 2 m long, 25 mm i.d. tube in mixtures of H 2 (1-3 Torr) and CI, (0.07- 
0.25 Torr) or NOC1 (0.2 Torr). Also observed: P(4)-P(ll), 1-0 band; P(ll)-P(13), 2-1 band; P(10), 3-2 band; and P(5)-P(9), 4-3 
band; wavelengths not given. 

„ J, S , e . e „ Ref- 64, observed in a Pulsed discharge in a 0.50 m long, 20 mm i.d. tube in flowing mixtures of HI (0.2-0.4 Torr) 
and Cl 2 (1.2 Torr). Also observed were P(l 1)-P(13), 2-1 band and P(10)-P(12), 3-2 band. 



8 Molecular Gas Lasers 315 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, 
Avac (fJ-m) 



Frequency 
v(cm~ l ) 



Transition 
HCl 35 HCI 3 



Remarks 



8.2.4a HCl LASER (Continued) 







3-2 band 




3.8509 


2596.79 


P(4) 




a,b 


3.8840 


2574.70 


P(5) 




a,b,c 


3.9181 


2552.26 


P(6) 




a,b,c 


3.9205 


2550.70 




P(6) 


a 


3.9536 


2529.31 


P(7) 




a,b,c 


3.9560 


2527.79 




P(7) 


a 


3.9909 


2505.68 


P(8) 




a,b,c 


4.0295 


2481.69 


P(9) 




a,b,c 



8.2.4b HCl LASER 
PURE ROTATIONAL TRANSITIONS 







v = 







13.8720 


720.921 


R(40) 




d 


14.0994 


709.279 


R(39) 




d 


14.3434 


697.232 


R(38) 




d 


16.2125 


616.809 


R(32) 




d 


16.6085 


602.114 


R(31) 




d 


16.664 


600.10 




R(31) 


e 


17.0340 


587.070 


R(30) 




d,e 


17.4923 


571.686 


R(29) 




d,e 


17.9874 


555.969 


R(28) 




d,e 


17.997 


555.65 




R(28) 


e 


18.522 


539.928 


R(27) 




d 


19.122 


522.96 




R(26) 


e 


20.4106 


489.949 


R(24) 




d 


21.1556 


472.701 


R(23) 




d 


21.9706 


455.175 


R(22) 




d 


22.8637 


437.380 


R(21) 




d 


23.8485 


419.326 


R(20) 




d 


24.9367 


401.023 


R(19) 




d 


26.1462 


382.483 


R(18) 




d 


27.508 


363.53 


R(17) 




e 


16.765 


596.48 


v = 


= 1 
R(32) 


e 


17.125 


583.94 


R(31) 




e 


17.575 


568.99 


R(30) 




e 


18.035 


554.48 


R(29) 




e 


18.555 


538.94 


R(28) 






18.593 


537.84 




R(28) 


e 


19.145 


522.33 




R(27) 


e 


19.7002 


507.628 


R(26) 




d 


20.3455 


491.526 


R(25) 




d 


21.0470 


475.130 


R(24) 




d 



a See Ref. 18. Observed in a pulsed discharge in a 2 m long, 32 mm i.d. tube in a flowing mixture of H 2 (1 Torr) and Cl 2 
(0.1 Torr). 

b See Ref. 35. Observed in a pulsed discharge in a 2 m long, 25 mm i.d. tube in mixtures of H 2 (1-3 Torr) and Cl 2 (0.07- 
0.25 Torr) or NOC1 (0.2 Torr). Also observed: P(4)-P(ll), 1-0 band; P(ll)-P(13), 2-1 band; P(10), 3-2 band; and P(5)-P(9), 4-3 
band; wavelengths not given. 

c See Ref. 64. Observed in a pulsed discharge in a 0.50 m long, 20 mm i.d. tube in flowing mixtures of HI (0.2-0.4 Torr) 
and Cl 2 (1.2 Torr). Also observed were P(ll)-P(13), 2-1 band and P(10)-P(12), 3-2 band. 

d See Ref. 17. Observed in a pulsed (4-40 pps) discharge in a 2 m long, 32 mm i.d. tube in flowing Cl 2 +CH 3 C1, Cl 2 + CH 3 Br 
or Cl 2 + H 2 +CC1F 3 ; pressure (total) 0.5-2 Torr. 

e See Ref. 3. Observed in a pulsed (20 pps) discharge (250-500 amperes) in a 3.2 m long, 102 mm i.d. tube in mixtures of 
BCI3 (0.05-0.18 Torr) and H 2 (0.02-0.05 Torr). 



316 



Handbook of Lasers 



TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, 
A vac (ju-w) 



Frequency 
v{cm ~ ' ) 



Transition 
HC1 35 HCI 3 



Remarks 



8.2.4b HCI LASER (Continued) 



21.8127 


458.449 


R(23) 


a 


22.6514 


441.491 


R(22) 


a 


23.5705 


424.268 


R(21) 


a 


24.6177 


406.215 


R(20) 


a 


24.5833 


406.789 


R(20) 


a 


25.7040 


389.065 


R(19) 
v=2 


a 


19.183 


521.29 


R(28) 


b 


20.9991 


476.215 


R(26) 


a 


24.3178 


411.232 


R(21) 
v=3 


a 


19.783 


505.48 


R(28)? 


b 


19.821 


504.52 




b 



Wavelength, 
Avac (fim) 



Frequency 
v(cm ~ ' ) 



Transition 
DC1 35 DC1 3 



Remarks 



8.2.4c DC1 LASER 







2-1 band 




5.0445 


1982.35 


P(5) 




c 


5.0514 


1979.65 




P(5) 


c 


5.0743 


1970.72 


P(6) 




c 


5.0811 


1968.08 




P(6) 


c 


5.1049 


1958.90 


P(7) 




c,d 


5.1118 


1956.25 




P(7) 


c 


5.1363 


1946.94 


P(8) 




c,d 


5.1431 


1944.35 




P(8) 


c 


5.1688 


1934.67 


P(9) 




c,d 






3-2 band 




5.1511 


1941.35 


P(4) 




c,d 


5.1811 


1930.10 


P(5) 




c,d 


5.1879 


1927.56 




P(5) 


c 


5.2118 


1918.73 


P(6) 




c 


5.2186 


1916.24 




P(6) 


c 


5.2435 


1907.13 


P(7) 




c 


5.2503 


1904.67 




P(7) 


c 


5.2760 


1895.37 


P(8) 




c 


5.2829 


1892.91 




P(8) 


c 


5.3097 


1883.35 


P(9) 




c 


5.3443 


1871.15 


P(10) 




c 


5.3799 


1858.77 


P(ll) 




c 






4-3 band 




5.3244 


1878.13 


P(5) 




c 


5.3562 


1867.01 


P(6) 




c 


5.3629 


1864.65 




P(6) 


c 


5.3889 


1855.66 


P(7) 




c 


5.3956 


1853.36 




P(7) 


c 



a See Ref. 1 7. Observed in a pulsed (4-40 pps) discharge in a 2 m long, 32 mm i.d. tube in flowing Cl 2 + CH 3 C1, Cl 2 + CH 3 Br 
or Cl 2 + H 2 + CC1F 3 ; pressure (total) 0.5-2 Torr. 

b See Ref. 3. Observed in a pulsed (20 pps) discharge (250-500 amperes) in a 3.2 m long, 102 mm i.d. tube in mixtures of 
BC1 3 (0.05-0.18 Torr) and H 2 (0.02-0.05 Torr). 

c See Ref. (18). Observed in a pulsed discharge in a 2m long, 32mm i.d. tube. Pressure 1.5 Torr D 2 and 0.4 Torr Cl 2 . 

d See Ref. 9. Observed during a flash initiated reaction of D 2 and Cl 2 in a 0.6 m long tube; pressure 18 Torr Cl 2 , 175 Torr 
D 2 . Flash energy 2000 Joules. 



8 Molecular Gas Lasers 317 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS {Continued) 



Wavelength, 
Avac (ji-rn) 



Frequency 
v(c/m -1 ) 



Transition 
DC1 35 DC1 3 



Remarks 



5.4295 
5.4577 
5.4935 
5.5304 



8.2.4c DC1 LASER {Continued) 
P(8) 



1841.79 
1832.27 
1820.34 
1808.20 



P(9) 

P(10) 

POD 



5.5084 
5.5423 
5.5776 
5.6137 



1815.38 
1804.31 
1792.89 
1781.36 



5-4 band 
P(6) 
P(7) 
P(8) 
P(9) 



Wavelength, 
Avac (pm) 



Frequency 
v(cm~ x ) 



Transition 



Remarks 



8.2.5a HF LASER 







1-0 band 




2.640 


3788 


P(4) 


b 


2.673 


3741 


P(5) 


b 


2.7075 


3693.50 


P(6) 


b,c 


2.7441 


3644.16 


P(7) 


b,c 


2.7826 


3593.80 


P(8) 


c 


2.8231 


3542.20 


P(9) 


c 


2.8657 


3489.59 


P(10) 


c 


2.9103 


3436.12 


POD 


c 


2.9573 


3381.50 


P(12) 


c 


3.0064 


3326.21 


P(13) 


c 


3.0582 


3269.90 


P(14) 


c 


3.1125 


3212.80 


P05) 
2-1 band 


c 


2.6962 


3708.86 


P(2) 


c 


2.7275 


3666.38 


P(3) 


c 


2.7604 


3622.71 


P(4) 


b,c,d,e 


2.7953 


3577.47 


P(5) 


b,c,d,e 


2.8318 


3531.31 


P(6) 


b,c,d,e 


2.8706 


3483.63 


P(7) 


b,c,d,e 


2.9111 


3435.17 


P(8) 


c,d,e 


2.9539 


3385.34 


P(9) 


c,e 


2.9989 


3334.55 


P(10) 


c,e 


3.0461 


3282.86 


PCM) 


c,e 


3.0958 


3230.18 


P(12) 


c 


3.1480 


3176.60 


P(13) 


c 


3.2029 


3122.14 


P(14) 


c 


3.2603 


3067.22 


P(15) 
3-2 band 


c 


2.8213 


3544.51 


P(2) 


c 


2.8540 


3503.80 


P(3) 


c 



a See Ref. 18. Observed in a pulsed discharge in a 2 m long, 32 mm i.d. tube. Pressure 1.5 Torr D 2 and 0.4 Torr Cl 2 . 

b See Ref. 83. Observed in a cw supersonic stream containing F and H 2 . Atomic fluorine is generated by mixing SF 6 with 
arc-heated N 2 . Continuous laser power 475 watts for 27.6 kW arc heater input. 

c See Ref. 16. Observed in a pulsed (2-10 pps) discharge (50-200 amperes) in a 2 m long, 32 mm i.d. tube; pressure 0.15-1 
Torr total in flowing mixtures of CBrF 3 and H 2 . Other mixtures of CF 4 , CC1F 3 or CC1 2 F 2 and H 2 , CH 4 or CH 3 C1. 

d See Ref. 46. Observed during flash photolysis of UF 6 -H 2 mixtures in a 0.85 m long, 6 mm i.d. tube. 

e See Ref. 8. Observed in a pulsed discharge or during flash photolysis of H 2 , F 2 mixtures. Ten other transitions between 
2960 cm" l and 3416 cm -1 are reported, but identifications are tentative. 



318 



Handbook of Lasers 



TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS {Continued) 



Wavelength, Frequency _ 

A vac (/x W ) v(cm-i) Transition Remarks 



8.2.5a HF LASER {Continued) 



2.8889 
2.9256 
2.9643 

3.0051 
3.0482 



3461.54 
3418.16 
3373.46 

3327.73 
3280.64 



P(4) 
P(5) 
P(6) 

P(7) 
P(8) 



8.2.5b HF LASER 
PURE ROTATIONAL TRANSITIONS 



10.1978 


980.60 


10.4578 


956.23 


10.7439 


930.76 


11.0573 


904.38 


11.4033 


876.94 


11.7854 


848.50 


12.2082 


819.12 


12.6781 


788.76 


13.2009 


757.52 


13.7841 


725.47 


14.4406 


692.49 


16.0215 


624.16 


16.975 


589.10 


18.085 


552.94 


12.2619 


815.53 


12.7006 


787.37 


13.1877 


758.28 


13.7277 


728.45 


15.0163 


665.94 


16.655 


600.42 


17.645 


566.73 


18.8010 


531.89 


20.1337 


496.68 


21.6986 


460.86 


10.5819 


945.01 


10.8117 


924.93 


13.2211 


756.37 


14.2881 


699.88 


16.444 


608.12 


17.327 


577.13 


20.9393 


477.57 


11.5408 


866.49 


17.095 


584.97 


19.1129 


523.21 


20.3513 


491.37 


21.7885 


458.96 



v = 
R(27) 
R(26) 
R(25) 
R(24) 
R(23) 

R(22) 
R(21) 
R(20) 
R(19) 
R(18) 

R(17) 
R(15) 
R(14) 
R(13) 

u=7 
R(22) 
R(21) 
R(20) 
R(19) 
R(17) 

R(16) 
R(15) 
R(13) 
R(12) 
R(H) 

v = 2 
R(29) 
R(28) 
R(21) 
R(19) 
R(16) 

R(15) 
R(12) 

v = 3 
R(27) 
R(16) 
R(14) 
R(13) 
R(12) 



b 

b 

b 

b,c 

b,c 

b,c 
b,c 
b,c 
b,c 
b 

b 
b 
c 
c 



b,c 

b,c 

b 

b 

b 

c 
c 
c 
b 
b 



• See Ref. 16. Observed in a pulsed (2-10 pps) discharge (50-200 amperes) in a 2 m long, 32 mm i.d. tube; pressure 0.15-1 
Torr total in flowing mixtures of CBrF 3 and H 2 . Other mixtures of CF 4 , CC1F 3 or CC1 2 F 2 and H 2 CH 4 or CH,C1 

See Ref. 17. Observed in a pulsed (2-120 pps) discharge (50-200 amperes) in a 2 m long, 32 mm i.d. tube; pressure 0.75-5 
lorr in mixtures of CF 4 and H 2 . Some transitions require mixtures of CC1 3 F, CC1F 3 or CBrF 3 and H 2 

n , ° See n R c er 3 - °£ se ™ d in u a r pulsed (20 PP S > discharge (250-500 amperes) in a 3.2 m long, 102 mm i.d. tube; pressure 0.1- 
U.15 Torr Bb 3 or BF 3 +He. H from impurities. 



8 Molecular Gas Lasers 319 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency 
Avac (/xm) Kcm" 1 ) 



Transition Remarks 



8.2.5c DF LASER 







1-0 band 




3.8298 


2611.10 


P(12) 


a 


3.9572 


2527.06 


P(15) 


a 


4.0032 


2498.02 


P(16) 
2-1 band 


a 


3.6363 


2750.05 


P(3) 


a 


3.6665 


2727.38 


P(4) 


a,b 


3.6983 


2703.98 


P(5) 


a,b 


3.7310 


2680.28 


P(6) 


a,b 


3.7651 


2655.97 


P(7) 


a,b 


3.8007 


2631.09 


P(8) 


a 


3.8375 


2605.87 


P(9) 


a 


3.8757 


2580.16 


P(10) 


a 


3.9155 


2553.97 


P(ll) 


a 


3.9565 


2527.47 


P(12) 


a 


3.9995 


2500.32 


P(13) 


a 


4.1369 


2417.27 


P(16) 


a 


4.1862 


2388.79 


P(17) 
3-2 band 


a 


3.7563 


2662.17 


P(3) 


a 


3.7878 


2640.04 


P(4) 


a 


3.8206 


2617.41 


P(5) 


a,b 


3.8547 


2594.23 


P(6) 


a,b 


3.8903 


2570.51 


P(7) 


a,b 


3.9272 


2546.37 


P(8) 


a 


3.9654 


2521.81 


P(9) 


a 


4.0054 


2496.61 


P(10) 


a 


4.0464 


2471.34 


P(ll) 


a 


4.0895 


2445.29 


P(12) 


a 


4.1798 


2392.46 


P(14) 
4-3 band 


a 


3.9487 


2532.50 


P(5) 


a 


3.9843 


2509.86 


P(6) 


a 


4.0212 


2486.83 


P(7) 


a 



8.2.6a H 2 , HD and D 2 LASERS 

H 2 — TRANSITIONS IN THE (2sct% + - 2/xr I Z H + ) SYSTEM 



0.835190 


11973.32 


(2-l)P(2) 


c,d 


0.887868 


11262.93 


(1-0)P(4) 


c,d 


0.890128 


11234.34 


(1-0)P(2) 


c,d 


1.116520 


8956.40 


(0-0)P(4) 


c,d 


1.122507 


8908.63 


(0-0)P(2) 


c,d 


1.30613 


7656.2 


(0-l)P(4) 


c,d 


1.31658 


7595.4 


(0-l)P(2) 


d 



a See Ref. 16. Observed In a pulsed (2-10 pps) discharge (50-200 amperes) in a 2 m long, 32 mm i.d. tube; pressure 0.15-1 
Torr total in flowing mixtures of CBrF 3 , CF 4 , CC1F 3 or CC1 2 F 2 and D 2 . 

b See Ref. 46. Observed during flash photolysis of UF 6 -D 2 mixtures in a 0.85 m long, 6 mm i.d. tube. 

c See Ref. 4 and 5. Observed in a pulsed (20 pps) discharge in a 1.45 m long, 15 mm i.d. tube; in H 2 or H 2 -D 2 mixtures, 
pressure 3 Torr. 

d See Ref. 6. Observed in a pulsed discharge in a 1.02 m long, 7 mm i.d. tube; pressure 3 Torr H 2 . 



320 Handbook of Lasers 

TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, 



Frequency 
v{cm~ l ) 



Transition 



Remarks 



HD— TRANSITIONS IN THE (2sct% + - 2pa*L*) SYSTEM 

(7-0) Band 
0.9163 10914 a b 

D 2 — TRANSITIONS IN THE Vso'l,? - 2pal£) SYSTEM 



0.827980 
0.953261 



12077.58 
10490.31 



(2-0)P(3) 
(1-0)P(3) 



8.2.6b H 2 , PARA H 2 , HD AND D 2 LASERS 

H 2 — TRANSITIONS IN THE (fl'S* - *% + ) SYSTEM 



0.152325 


65649. 


(2-8) P(3) 


c 


0.156725 


63806.1 


(8-14)P(3) 


c.d? 


0.157199 


63613.8 


(2-9) P(l) 


c,d 


0.157739 


63395.9 


(2-9) P(3) 


c,d? 


0.157919 


63323.8 


(7-13)P(l) 


c 


0.157998 


63291.98 


(7-13)P(2) 


c 


0.158074 


63261.4 


(7-13)P(3) 


d,e 


0.159131 


62841.2 


(3-10)P(l) 


c,d 


0.159340 


62758.9 


(3-10)P(2) 


c 


0.159606 


62654.2 


(3-10)P(3) 


d,e 


0.160448 


62325.3 


(4-ll)P(l) 


d,e 


0.160623 


62257.4 


(4-ll)P(2) 


c 


0.160750 


62208.3 


(6-13)P(l) 


d,e 


0.160839 


62173.8 


(4-ll)P(3) 


d,e 


0.160902 


62149.4 


(6-13)P(3) 


e 


0.161033 


62099.2 


(5-12)P(l) 


e 


0.161165 


62048.1 


(5-12)P(2) 


e 


0.161318 


61989.2 


(5-12)P(3) 


d,e 



PARA H 2 — TRANSITIONS IN THE (B 1 ^* - X 1 ^,) SYSTEM 



0.151994 


65792. 


(2-8) P(2) 


c 


0.156753 


63794.8 


(8-14)P(2) 


c 


0.157434 


63518.8 


(2-9) P(2) 


c 


0.157771 


63383. 


(7-13)R(0) 


c 


0.157998 


63292.0 


(7-13)P(2) 


c 


0.158110 


63247. 


(2-9) P(4) 


c 


0.158140 


63235.3 


(7-13)P(4) 


c 


0.158899 


62933. 


(3-10)R(0) 


c 


0.159340 


62758.9 


(3-10)P(2) 


c 


0.159925 


62529.4 


(3-10)P(4) 


c 


0.160236 


62408. 


(4-ll)R(0) 


c 


0.160594 


62269. 


(6-13)R(0) 


c 


0.160623 


62257.4 


(4-H)P(2) 


c 


0.160829 


62177.7 


(6-13)P(2) 


c 


0.160961 


62126.7 


(6-13)P(4) 


c 



a Unidentified. 

b See Ref. 4 and 5. Observed in a pulsed (20 pps) discharge in a 1.45 m long, 15 mm i.d. tube; in H 2 or H 2 -D 2 mixtures, 
pressure 3 Torr. 

c Additional transitions observed in the same apparatus (40). 

d See Ref. 86. Observed in a pulsed discharge in a 1 m long, 12 mm x 3 mm tube. Maximum power output several hundred 
kW in a 1 ns pulse. 

e See Ref. 39. Observed in a pulsed discharge in a 1.2 m long, 12 mm X 0.4 mm tube. Pressure 20-150 Torr H 2 . Maximum 
power output 1.5 kW in a 2 ns pulse. 



8 Molecular Gas Lasers 321 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency 
Avac (fim) v^cm' 1 ) 



Transition 



Remarks 



PARA H 2 — TRANSITIONS IN THE (B% + - *% + ) SYSTEM (Continued) 



0.161033 
0.161091 
0.161165 
0.161318 
0.161485 



62099.2 
62076.7 
62048.1 
61989.2 
61925.1 



(5-12)P(l) 
(4-ll)P(4) 
(5-12)P(2) 
(5-12)P(3) 
(5-12)P(4) 



HD— TRANSITIONS IN THE (B 1 ^ - X l j£) SYSTEM 



0.157242 
0.159524 
0.159713 
0.160365 
0.160496 

0.160569 
0.160631 
0.160646 
0.160692 
0.160747 

0.160794 
0.160827 
0.160893 
0.161005 
0.161131 



63596 
62686 
62612 
62358 
62307 

62278 
62254 
62248 
62231 
62209 

62191 
62179 
62153 
62110 
62061 



(9-16)P(2),P(3) 

(4-12)P(2) 

(4-12)P(3) 

(5-13)P(l) 

(5-13)P(2) 

(7-15)P(l) 
(7-15)P(2) 
(5-13)P(3) 
(7-15)P(3) 
(7-15)P(4) 

(6-14)P(l) 
(5-13)P(4) 
(6-14)P(2) 
(6-14)P(3) 
(6-14)P(4) 



D 2 — TRANSITIONS IN THE (^E* - X^) SYSTEM 



0.158675 
0.158694 
0.158714 
0.159130 
0.159257 

0.160086 
0.160354 
0.160848 
0.161080 
0.161198 

0.161236 
0.161251 
0.161320 
0.161412 



63021 
63014 
63004 
62841 
62792 

62466 
62360 
62170 
62080 
62035 

60020 
62014 
61990 
61951 



(10-19)P(2) 
(10-19)P(3) 
(10-19)P(4) 
(9-18) P(2) 
(9-18) P(4) 

(5-15) P(2) 
(5-15) P(4) 
(6-16) P(2) 
(6-16) P(4) 
(8-18) P(2) 

(7-17) P(2) 
(8-18) P(2) 
(8-18) P(4) 
(7-17) P(4) 



Wavelength, 

A vac (jLt»j) 



Frequency 
v(cm~ l ) 



Transition 



8.2.6c H 2 LASER 

TRANSITIONS IN THE (B 1 !,* - A^Zj") SYSTEM" 



0.158074 


63262 


(7-13)P(3) 


0.159606 


62654 


(3-10)P(3) 


0.160044 


62483 


— 


0.160448 


62325 


(4-ll)P(l) 


0.160750 


62208 


(6-13)P(l) 



a Additional transitions observed in the same apparatus 40. 

b See Ref. 39. Observed in a pulsed discharge in a 1.2 m long, 12 mm X 0.4 mm tube. Pressure 20-150 Torr H 2 . Maximum 
power output 1.5 kW in a 2 ns pulse. 



322 Handbook of Lasers 

TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS {Continued) 

Wavelength, Frequency „ 

A* \ / _ 1 \ 1 vein sit ion 

vac (fJ-m) v(cm *) 

8.2.6b H 2 LASER (Continued) 



0.160839 


62174 


(4-ll)P(3) 


0.160902 


62150 


(6-13)P(3) 


0.161033 


62099 


(5-12)P(l) 


0.161165 


62048 


(5-12)P(2) 


0.161318 


61989 


(5-12)P(3) 



Wavelength, Frequency ~, ._. a „ , 

v , v / - 1\ Transition Remarks 

A vac (pm) v(cm ) 



8.2.7 NO LASER 
TRANSITIONS IN THE 2 ll 1/2 /fiVZ> 2 n 3/2 ELECTRONIC GROUND STATES 







6-5 band 




5.8462 


1710.52 


2 7T 3I2 P( 7) 


b 


5.8549 


1707.98 


V 1/2 P( 8) 


b 


5.8584 


1706.95 


2 7T 3/2 P( 8) 


b 


5.8706 


1703.41 


2 7T 3/2 P( 9) 


b 


5.8789 


1700.99 


2 7T 1/2 P(10) 


b 


5.9036 


1693.88 


2 ^/2 P(12) 


b 


5.9083 


1692.53 


2 77 3/2 P(12) 


b 


5.9550 


1679.3 


2 77 1/2 P(16) 

7-6 band 


c 


5.9423 


1682.84 


2 77 3/2 P( 7) 


b 


5.9546 


1679.37 


V 3/2 P( 8) 


b 


5.9632 


1676.96 


V1/2 P( 9) 


b,c 


5.9673 


1675.81 


2 7T 3/2 P( 9) 


b 


5.9756 


1673.46 


2 77- 1/2 P(10) 


b,c 


5.9799 


1672.27 


2 77 3/2 P(10) 


b 


5.9882 


1669.96 


2 ^ 1/2 P(11) 


b 


5.9931 


1668.59 


2 77- 3/2 P(ll) 


b 


6.0010 


1666.39 


2 7T 1/2 P(12) 


b,c 


6.0054 


1665.18 


2 7T 3/2 P(12) 


b 


6.0192 


1661.36 


2 7T 3/2 P(13) 


b 


6.0267 


1659.29 


2 rr 1/2 P(14) 


b,c 


6.0324 


1657.71 


2 7T 3/2 P(14) 


b,c 


6.0402 


1655.58 


2 77 1/2 P(15) 

8-7 band 


b,c 


6.0386 


1656.0 


2 ir m P( 7) 


c 


6.0419 


1655.12 


2 77 3/2 P( 7) 


b 


6.0543 


1651.72 


2 tt 3/2 P( 8) 


b 


6.0628 


1649.40 


2 7T 1/2 P( 9) 


b,c 


6.0673 


1648.19 


2 7T 3/2 P( 9) 


b 


6.0801 


1644.71 


2 7T 3/2 P(10) 


b 


6.0884 


1642.47 


2 7T V2 P(ll) 


b,c 


6.0934 


1641.13 


2 77- 3/2 P(ll) 


b,c 


6.1015 


1638.95 


Vl/2 P(12) 


b 


6.1204 


1633.87 


2 7T 3/2 P(13) 


b 


6.1417 


1628.22 


2 7T 1/2 P(15) 


b,c 


6.1546 


1624.8 


2 77 1/2 P(16) 


c 


6.1973 


1613.6 


2 7T 1/2 P(19) 

9-8 band 


c 


6.1538 


1625.02 


2 7T 1I2 P( 8) 


b 


6.1576 


1624.00 


2 77 3/2 P( 8) 


b 


6.1663 


1621.72 


2 77 1/2 P( 9) 


b 



P (J-l/2); J has half-integer values. 

' Ref. 15. Observed in an electric discharge in NOCl-He mixtures. 
Ref. 76. Observed during flash photolysis of NOCl-He mixtures. See also Ref. 27. 



8 Molecular Gas Lasers 323 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS {Continued) 



Wavelength, Frequency Tmmition a Remarks 

Avac (jLAW) "(Cm l ) 



8.2.7 NO LASER (Continued) 



6.1792 


1618.34 


2 77 1/2 P(10) 


b 


6.1838 


1617.12 


2 7T 3/2 P(10) 


b 


6.1921 


1614.95 


2 7T 1/2 P(ll) 


b 


6.1972 


1613.63 


2 7T 3/2 P(11) 


b 


6.2055 


1611.48 


2 7T 1I2 P(12) 


b 


6.2110 


1610.06 


2 77 3/2 P(12) 


b 


6.2191 


1607.94 


2 7T 1/2 P(13) 


b 


6.2249 


1606.46 


2 7T 3/2 P(13) 

70-9 band 


b 


6.2381 


1603.06 


2 TT*I2 P( 6) 


b 


6.2511 


1599.71 


2 rr 3l2 P( 7) 


b 


6.2602 


1597.39 


2 7T 1/2 P( 8) 


b 


6.2645 


1596.30 


2 77 3/2 P( 8) 


b 


6.2778 


1592.91 


2 7T 3/2 P( 9) 


b 


6.2865 


1590.71 


2 77 1/2 P(10) 


b 


6.2913 


1589.50 


2 7T 3/2 P(10) 


b 


6.2998 


1587.36 


2 7T 1/2 P(11) 


b 


6.3051 


1586.02 


2 7T 3/2 P(11) 


b 


6.3136 


1583.88 


2 7T 1/2 P(12) 


b 


6.3191 


1582.50 


2 7T 3/2 P(12) 


b 


6.3274 


1580.43 


2 7T 1/2 P(13) 


b 


6.3336 


1578.89 


2 7T 3/2 P(13) 

11-10 band 


b 


6.3764 


1568.29 


2 7T 3I2 P( 8) 


b 


6.3894 


1565.09 


2 77 3/ 2 P( 9) 


b 


6.3980 


1562.99 


2 7T 1/2 P(10) 


b 


6.4031 


1561.74 


2 7T 3I2 P(10) 


b 


6.4262 


1556.14 


2 7T 1/2 P(12) 


b 


6.4321 


1554.71 


2 77 3/2 P(12) 


b 



Wavelength, Frequency Transition 

Avac (jim) Acm l ) 



8.2.8a N 2 LASER 
TRANSITIONS IN THE SECOND POSITIVE SYSTEM (C'EL - B 3 U g ) c - de < f 



0.337141 29661.22 

0.337178 29657.92 

0.337211 29655.03 

0.337240 29652.46 



0.357661 27959.42 

0.357713 27955.34 



0-0 band 9 



0-1 band" 



a P (J-l/2); J has half-integer values. 

b Ref. 15. Observed in an electric discharge in NOCl-He mixtures. 

c See Ref. 29. Observed in a pulsed (100 pps) discharge; pressure 4 Torr N 2 . 

d See Ref. 45. Observed in a pulsed discharge in a 0.9 m long, 3 mm i.d. tube. Pressure 1 to 2 Torr N 2 . Only the strongest 
transitions are listed in the table. A total of 35 transitions between 0.337141 f.m and 0.33659 /im in the 0-0 band, and 6 transitions 
between 0.357797 /*m and 0.357648 /im in the 0-1 band have been observed. 

e See Ref. 48. Observed in a pulsed discharge in a 1 m long, 2.8 mm i.d. tube. Pressure 1-5 Torr N 2 . A total of 17 lines 
between 0.337139 and 0.33724 pm in the 0-0 band has been observed. Measurements ±0.02 cm K 

f See Ref. 79. Observed in a pulsed discharge. Pressure ~30 Torr N 2 . A total of 28 transitions between 0.33649 /im and 
0.337143 /urn in the 0-0 band has been observed. Measurements ±0.01 cm -1 . 

8 See Ref. 45, 48 and 79 for identification. 

h See Ref. 45 for identification. 



324 Handbook of Lasers 

TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency 
A V ac (pni) a vicm' 1 )" 



Transition 1 ' 



Relative 
strength' 



Remarks 



8.2.8b N 2 LASER 
TRANSITIONS IN THE FIRST POSITIVE SYSTEM (B 3 U g - A 3 £ u + )" ,a 







4-2 band 






0.748480 


13360.41 


QiOD 


M 




0.748948 


13352.07 


Qi(9) 


S 




0.749189 


13347.76 


P Q 23 ( 7) 


M 




0.749377 


13344.42 


Qi(7) 


S 




0.749775 


13337.34 


Qi(5) 


M 




0.750363 


13326.88 


Pl(ll) 

3-1 band 


S 




0.757434 


13202.47 


— 


M 




0.758313 


13187.16 


Q 3 (13) 


S 




0.758632 


13181.62 


Q 3 (ll) 


w 




0.758855 


13177.75 


Q 3 (9) 


w 




0.759199 


13171.78 


— 


w 




0.759524 


13166.14 


Qi(15) 


w 




0.760079 


13156.52 


Qi(13) 


w 




0.760608 


13147.37 


QiOD 


M 




0.761091 


13139.03 


Qi(9) 


s 


d 


0.761195 


13137.24 


P Q 23 ( 5) 


w 




0.761535 


13131.37 


Qi(7) 


M 




0.761946 


13124.29 


Qi(5) 


M 




0.762506 


13114.65 


p Qi 2 (ll) 


W 




0.762631 


13112.50 


p Qi 2 ( 9) 


W 




0.762721 


13110.95 


P Q 12 ( 7) 
2-0 band 


W 




0.771418 


12963.14 


Q 3 ( 9) 


S 


d 


0.774602 


12909.86 


Qi(5) 


S 


d 


0.775483 


12891.87 


p Ri 3 ( 1) 
2-1 band 


W 




0.865569 


11553.10 


R 3 ( 7) 


W 




0.865730 


11550.95 


Q 3 (15) 


W 




0.866327 


11542.98 


Q 3 (13) 


M 




0.866494 


11540.76 


Q 2 (15) 


W 




0.866583 


11539.57 


Q 3 (12) 


W 




0.866810 


11536.55 


Q 3 (ll) 


S 




0.86700 


11534.0 


Q 3 (10) 


w 




0.867161 


11531.88 


Qs(9) 


s 




0.867197 


11531.41 


Q 2 (13) 


w 




0.867371 


11529.09 


Q 3 ( 7) 


w 




0.867793 


11523.48 


Q 2 (H) 


w 




0.868520 


11513.84 


Ri( 7) 


w 




0.868613 


11512.61 


Qi(13) 


M 


d 


0.869001 


11507.46 


Qi(12) 


W 




0.869375 


11502.52 


Qxdl) 


ss 


d 



3 See Ref. 48. Observed in a pulsed (1-1000 pps) discharge in a 1 m long, 2.8 mm i.d. tube. Pressure 1-5 Torr N 2 . Measure- 
ment accuracy ±0.02 cm -1 . 

b See Ref. 48. Transitions are labeled by K (the quantum number of total angular momentum apart from electron spins) 
instead of J. The superscripts O, P, R indicate AK = — 2, — 1, +1 respectively; otherwise AK = 0. The subscript indicates the 
spin states. 

c Strengths relative to strongest in each band. SS = very strong, S = strong, M = medium, W = weak. 

d See Ref. 52. Observed in a pulsed (50-150 pps) discharge (35 amperes) in a 0.40 m long, 7 mm i.d. tube. Pressure 4 Torr 
N 2 . Total peak power 0.5 watts (all lines). Other lines in the ranges 0.758 /xm to 0.762 fim and 0.770 fim to 0.775 fun were 
observed in a 1.86 m, 10 mm i.d. tube with 2 Torr pressure, 90 amperes peak current. 



8 Molecular Gas Lasers 325 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS {Continued) 



Wavelength, Frequency 



Transition* 



Relative 
strength 



8.2.8b N 2 LASER {Continued) 



Remarks 



0.869729 


11497.84 


QidO) 


M 




0.870067 


11493.37 


Qi(9) 


ss 


d 


0.870307 


11490.20 


P Q 23 ( 5) 


M 




0.870388 


11489.13 


Qi(8) 


M 




0.870494 


11487.73 


P Q 23 ( 7) 


M 




0.870570 


11486.73 


P Q 23 (11) 


W 




0.870696 


11485.06 


Qi(7) 


SS 


d 


0.870986 


11481.24 


Ch( 6) 


M 




0.871267 


11477.54 


Qi(5) 


SS 


d 


0.871533 


11474.03 


CM 4) 


W 




0.871690 


11471.97 


Pi(13) 


W 




0.871792 


11470.63 


Q,( 3) 


M 




0.871884 


11469.41 


P Q 12 (H) 


W 




0.871977 


11468.19 


Pl(ll) 


W 




0.872106 


11466.50 


P Qia( 9) 


w 




0.872193 


11465.35 


Pi(9) 


w 




0.872266 


11464.40 


P Qi 2 ( 7) 


s 




0.872374 


11462.97 


P Qi 2 ( 5) 


s 




0.872460 


11461.84 


P Qi 2 ( 3) 
1-0 band 


s 




0.883620 


11317.08 


— 


w 




0.884372 


11307.46 


Q 3 (15) 


w 




0.884662 


11303.75 




M 


d 


0.885001 


11299.42 


Q 3 (13) 


M 


d 


0.885163 


11297.36 


Q 2 (15) 


W 




0.885269 


11296.00 


Q 3 (12) 


W 




0.885504 


11293.01 


Q 3 (H) 


s 


d 


0.885704 


11290.46 


Q 3 (10) 


w 




0.885872 


11288.31 


CM 9) 


s 


d 


0.885893 


11288.04 


CM13) 


w 




0.885998 


11286.71 


Q 3 ( 8) 


w 




0.886090 


11285.53 


Q 3 ( 7) 


M 




0.886093 


11285.50 


Q 3 ( 5), R x ( 9) 


w 




0.886397 


11281.63 


R Q 2 i( 5) 


w 




0.886500 


11280.32 


Q!(15) 


w 




0.886522 


11280.04 


Qa(H) 


w 


d 


0.886941 


11274.71 


Qi(14) 


w 




0.887043 


11273.41 


Q 2 ( 9) 


w 




0.887365 


11269.32 


Q!(13) 


s 


d 


0.887775 


11264.12 


CM12) 


w 




0.888162 


11259.21 


Qidl) 


SS 


d 


0.888532 


11254.52 


Qi(lO) 


M 




0.888884 


11250.06 


CM 9) 


SS 


d 


0.889150 


11246.69 


P Q 23 ( 5) 


M 




0.889219 


11245.82 


CM 8) 


M 





a See Ref. 48. Observed in a pulsed (1-1000 pps) discharge in a 1 m long, 2.8 mm i.d. tube. Pressure 1-5 Torr N 2 . Measure- 
ment accuracy ±0.02 cm -1 . 

b See Ref. 48. Transitions are labeled by K (the quantum number of total angular momentum apart from electron spins) 
instead of J. The superscripts O, P, R indicate AK= -2, — 1, +1 respectively; otherwise AK = 0. The subscript indicates the 
spin states. 

c Strengths relative to strongest in each band. SS = very strong, S = strong, M = medium, W = weak. 

d See Ref. 52. Observed in a pulsed (50-150 pps) discharge (35 amperes) in a 0.40 m long, 7 mm i.d. tube. Pressure 4 Torr 
N 2 . Total peak power 0.5 watts (all lines). Other lines in the ranges 0.758 /*m to 0.762 /xm and 0.770 /xm to 0.775 um were 
observed in a 1.86 m, 10 mm i.d. tube with 2 Torr pressure, 90 amperes peak current. 



326 



Handbook of Lasers 



TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, 



Frequency 



Transition* 



Relative 
strength 



8.2.8b N 2 LASER (Continued) 



0.889358 


11244.06 


P Q 23 ( 7) 


M 


0.889460 


11242.78 


P Q 23 ( 9) 


W 


0.889539 


11241.78 


Qi( 7) 


ss 


0.889846 


11237.90 


QA6) 


M 


0.890137 


11234.23 


Qi(5) 


S 


0.890420 


11230.66 


Qi(4) 


W 


0.890617 


11228.17 


Pi(13) 


W 


0.890688 


11227.28 


Qi( 3) 


M 


0.890811 


11225.72 


P Ql2(H) 


W 


0.890911 


11224.47 


Pl(ll) 


W 


0.891038 


11222.87 


p Qt 2 ( 9) 


W 


0.891135 


11221.65 


Pi( 9) 


W 


0.891199 


11220.84 


P Qi 2 ( 7) 


M 


0.891308 


11219.47 


P Qi2(5),P x (7) 


M 


0.891373 


11218.65 


P Qi 2 ( 3) 
0-0 band 


W 


1.043874 


9579.70 


Qi(15) 


w 


1.044548 


9573.52 


Qi(14) 


w 


1.045189 


9567.68 


Qi(13) 


M 


1.045806 


9562.00 


Qi(12) 


w 


1.046404 


9556.54 


QiOD 


M 


1.046956 


9551.55 


Qi(io) 


W 


1.047482 


9546.70 


Qi( 9) 


M 


1.047979 


9542.18 


Qx( 8) 


W 


1.048249 


9539.72 


P Q 23 ( 7) 


S 


1.048464 


9537.79 


Qi( 7) 


M 


1.048922 


9533.60 


Qi( 6) 


M 


1.049348 


9529.73 


Qi( 5) 


S 


1.049766 


9525.93 


Q.( 4) 


M 


1.050161 


9522.35 


Qi( 3) 


W 


1.050519 


9519.10 


P Q. 2 ( 9) 


S 


1.050800 


9516.56 


P Qi 2 ( 7) 


M 


1.051005 


9514.70 


P Q. 2 ( 5) 


W 


1.051118 


9513.68 


P Q I2 ( 3) 


W 


1.052548 


9500.75 


°Ql3( 3) 


W 


1.052911 


9497.48 


°Pi 2 ( 5) 


W 


1.053382 


9493.23 


°Pi 2 ( 7) 


W 


1.053760 


9489.83 


°Pi 2 ( 9) 
0-1 band 


W 


1.230598 


8126.13 


QiOD 


W 


1.231430 


8120.64 


QidO) 


S 


1.232219 


8115.44 


Qi( 9) 


W 


1.232962 


8110.55 


Oi( 8) 


W 


1.233671 


8105.89 


Qi( 7) 


M 


1.234332 


8101.55 


Qi( 6) 


W 


1.234969 


8097.37 


Qi( 5) 


W 



Remarks 



a See Ref. 48. Observed in a pulsed (1-1000 pps) discharge in a 1 m long, 2.8 mm. i.d. tube. Pressure 1-5 Torr N, 
Measurement accuracy ±0.02 cm -1 . 

j Se <f r 1 ^ 48 ' Transitions are labeled by K (the quantum number of total angular momentum apart from electron spins) 
instead of J. The superscripts O, P, R indicate AK = - 2, -1, +1 respectively; otherwise AK = 0. The subscript indicates the 
spin states. 

e Strengths relative to strongest in each band. SS = very strong, S = strong, M = medium, W = weak. 
See Ref. 52. Observed in a pulsed (50-150 pps) discharge (35 amperes) in a 0.40 m long, 7 mm i.d. tube. Pressure 4 Torr 
N 2 . Total peak power 0.5 watts (all lines). Other lines in the ranges 0.758 urn to 0.762 urn and 0.770 urn to 0.775 am were ob- 
served in a 1.86 m, 10 mm i.d. tube with 2 Torr pressure, 90 amperes peak current. 



8 Molecular Gas Lasers 327 
TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 

Wavelength, Frequency „ „ r 

\ / ^ r -i\ Transition Reference 

8.2.8c N 2 LASER 
TRANSITIONS IN THE (aU,-^ 1 ^) SYSTEM 







2-1 band 




3.29463 


3035.24 


0(14) 


a,b 


3.30149 


3028.94 


Q(12) 


a,b 


3.30734 


3023.58 


QUO) 


a,b 


3.30989 


3021.25 


Q( 9) 


b 


3.31221 


3019.13 


Q( 8) 


a,b 


3.31426 


3017.27 


Q(7) 


b 


3.31607 


3015.62 


Q(6) 


a,b 


3.31760 


3014.23 


Q( 5) 


b 


3.31889 


3013.06 


Q(4) 


a,b 


3.32069 


3011.43 


0(2) 
1-0 band 


b 


3.45184 


2897.01 


Q(l 2) 


a,b 


3.45832 


2891.56 


QUO) 


a,b 


3.46114 


2889.22 


Q(9) 


b 


3.46368 


2887.10 


Q( 8) 


a,b 


3.46596 


2885.20 


Q(7) 


b 


3.46795 


2883.55 


Q( 6) 


a,b 


3.46967 


2882.12 


Q( 5) 


b 


3.47109 


2880.94 


Q( 4) 
0-0 band 


a,b 


8.1483 


1227.25 


QUO) 


b 


8.1827 


1222.09 


Q( 8) 


a,b 


8.2102 


1217.99 


0(6) 


a,b 



Wavelength, Frequency r~ 

s / N / -i\ Transition 

Avac \^m) v{cm ) 



8.2.8d N 2 LASER 
TRANSITIONS IN THE (v/A u - a l \\ g ) SYSTEM" 







0-0 band 


3.62349 


2759.767 


R(4) 


3.62614 


2757.752 


R( 3) 


3.62910 


2755.505 


R(2) 


3.64313 


2744.891 


Q(4) 


3.64472 


2743.697 


Q(5) 


3.64662 


2742.269 


0(6) 


3.64883 


2740.605 


0(7) 


3.65138 


2738.693 


Q( 8) 


3.65424 


2736.550 


Q(9) 


3.65745 


2734.148 


QUO) 


3.66095 


2731.530 


QUI) 


3.66483 


2728.637 


0(12) 


3.66899 


2725.549 


QU3) 


3.67352 


2722.186 


QU4) 


3.67834 


2718.618 


QU5) 



a See Ref. 59. Observed in a pulsed discharge (several hundred amperes) in a 2.25 m, 15 mm i.d. tube; pressure 0.6 Torr N 2 . 
Transitions at 8 /xm observed in a 4.25 m, 75 mm i.d. tube; pressure 0.15 Torr N 2 and 0.5 Torr Ne. 
b See Ref. 68. Observed under similar conditions." 
c Relative accuracy ±0-007 cm -1 . 
d See Ref. 62. Observed in a pulsed (15 pps) discharge; pressure 1 Torr N 2 . 



328 Handbook of Lasers 

TABLE 8-2. DIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, 



Frequency 
vicm' 1 ) 



Transition" 



Remarks 



8.2.8e N 2 LASER 
MISCELLANEOUS TRANSITIONS" 



5.35650-5.54628 
5.90723-6.24828 
6.47744-6.74441 
7.60821-8.06517 



1866.89-1803.01 
1692.84-1600.44 
1543.82-1482.71 
1314.37-1239.90 



24 lines 
24 lines 
16 lines 
20 lines 



a Unidentified. 

b See Ref. 62. Observed in a pulsed discharge in a 4.25 m, 75 mm i.d. tube; pressure 1 Torr N 2 . 

c Observed during high current pulse. 

d Observed in afterglow. 



8 Molecular Gas Lasers 
TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS 



329 



Wavelength, 
Avac i^ni) 



Frequency? 



Transition 



8.3.1a C0 2 LASER 

TRANSITIONS OF THE (10°2) - (10° J) Band" 



4.3203 
4.3249 
4.3276 

4.3549 
4.3580 
4.3612 
4.3644 
4.3677 

4.3711 
4.3745 
4.3779 
4.3814 
4.3849 



2314.65 R(17) 

2312.18 R(13) 

2310.73 R(ll) 

2296.25 P( 7) 

2294.62 P( 9) 

2292.94 P(ll) 

2291.25 P(13) 

2289.51 P(15) 

2287.76 P(17) 

2286.00 P(19) 

2284.20 P(21) 

2282.38 P(23) 

2280.53 P(25) 



3000 r 



2000- 



u 1000 




AE«I8 CM" 
00°l ^wi/\ts 

VIBRATIONAL 
ENERGY TRANSFER 



2349.16 CM' 



2330.7 CM 



-u=l 



*-v=0 



00 °0 (GROUND STATE) 



N 2 (x'Z g + ) GROUND STATE 



Fig. 8-11. Energy level diagram of N 2 and C0 2 drawn with respect to ground states N 2 (A' 1 E/, y = 0) and CO 2 (00°0), 
showing the selective excitation of C0 2 to the 00°1 level through vibrational energy transfer from N*(v = 1) and subse- 
quent laser action in C0 2 . (Ref. 74) 



Wavelength, Frequency 
Kac(prn) v(cm _1 ) 



Transition 



8.3.1b C0 2 LASER 

TRANSITIONS OF THE (00° I) - (02°0) BAND" (R BRANCH) 



9.126866 


1095.6663 


R(52) 


9.134184 


1094.7885 


R(50) 


9.141719 


1093.8862 


R(48) 


9.149471 


1092.9593 


R(46) 


9.157446 


1092.0076 


R(44) 



a See Ref. 80. Observed in Q switched C0 2 laser. Simultaneous oscillation on 10.6 /xm lines is necessary for cascade 
pumping. 

b ±0.08 cm -1 . 

c Calculated from precise frequency measurements. See Ref. 11. The absolute accuracy is about ±0.001 cm -1 or 0.00001 (im. 
For relative accuracy, all digits are significant. 

d See Refs. 12, 78 and 81 and references cited therein. 



330 Handbook of Lasers 

TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength," 



Frequency 
v(cm~ l ) 



Transition 



8.3.1b C0 2 LASER {Continued) 



9.165645 


1091.0307 


R(42) 


9.174070 


1090.0287 


R(40) 


9.182725 


1089.0014 


R(38) 


9.191612 


1087.9485 


R(36) 


9.200733 


1086.8699 


R(34) 


9.210092 


1085.7655 


R(32) 


9.219690 


1084.6352 


R(30) 


9.229530 


1083.4788 


R(28) 


9.239615 


1082.2962 


R(26) 


9.249946 


1081.0874 


R(24) 


9.260526 


1079.8522 


R(22) 


9.271358 


1078.5906 


R(20) 


9.282444 


1077.3025 


R(18) 


9.293786 


1075.9878 


R(16) 


9.305386 


1074.6465 


R(14) 


9.317246 


1073.2785 


R(12) 


9.329370 


1071.8837 


R(10) 


9.341758 


1070.4623 


R( 8) 


9.354414 


1069.0141 


R( 6) 


9.367339 


1067.5391 


R( 4) 



8.3.1c C0 2 LASER 
TRANSITIONS OF THE (00° D - (02°0) BAND" (P BRANCH) 



9.428886 


1060.5706 


P( 4) 


9.443328 


1058.9487 


P(6) 


9.458052 


1057.3002 


P( 8) 


9.473060 


1055.6251 


P(10) 


9.488355 


1053.9235 


P(12) 


9.503937 


1052.1956 


P(14) 


9.519808 


1050.4413 


P(16) 


9.535972 


1048.6608 


P(18) 


9.552428 


1046.8542 


P(20) 


9.569179 


1045.0217 


P(22) 


9.586227 


1043.1633 


P(24) 


9.603573 


1041.2791 


P(26) 


9.621219 


1039.3693 


P(28) 


9.639166 


1037.4341 


P(30) 


9.657416 


1035.4736 


P(32) 


9.675971 


1033.4881 


P(34) 


9.694831 


1031.4775 


P(36) 


9.713998 


1029.4423 


P(38) 


9.733474 


1027.3824 


P(40) 


9.753259 


1025.2983 


P(42) 


9.773356 


1023.1900 


P(44) 


9.793764 


1021.0578 


P(46) 


9.814487 


1018.9020 


P(48) 


9.835523 


1016.7227 


P(50) 


9.856876 


1014.5202 


P(52) 


9.878544 


1012.2949 


P(54) 


9.900531 


1010.0469 


P(56) 


9.922835 


1007.7765 


P(58) 


9.945458 


1005.4841 


P(60) 



a Calculated from precise frequency measurements. See Ref. 11. The absolute accuracy is about ±0.001 cm" 
jim. For relative accuracy, all digits are significant. 

b See Refs. 12, 78 and 81 and references cited therein. 



or 0.00001 



8 Molecular Gas Lasers 331 
TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength," Frequency" 



Transition 



8.3.1d C0 2 LASER 

TRANSITIONS OF THE (00°I) - (I0°0) BAND" (R BRANCH) 



10.057895 


994.2438 


R(54) 


10.066650 


993.3792 


R(52) 


10.075698 


992.4870 


R(50) 


10.085041 


991.5676 


R(48) 


10.094676 


990.6211 


R(46) 


10.104605 


989.6478 


R(44) 


10.114826 


988.6477 


R(42) 


10.125340 


987.6211 


R(40) 


10.136146 


986.5682 


R(38) 


10.147246 


985.4891 


R(36) 


10.158637 


984.3840 


R(34) 


10.170323 


983.2530 


R(32) 


10.182301 


982.0962 


R(30) 


10.194574 


980.9139 


R(28) 


10.207142 


979.7061 


R(26) 


10.220006 


978.4730 


R(24) 


10.233167 


977.2146 


R(22) 


10.246625 


975.9311 


R(20) 


10.260381 


974.6226 


R(18) 


10.274438 


973.2892 


R(16) 


10.288797 


971.9309 


R(14) 


10.303458 


970.5479 


R(12) 


10.318424 


969.1402 


R(10) 


10.333696 


967.7079 


R( 8) 


10.349277 


966.2510 


R( 6) 


10.365168 


964.7697 


R(4) 



8.3.1e C0 2 LASER 

TRANSITIONS OF THE (00°I) - (10°0) BAND" (P BRANCH) 



10.440579 


957.8012 


P(4) 


10.458220 


956.1857 


P(6) 


10.476187 


954.5458 


P( 8) 


10.494484 


952.8816 


P(10) 


10.513114 


951.1930 


P(12) 


10.532080 


949.4800 


P(14) 


10.551387 


947.7427 


P(16) 


10.571037° 


945.9810 


P(18) 


10.591035 c 


944.1948 


P(20) 


10.611385 


942.3841 


P(22) 


10.632090 


940.5488 


P(24) 


10.653156 


938.6890 


P(26) 


10.674586 


936.8045 


P(28) 


10.696386 


934.8952 


P(30) 


10.718560 


932.9611 


P(32) 



a Calculated from precise frequency measurements. See Ref. 11. The absolute accuracy is about ±0.001 cm -1 or 
0.00001 fj.m. For relative accuracy, all digits are significant. 
b See Refs. 12, 78 and 81 and references cited therein. 
c See Ref. 22. 



332 Handbook of Lasers 

TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS {Continued) 

Wavelength," Frequency _, 

\ , v / -i( Transition 



8.3.1e C0 2 


LASER {Continued) 


10.741113 


931.0022 


P(34) 


10.764052 


929.0182 


P(36) 


10.787380 


927.0091 


P(38) 


10.811105 


924.9749 


P(40) 


10.835231 


922.9153 


P(42) 


10.859765 


920.8302 


P(44) 


10.884713 


918.7197 


P(46) 


10.910082 


916.5834 


P(48) 


10.935879 


914.4212 


P(50) 


10.962110 


912.2331 


P(52) 


10.988783 


910.0188 


P(54) 


11.015906 


907.7783 


P(56) 



Wavelength, Frequency „ n , 

A vac (^) v(cm->) Transition Remarks 



8.3.1f C0 2 LASER 

TRANSITIONS OF THE (0 1 1 1) -(IPO) BAND 



10.9730 


911.33 


P(19) 


b,c 


10.9856 


910.28 


P(20) 


b,c 


10.9944 


909.55 


P(21) 


b,c 


11.0078 


908.46 


P(22) 


b,c 


11.0164 


907.74 


P(23) 


b,c 


11.0300 


906.62 


P(24) 


b,c 


11.0385 


905.92 


P(25) 


b,c 


11.0529 


904.74 


P(26) 


b,c 


11.0610 


904.08 


P(27) 


b,c 


11.0762 


902.84 


P(28) 


b,c 


11.0840 


902.20 


P(29) 


b,c 


11.0999 


900.91 


P(30) 


b,c 


11.1073 


900.31 


P(31) 


b,c 


11.1238 


898.97 


P(32) 


b 


11.1309 


898.40 


P(33) 


b 



11.1483 897.00 P(34) 



Wavelength, Frequency* „ . . 

\ ,., m \ ( -i\ Transition 



8.3.1g C0 2 LASER 

TRANSITIONS OF THE (01° I) - (03 l 0) BAND* 



10.9735 911.29 P(19) 

10.9951 909.50 P(21) 

11.0165 907.73 P(23) 

11.0300 906.62 P(24) 

11.0385 905.92 P(25) 

11.0535 904.69 P(26) 

11.0610 904.08 P(27) 

11.0760 902.85 P(28) 



a Calculated from precise frequency measurements. See Ref. 11. The absolute accuracy is about ±0.001 cm -1 or 
0.00001 /iui. For relative accuracy, all digits are significant. 

b See Ref. 31. Observed in a high current pulsed (15 pps) discharge (several hundred amperes) in a 4.25 m long, 75 mm i.d. 
tube. Pressure 2.6 Torr C0 2 - 

c See Ref. 32. Observed in a pulsed (10 pps) discharge in a 3.5 m long, 35 mm i.d. tube. Pressure 2-3 Torr CO,. 

d ±0.15 cm" 1 . 

e See Ref. 25. Observed in a cw discharge in a 1.9 m long, 18 mm i.d. tube. Pressure 1.5 Torr C0 2 . P(19) and P(38) to 
P(45) required N 2 and He. 



8 Molecular Gas Lasers 333 
TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS (Continued) 

Wavelength, Frequency" _, „ , 

\ / v / -i\ Transition Remarks 

Avac (pm) Hem x ) 

8.3.1g C0 2 LASER (Continued) 

11.0850 902.12 P(29) 

11.1000 900.90 P(30) b 

11.1070 900.33 P(31) 

11.1235 899.00 P(32) 

11.1315 898.35 P(33) 

11.1485 896.98 P(34) 

11.1555 896.42 P(35) 

11.1736 894.97 P(36) 

11.1791 894.53 P(37) 

11.1980 893.02 P(38) 

11.2035 892.58 P(39) 

11.2235 890.99 P(40) 

11.2295 890.51 P(41) 

11.2495 888.93 P(42) 

11.2545 888.53 P(43) 

11.2770 886.76 P(44) 

11.2804 886.49 P(45) 

Wavelength, Frequency „ D , 

\ t •> ' t -\( Transition Remarks 

Avac (/aw) v(cm l ) 

8.3-lh C0 2 LASER 
MISCELLANEOUS TRANSITIONS 



13.144 
13.154 
13.159 


760.78 
760.21 
759.89 


Q Branch (l^MOS'O)? 


d 


13.541 


738.51 


Q Branch (21 '0)-(12 2 0)? 


d 


16.585 
16.597 


602.96 
602.51 


Q Branch (M^M^O)? 


d 


17.023 
17.029 
17.036 
17.048 


587.43 
587.25 
587.00 
586.59 


Q Branch (034)-(02 2 l)? 


d 


17.370 
17.376 
17.390 


575.71 
575.49 
575.05 


Q Branch (24°0)-(23 1 0)? 


d 



Wavelength, Frequency rr 

x /• v i -\\ Transition 

Avac (fJ-m) v(cm l ) 



8.3.1i CO! 8 LASER 

TRANSITIONS OF THE (00° I) - (J0°0) BAND' 



9.341 


1070.6 


P(18) 


9.355 


1069.0 


P(20) 


9.369 


1067.4 


P(22) 


9.383 


1065.8 


P(24) 


9.397 


1064.2 


P(26) 



a ±0.15 cm" 1 . 
b Strongest line. 

c See Ref. 32. Observed in a pulsed (10 pps) discharge in a 3.5 m long, 35 mm i.d. tube. Pressure 2-3 Torr C0 2 . Identi- 
fications are tentative. 

d Strongest line in group. 

e See Ref. 85. Observed in a mixture of C0 2 8 and H 2 18 . 



334 Handbook of Lasers 

TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, 



Frequency 
v{cm~ l ) 



Transition 



Relative 
strength 



8.3.2. CS 2 LASER 

TRANSITIONS IN THE (02° 1) - (12°0) BAND bc 



Wavelength, 

Avac (H 



Frequency 
v(cm~ l ) 



12.85 


778.2 


71.899 


139.084 


73.101 


136.796 


76.093 


131.418 


77.001 


129.868 



11.4823 


870.90 


P(28) 


0.18 


11.4893 


870.38 


P(30) 


1.0 (P> lOmW) 


11.5962 


869.85 


P(32) 


0.27 


11.5031 


869.33 


P(34) 


0.35 


11.5099 


868.82 


P(36) 


0.18 


11.5166 


868.31 


P(38) 


0.25 


11.5237 


867.80 


P(40) 


0.12 


11.5307 


867.27 


P(42) 


0.16 


11.5376 


866.73 


P(44) 


<0.1 


11.5446 


866.20 


P(46) 


0.50 



Vibrational 
transition 



Rotational 
transition 



Peak d 
watts 



Remarks 



8.3.3a HCN LASER" 





e 


0.3 


f 


0.008 


f 


0.005 


f 


0.003 


f 



I'O 



J=I2 



J=ll 



J = I0 




J = 8 



Fig. 8-12. Partial energy level diagram of HCN molecule showing far infrared laser transitions. (Ref. 74) 



a ±0.02 cm" 1 . 

b See Ref. 73. Observed in a discharge-free interaction region 2 m long and 25 mm i.d., into which excited N, is flowed 
Pressure 0.1 Torr CS 2 , 2 Torr N 2 . Continuous laser. 

c See Ref. 51 for identifications. Previous identification [see Ref. 63] was made in the (001)-(100) band. 

d See Refs. 66 and 82 and references cited therein for details. All transitions observed in a pulsed discharge. The unidentified 
transitions may not belong to HCN. Typical mixtures: CH 4 +NH 3 , CH 4 +N 2 , CH 3 CN, (CH 3 ) 2 NH, HCN or ICN (plus 
impurities). 

e See Ref. 84. 

f See Ref. 66. Observed in a pulsed (3 pps) discharge (200-900 amperes) in a 6.2 m long, 78 mm i.d. tube; pressure 0.2-0.3 
Torr dimethylamine [(CH 3 ) 2 NH]. 



8 Molecular Gas Lasers 335 
TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS (Continued) 





Wavelength, 


Frequency 


Vibrational 


Rotational 


Peak" 


Remarks 




Avac (pm) 


v(cm~ l ) 


transition 


transition 


watts 








8.3.3a HCN LASER" {Continued) 








81.554 


122.618 






0.1 


b 




96.401 


103.733 






0.2 


b 




98.693 


101.325 






0.8 


b 




101.257 


98.759 






0.2 


b 




112.066 


89.233 






0.2 


b 




116.132 


86.109 






0.5 


b 




126.164 


79.262 


(WOhiOS^O) 


R(26) 


3. 


b,c,d 




128.629 


77.743 


(12 2d 0)-(05 ld 0) 


R(25) 


9 


b,c,d,e 




130.838 


76.430 


(12°0)-(05 lc 0) 


R(25) 


4 


b,c,d 




134.932 


74.111 


(12°0)-(05 If 0) 


R(24) 


0.8 


b,c,d 




201.059 


49.737 






0.05 


b,c 




211.001 


47.393 






0.2 


b,c,e 




222.949 


44.853 






0.08 


b,c 




284 


35.2 


(ll lc 0)-(H lc 0) 


ROD 




e,f 




309.7140 


32.28785 


(ll lc 0)-(H lf 0) 


R(10) 


0.4 


b,c,d,e,f 




310.8870 


32.16603 


(ll IC 0)-(04°0) 


R(10) 


1. 


b,c,d,e,f 




335.1831 


29.8344 


(04°0)-(04°0) 


R( 9) 




d,e : f 




336.5578 


29.71258 


(H ,c 0)-(04 o 0) 


R( 9) 


0.6 


b,c,d,e,f,g,h 




372.5283 


26.84360 


(04°0)-(04°0) 


R( 8) 


0.6 


b,c,d,e,f 




538.2 


18.580 








a,h 




545.4 


18.335 








a 




676 


14.79 








a 




773.5 


12.928 








a 




Wavelength, 


Frequency 


Vibrational 


Rotational 


Peak 


Remarks 




Avac (H-m) 


v(cw _1 ) 


transition 


transition 


watts 








8.3.3b DCN LASER' 


j 








181.789 


55.009 


(22°0)-(22°0) 


R(22) 


0.1 


i 




189.9490 


52.6457 


(22°0)-(09 lc 0) 


R(21) 


0.1 


i,k 




190.0080 


52.6294 


(22°0)-(22°0) 


R(2l) 




j,k 




194.7027 


51.3604 


(22°0)-(09 lc 0) 


R(20) 


0.02 


i,k 




194.7644 


51.3441 


(09 lf 0)-(09 lc 0) 


R(20) 




j,k 




204.3872 


48.9267 


(09 ,c 0)-(09 lf 0) 


R(19) 


0.04 


i,k 








Wavelength, Frequency 


Peak 












Ayac (pm) v(cm~ x ) 


watts 












8.3.3c HCN 15 LASER' 












110.240 90.711 


1. 












113.311 88.253 


0.1 












138.768 72.063 


1. 












165.150 60.551 


1. 







a See Refs. 66 and 82 and references cited therein for details. All transitions observed in a pulsed discharge. The unidentified 
transitions may not belong to HCN. Typical mixtures: CH 4 +NH 3 , CH 4 +N 2 , CH 3 CN, (CH 3 ) 2 NH, HCN or ICN (plus 
impurities). 

b See Ref. 66. Observed in a pulsed (3 pps) discharge (200-900 amperes) in a 6.2 m long, 78 mm i.d. tube; pressure 2-0 3 
Torr dimethylamine [(CH 3 ) 2 NH]. 

c See Ref. 57. 

d See Refs. 65 and 50 for identification. 

e Transitions also observed in a continuous discharge. 

f See Ref. 33. Absolute frequency measurement. 

g See Ref. 26. 

h Splitting of this line has been observed by some authors, see Ref. 82. 

' See Refs. 66 and 82 and references cited therein for details. All transitions observed in a pulsed discharge in mixtures of 
D 2 and BrCN or CD 4 and ND 3 . 

j See Ref. 65 for identifications and Ref. 34 for absolute frequency measurements of cw lines. 

k Observed in a cw discharge. 

1 See Ref. 66. Observed in a pulsed discharge (200-900 amperes) in a 6.2 m long, 78 mm i.d. tube. Transitions unidentified. 



336 



Handbook of Lasers 



•s-f 




$ 



(,_W0) AQH3N3 



o 


gy-ie 

e lin 

vels 


10 


^ F H 




w «•« 








rt O 








^^.a 




m «-r. 




.9 5 












y js 



8 Molecular Gas Lasers 337 
TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, Frequency Vibrational Rotational Peak 

A vac (/xm) licm' 1 ) transition transition watts"-" Remarks 



8.3.4a H 2 LASER' 



2.279 


4387.60 


- 


_ 




d,e 


4.77 


2096. 


- 


_ 




f 


7.458 


1340.70 


(020)-(010) 


44i -5so 




g 


7.596 


1316.38 


(020)-(010) 


550 -661 




g 


7.7G9 


1297.19 


(020)-(010) 


661 -740 




d,g 


11.83 


845.3 


- 


_ 




f 


11.96 


836.1 


- 


_ 




f 


16.932 


590.60 


(OIO)-(OIO) 


13ll, 2-12io, 3 


0.02 


a,h 


23.13 


432.3 


(020M020) 


963-854 


0.04 


b,d 


23.365 


427.99 


(100)-(020) 


945-854 


0.10 


a 


24.966 


400.54 


(100)-(020) 


844-75 3 




d,e,i 


26.660 


375.09 


(100)-(020) 


743-652 


0.50 


a,h 


27.9707 


357.516 


(001)-(020) 


633-550 


3.0 


aj,k 


28.054 


356.46 


(020)-(020) 


661-550 




a 


28.270 


353.73 


(100)-(020) 


808-/35 


0.60 


a,l 


28.356 


352.66 


(020M020) 


844—735 


0.01 


a,h 


28.451 


351.48 


(100)-(020) 


642-551 




d,e,i 


32.924 


303.73 


(020M020) 


5 5 0^41 


0.4 


a,h 


33.029 


302.76 


(100M020) 


5i4— 441 


7.0 


a,h,j 


34.60 


289.02 


- 


- 


0.35 


b,m 


35.017 


285.58 


(100M100) 


734-625 




a,h,i 


35.833 


279.07 


(100M020) 


12i,i2-ll29 


0.10 


a,h,i 


36.606 


273.18 


(oiomoio) 


13n, 2 - 13io, 3 


0.009 


a,h,i 


37.848 


264.21 


(100M020) 


12o, 12— H39 


0.003 


a,h,i 


38.086 


262.56 


- 


- 




a,h 


39.695 


251.92 


(001)-(020) 


744—66 1 


0.10 


a,h 


40.45 


247.2 


(100)-(020) 


13i t 13 — 122, 10 




d,e,i 


40.638 


246.08 


(020)-(020) 


441—330 


0.01 


a,h 


42.51 


235.24 


- 


- 


0.006 


b,m 


45.517 


219.70 


- 


_ 


0.007 


a,h 


45.91 


217.82 


- 


- 


0.006 


b,m 


47.244 


211.67 


(020)-(020) 


963 _ 9s4 


0.08 


a,h,j 


47.39 


211.01 


- 


- 


0.024 


d,b 


47.468 


210.67 


(001H020) 


633-652 


0.06 


a,h,j 


47.687 


209.70 


(020)-(020) 


66 1-652 


0.04 


a,h,j 


48.19 


207.5 


(100)-(020) 


945—954 


0.028 


b,m 


48.676 


205.44 


- 


- 


0.07 


a,h 


49.06 


203.83 


(100)-(020) 


743 _ 7s2 


0.001 


b,d 


53.910 


185.49 


- 


- 


0.0008 


a,h 


54.853 


182.31 


- 


- 




d,e 


55.000 


181.82 


(020)-(020) 


652-643 




d,e,i 


55.088 


181.53 


(020)-(020) 


5so _ 54i 


0.06 


a,h,j 


57.659 


173.43 


(100)-(020) 


919—844 


0.02 


a,h 


57.799 


173.01 


(020)-(020) 


9s4 _ 945 




d,e,i 


66.880 


149.52 


- 


_ 




d,e 


66.903 


149.45 


- 


- 




d,e 


67.169 


148.88 


(020M020) 
or(100)-(020) 


441^32 
62 5—550 


0.01 


a,h,i 



a See Ref. 54. 

b See Ref. 42. 

c See Ref. 7 and references cited therein for details. All transitions observed in a pulsed discharge in H,0 

d See Ref. 23. 2 ' 

e Line at this position has not been verified. 

f See Ref. 84. 

g See Ref. 36. 

h Wavelength from Ref. 7. 

1 Questionable identification. 

J Transitions also observed in a continuous discharge in H 2 0. 

k Wavelength from Ref. 21. 

1 Wavelength from Ref. 67. 

m Frequency selective resonator necessary. 



338 



Handbook of Lasers 



TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS {Continued) 



Wavelength, 
Avac (fm) 



Frequency 
vicm -1 ) 



Vibrational 
transition 



Rotational 
transition 



Peak 
watts"-" 



Remarks 



8.3.4a H 2 LASER {Continued) 



68.344 


146.32 


(020)-(020) 


541-532 




d,e,f 


72.856 


137.26 


(100)-(020) 


817-844 




d,g 


73.401 


136.24 


(lOO)-(lOO) 


817-808 


0.002 


a,g 


78.443 


127.481 


(100M020) 


808-835 


0.007 


a,h,U 


79.087 


126.44 


(020)-(020) 


844-835 


0.006 


a,g,h,j 


85.564 


116.87 


(100)-(020) 


7s2 _ 761 




d,f,g,j 


86.478 


115.64 


(lOOMioo) 


954-945 




d,e,f 


87.323 


114.52 


- 


- 




d,e 


87.469 


114.32 


(100)-(020) 


853-862 




d,e,f 


89.772 


111.39 


(100)-(020) 


954-963 


0.006 


a,g 


89.947 


111.18 


- 


- 




d,e 


90.565 


110.42 


- 


- 




d,e 


115.32 


86.72 


(020)-(020) 


835-826 


0.0007 


a,g,h 


118.591 


84.323 


(001)-(020) 


642-66 1 


0.001 


a,g,h 


120.08 


83.28 


(OOl)-(OOl) 


642-633 




a 


220.230 


45.407 


(100H020) 


523-550 




g,h,k 



Wavelength, 



Frequency 



Avac (pm) 1 v(cm *)' 



Vibrational 
transition 



Rotational 
transition 



Remarks 
(strength)" 



8.3.4b H 2 18 LASER" 



25.162 


397.42 


(100)-(020) 


845-752 


0.38 


26.595 


376.01 


(100)-(020) 


744-65 1 


0.38 


28.295 


353.42 


(100)-(020) 


643-550 


1.00 


33.308 


300.23 


(020)-(020) 


550-441 


0.08 


35.383 


282.62 


(100M020) 


12i, 12-H29 


0.08 


48.366 


206.76 


(100M020) 


643-652 


0.28 


48.604 


205.74 


(020H020) 


66 1-652 


0.24 


48.765 


205.07 


(100)-(020) 


744—753 


0.05 


49.430 


202.31 


(100)-(020) 


845-854 


0.08 


56.129 


178.16 


(020)-(020) 


5 5 0—541 


0.04 



Wavelength, 
Avac (pm) 



Frequency 
v(c/w -1 ) 



Vibrational 
transition 



Rotational 
transition 



Peak 
watts" 



Remarks 



8.3.4c D 2 LASER" 



26.36 


379.36 


- 


- 




b 


33.896 


295.02 


(100M020) 


13 5 9-12 6 6 


0.30 


a,f,g 


35.081 


285.05 


(100M020) 


12 5 8-ll65 


0.30 


a,f,g 


36.096 


277.04 


(100M020) 


11 56-10 65 




d,e 



a See Ref. 54. 

b See Ref. 42. 

c See Ref. 7 and references cited therein for details. All transitions observed in a pulsed discharge in H 2 0. 

d See Ref. 23. 

e Line at this position has not been verified. 

f Questionable identification. 

8 Wavelength from Ref. 7. 

h Transitions also observed in a continuous discharge in H 2 0. 

1 Wavelength from Ref. 21. 

J Lines at 117.04, 117.22, 117.40, 126.66, 126.87, 126.95, 127.07, 127.24, 127.73, 127.92, 128.08, and 128.31 cm" 1 have 
been reported (Refs. 23 and 41), but are thought to be spurious responses associated with transitions at 116.87, 126.44 and 127.48 
cm" 1 (see Ref. 7). 

k See Ref. 61. 

1 Accuracy ±0.01 %. 

m Strongest line approximately 5 mW peak power. 

n See Ref. 7. Observed in a pulsed discharge in a 3 m long, 75 mm i.d. tube in H 2 18 . 

See Ref. 7 and references cited therein for details. All transitions observed in a pulsed discharge in D 2 0. 



8 Molecular Gas Lasers 339 



.i c 
« 2 

c/J 4) 




340 



Handbook of Lasers 







8 Molecular Gas Lasers 341 
TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS {Continued) 



Wavelength, Frequency 
A vac (pm) vicm' 1 ) 



Vibrational 
transition 



Rotational 
transition 



Peak 
watts" 



Remarks 



8.3.4c D 2 LASER" (Continued) 



36.324 


275.30 


(100M020) 


11 57-10 6 4 


0.40 


a,c 


36.526 


273.78 


(020H020) 


11 75-10 6 4 


0.04 


a,c 


37.788 


264.63 


(100H020) 


1055-964 




a,c 


37.860 


264.13 


(100M020) 


10 5 6-9 6 3 




c,d 


39.53 


252.97 


(100M020) 


955-864 




e 


40.994 


243.94 


(020H020) 


10 6 4-9 55 


0.02 


a 


41.79 


239.28 


(100M020) 


1266-H75 




d,f,g 


48.80 


204.92 


_ 


_ 




e 


50.71 


197.20 


_ 


_ 




e 


54.73 


182.72 


— 


_ 




e 


56.830 


175.96 


(100M020) 


16o, 16-153, 13 


0.10 


a,c,g 


61.182 


163.45 


- 


_ 




d,f 


71.944 


138.99 


(100H020) 


11 57-U 66 


0.008 


a,c,h 


72.427 


138.07 


(020M020) 


10 7 4-10 6 5 
or 10 7 3-10 6 4 


0.02 


a,c,g 


72.757 


137.44 


(020M020) 


1175-1166 


0.08 


a,c 


73.341 


136.35 


(100H020) 


12 5 8-12 6 7 


0.04 


a,c,g 


74.526 


134.18 


(100M020) 


13 5 9-13 6 8 


0.04 


a,c,g 


76.305 


131.05 


- 


- 


0.009 


a 


78.16 


127.94 


- 


_ 




e 


83.730 


119.43 


(020H020) 


10 6 5-10 5 6 




d,f,g 


84.111 


118.89 


(020H020) 


H66-H57 


0.02 


a 


84.284 


118.65 


(100M020) 


12i, 12— H47 


0.05 


a,c,h 


99.00 


101.01 


- 


_ 




e 


103.33 


96.78 


- 


_ 




e 


107.731 


92.823 


(100M020) 


1166-H 75 


0.01 


a,c,h 


107.91 


92.67 


(ioohioo) 


1368 - 13s9 




d,f,g 


108.88 


91.84 


(100H020) 


1165-1174 




e,g 


110.49 


90.51 


(100H020) 


12 6 6-12 7 5 




d,f,g 


111.74 


89.49 


(100)-020) 


1 3 68 -l 3 77 




d,f,g 


170.08 


58.80 


(020M020) 


H47-H38 




b,c 


171.67 


58.25 


(100H020) 


Ho,ll-ll38 




c,h,i 


218.5 


45.77 








i 



Wavelength, 11 
Avac (.[im) 



Frequency 
vicm' 1 ) 



Relative 
strength 



8.3.5 H,S LASER' 



33.48 


298.7 


0.6 


33.65 


297.2 


480 


49.63 


201.5 


1 


52.41 


190.8 


60 


56.86 


175.9 


60 


60.31 


165.8 


200 


61.52 


162.6 


1000 


73.54 


136.0 


0.2 


80.52 


124.2 


220 


83.45 


119.8 


1000 



a See Ref. 54. 

b See Ref. 7 and references cited therein for details. All transitions observed in a pulsed discharge in D,0 
c Wavelength from Ref. 7. 
d See Ref. 23. 
e See Ref. 42. 

f Line at this position has not been verified. 
* Questionable identification. 

h Transitions also observed in a continuous discharge in D 2 0. 
1 See Ref. 61. 
j See Ref. 47. 
k A±i%. 

1 See Ref. 38. Observed in a pulsed (2 pps) discharge in H 2 S. Pressure 0.15 Torr. Laser duration 20-100 us, delay after 
current pulse 20-30 us. 



342 Handbook of Lasers 

TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS {Continued) 



Wavelength," 
A vac (pm) 



Frequency 
v(cm _1 ) 



Relative 
strength 



8.3.5 H 2 S LASER 6 {Continued) 



92.03 


108.7 


0.1 


96.41 


103.7 


3 


103.3 


96.8 


125 


108.8 


91.9 


7 


116.8 


85.6 


4 


126.2 


79.2 


2 


129.1 


77.4 


4 


130.8 


76.4 


1 


135.5 


73.8 


2 


140.6 


71.1 


10 


162.4 


61.6 


560 


192.9 


51.8 


20 


225.4 


44.4 


1000 



Wavelength, 
Avac ((J-ni) 



Frequency 
v(cw _1 ) 



Transition 



Remarks 



8.3.6a N 2 LASER 

TRANSITIONS OF THE (00° I) - (10°0) BAND (R BRANCH) 



10.3456 


966.59 


R(35) 


d 


10.3532 


965.88 


R(34) 


d 


10.3609 


965.16 


R(33) 


d 


10.3687 


964.44 


R(32) 


d 


10.3765 


963.72 


R(31) 


d 


10.3843 


962.99 


R(30) 


d 


10.3922 


962.26 


R(29) 


d 


10.4001 


961.53 


R(28) 


d 


10.4081 


960.79 


R(27) 


d 


10.4161 


960.05 


R(26) 


d 


10.4242 


959.31 


R(25) 


d 


10.4323 


958.56 


R(24) 


d 


10.4405 


957.81 


R(23) 


d 


10.4487 


957.06 


R(22) 


d 


10.4570 


956.30 


R(21) 


d 


10.4653 


955.54 


R(20) 


d,e 


10.4737 


954.77 


R(19) 


d,e 


10.4821 


954.01 


R(18) 


d,e 


10.4906 


953.24 


R(17) 


d,e 


10.4991 


952.46 


R(16) 


d,e 


10.5077 


951.69 


R(15) 


d,e 


10.5163 


950.90 


R(14) 


d,e 


10.5250 


950.12 


R(13) 


d,e 


10.5337 


949.33 


R(12) 


d,e 


10.5425 


948.54 


R(ll) 


d,e 


10.5513 


947.75 


R(10) 


d 


10.5602 


946.95 


R( 9) 


d 



a A± 1% 

b See Ref. 38. Observed in a pulsed (2 pps) discharge in H 2 S. Pressure 0.15 Torr. Laser duration 20-100 /as, delay after 
current pulse 20-30 /ms. 

Calculated from v= 938.79 + 0.83282 m-0.00168 m 2 , with w = 7+ 1. See Ref. 71. 

d See Ref. 60. Observed in a continuous discharge N 2 0-N 2 mixtures. Frequency selective resonator. 

e See Ref. 30. 



8 Molecular Gas Lasers 343 
TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS (Continued) 



2500r 



2000 



1500 



- VIBRATIONAL ENERGY TRANSFER 

2330.7 CM" 

+ , 



AE« 107 CM' 



1055.55 CM 



1000 



500 




2+02°0 



00°0 (GROUND STATE) 



GROUND STATE 

Fig. 8-16. Pertinent parts of the energy level diagram of N 2 and 
N 2 drawn with respect to the ground states N 2 (A' 1 Sj 1 ', v = 0) and 
N 2 O(00°0), showing vibrational energy transfer and subsequent laser 
action in N 2 0. (Ref. 74) 



Wavelength," Frequency" 
A vac (|U.»0 v(cm~ l ) 



Transition 



Remarks 



8.3.6a N 2 LASER {Continued) 



10.5692 


946.15 


R( 8) 


b 


10.5781 


945.35 


R( 7) 


b 


10.5872 


944.54 


R( 6) 


b 


10.5963 


943.73 


R( 5) 


b 


10.6054 


942.91 


R(4) 


b 


10.6146 


942.09 


R( 3) 


b 


10.6239 


941.27 


R( 2) 


b 


10.6332 


940.45 


R( 1) 


b 



10.6426 939.62 R( 0) c 

8.3.6b N 2 LASER 
TRANSITIONS OF THE (00° J) - (/0°0) BAND {P BRANCH) 



10.6614 


937.96 


P( 1) 


c 


10.6710 


937.11 


P( 2) 


b 


10.6806 


936.28 


P( 3) 


b 


10.6903 


935.43 


P( 4) 


b 


10.6999 


934.58 


P( 5) 


b 



a Calculated from v = 938.79 + 0.83282 m- 0.00168 m 2 , withm = 7+ 1. See Ref. 71. 
b See Ref. 60. Observed in a continuous discharge in N 2 0-N 2 mixtures. Frequency selective resonator. 
c See Ref. 20. Observed in a continuous discharge. Frequency selective resonator. Also 24 transitions tentatively identified 
as P and R branch of (001)-(02°0) observed. 



344 Handbook of Lasers 

TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength," 
Avac (fim) 



Frequency" 
v(cm ~ ' ) 



Transition Remarks 



8.3.6b N z O LASER {Continued) 



Wavelength, 
Avac i/J-m) 



Frequency 
v^cm -1 ) 



Transition 



10.7097 


933.73 


P( 6) 


b 


10.7195 


932.88 


P( 7) 


b 


10.7294 


932.02 


P( 8) 


b 


10.7393 


931.16 


P( 9) 


b 


10.7493 


930.29 


P(10) 


b 


10.7593 


929.43 


POD 


b 


10.7694 


928.55 


P(12) 


b,c 


10.7796 


927.68 


P(13) 


b,c 


10.7898 


926.80 


P(14) 


b,c 


10.8000 


925.92 


P(15) 


b,c 


10.8104 


925.03 


P(16) 


b,c 


10.8208 


924.15 


P(17) 


b,c 


10.8312 


923.25 


P(18) 


b,c 


10.8418 


922.36 


P(I9) 


b,c 


10.8523 


921.46 


P(20) 


b,c,d 


10.8629 


920.56 


P(21) 


b,c,d 


10.8736 


919.65 


P(22) 


b,c,d 


10.8844 


918.75 


P(23) 


b,c,d 


10.8952 


917.83 


P(24) 


b,c,d 


10.9061 


916.92 


P(25) 


b,c,d 


10.9170 


916.00 


P(26) 


b,c,d 


10.9280 


915.08 


P(27) 


b,c,d 


10.9390 


914.16 


P(28) 


b,c,d 


10.9501 


913.23 


P(29) 


b,c 


10.9613 


912.29 


P(30) 


b,c 


10.9726 


911.36 


P(31) 


b,c 


10.9839 


910.42 


P(32) 


b,c 


10.9953 


909.48 


P(33) 


b,c 


11.0067 


908.53 


P(34) 


b,c 


11.0182 


907.58 


P(35) 


b,c 


11.0298 


906.63 


P(36) 


b,c 


11.0415 


905.68 


P(37) 


b,c 



8.3.7a OCS LASER 

TRANSITIONS OF THE (00° 1) - (10°0) BAND" 



.2388 


1213.76 


R(26) 


.2416 


1213.35 


R(25) 


.2439 


1213.02 


R(24) 


2518 


1211.86 


R(21) 


2543 


1211.48 


R(20) 


2571 


1211.08 


R(19) 


2595 


1210.73 


R(18) 


2623 


1210.32 


R(17) 



a Calculated from v = 938.79 + 0.83282 m - 0.00168 m 2 , with m = — /. See Ref. 71. 
b See Ref. 60. Observed in a continuous discharge N 2 0-N 2 mixtures. Frequency selective resonator. 
c See Ref. 71. 
d See Ref. 55. 

e See Ref. 14. Observed in a pulsed (16 pps.) discharge (70 amperes maximum) in a 2 m long, 32 mm i.d. tube. Pressure 0.3 
Torr OCS, 0.8-6 Torr He. Lasing delay 20-60 (is, lasing duration 30 /*s. CO transitions at 5 pm observed simultaneously. 



8 Molecular Gas Lasers 345 
TABLE 8-3. TRIATOMIC MOLECULAR GAS LASERS (Continued) 



Wavelength, 

Avac (/ATM) 



Frequency 
v(cm~ l ) 



Transition 



8.3.7a OCS LASER (Continued) 

8.2645 
8.2673 

8.3625 
8.3654 
8.3685 
8.3715 
8.3746 

8.3779 
8.3809 
8.3839 
8.3870 
8.3900 

8.3930 
8.3962 
8.3999 
8.4024 
8.4055 

8.4085 
8.4117 
8.4146 
8.4178 
8.4213 

8.4243 1187.04 P(38) 

8.3.7b OCS LASER 
MISCELLANEOUS TRANSITIONS" 



1209.99 


R(16) 


1209.59 


R(15) 


1195.82 


P(18) 


1195.40 


P(19) 


1194.98 


P(20) 


1194.52 


P(21) 


1194.09 


P(22) 


1193.62 


P(23) 


1193.19 


P(24) 


1192.76 


P(25) 


1192.32 


P(26) 


1191.89 


P(27) 


1191.46 


P(28) 


1191.02 


P(29) 


1190.49 


P(30) 


1190.14 


P(31) 


1189.70 


P(32) 


1189.27 


P(33) 


1188.82 


P(34) 


1188.40 


P(35) 


1187.95 


P(36) 


1187.46 


P(37) 



123 
132 



81.3 

75.8 



Wavelength,* 
A vac (fim) 



Frequency 
v(cm~ l ) 



Remarks 



8.3.8 S0 2 LASER 



140.85 


70.99 


c,d,e,f 


151.16 


66.16 


c,e 


192.67 


51.90 


c,d,f 


215.27 


46.45 


c,e 



a See Ref . 38. Observed in a pulsed (2 pps or less) discharge. Pure OCS or with N 2 , He, CO or CO + He buffer. 

b Transition unidentified. 

c See Ref. 37. Observed in a pulsed (13 pps) discharge (90 amperes peak) in a 2 m long, 76 mm i.d. tube. Pressure 0.4Torr 
S0 2 , 0.4 Torr He. Wavelength ±0.05 pm. 

d See Ref. 19. Observed in a continuous discharge (0.15 amperes) in a 2.5 m long, 56 mm i.d. tube. Pressure 2.1 Torr S0 2 , 
1.5 Torr He. 

e See Ref. 38. Observed in a pulsed (2 pps) discharge. He, N 2 or 2 buffer. 

f See Ref. 37. Observed in a continuous discharge (0.4 amperes) in a 2 m long, 76 mm i.d. tube. Pressure 0.4 Torr S0 2 , 
0.4 Torr He. 



346 Handbook of Lasers 

TABLE 8-4. OTHER POLYATOMIC MOLECULAR GAS LASERS 



Wavelength, Frequency 

A vac iy-ni) v(cm~ l ) 



Transition 



8.4.1 CH 3 F LASER 

PURE ROTATIONAL TRANSITIONS" 



v = 
451.924 22.1276 R(12),K = 2 

451.903 22.1286 R(12),K=1 

v 3 = l 
496.105 6 20.1570 R(10),K = 2 

496.072 6 20.1584 R(10),K=1 

541.147 18.4793 R(11),K = 2 

541.113 18.4804 R(11),K=1 



Wavelength, Frequency „ , c _ 

Avac(/xm) Kcm- 1 ) Strength Remarks 



8.4.2 CH 3 OH LASER 
PURE ROTATIONAL TRANSITIONS' 1 



70.6 


141.6 


L 


e 


118.8 


84.18 


H 


f 


164.3 


60.86 


M 


g 


170.6 


58.62 


H 


f 


185.5 


53.91 


VL 


e 


190.8 


52.41 


VL 


e 


193.2 


51.76 


VL 


h 


198.8 


50.30 


L 


h 


202.4 


49.41 


M 


f 


223.5 


44.74 


M 


g 


237.6 


42.09 


L 


e 


253.6 


39.43 


L 


e 


254.1 


39.35 


M 


e 


263.7 


37.92 


M 


e 


264.6 


37.79 


M 


e 


278.8 


35.87 


VL 


h 


292.2 


34.22 


VL 


h 


292.5 


34.19 


VL 


e 


369.1 


27.09 


H 


g 


392.3 


25.49 


H 


f 


417.8 


23.93 


M 


f 


570.5 


17.53 


H 


g 


699.5 


14.30 


VL 


e 



a See Ref. 10. Observed in a 0.93 m long, 47.5 mm i.d. tube, pressure up to 1 Torr CH 3 F. Optically pumped by a O-switched 
C0 2 laser at 9.5524 /am [00°l-02°0, P(20)]. 

b See Ref. 13. Observed in a 0.77 m long, 47.7 mm i.d. tube pressure 0.03-0.13 Torr CH 3 F. Optically pumped by a 10 W 
cw C0 2 laser at 9.5524 /xm [00°l-02°0, P(20)]. 

c VL = very low, L = low, M = medium, H = high (several milliwatts). 

d See Ref. 13. Observed in a 0.77 m long, 47.5 mm i.d. tube, pressure 0.03-0.13 Torr CH 3 OH (methyl alcohol). Transitions 
are in the C-O stretch mode (v s ). 

e Optically pumped by a 10 W, cw C0 2 laser at 9.6760 ^m [00°l-02°0, P(34)]. 

f Optically pumped by a 10 W, cw C0 2 laser at 9.6948 ^m [00°l-02°0, P(36)]. 

8 Optically pumped by a 10 W, cw C0 2 laser at 9.5198 /xm [00°l-02°0, P(16)]\ 

h Optically pumped by a 10 W, cw C0 2 laser at 9.7140 /tm [00°l-02°0, P(38)]. 



8 Molecular Gas Lasers 347 
TABLE 8-4. OTHER POLYATOMIC MOLECULAR GAS LASERS (Continued) 

Wavelength, Frequency Pump n , 

\ / \ i -i\ „ C- Remarks 

Avac \^nt) v(cm ) transition 

8.4.3 H 2 C : CHCI LASER 

PURE ROTATIONAL TRANSITIONS" 

386.0 25.91 CH wagging b 

507.7 19.70 CH wagging b 

634.4 15.76 CH 2 rocking c 



Wavelength, Frequency _ . . d _ . 

\ i "\ i - 1 \ Transition" Remarks 

Ayac (/J-m) v{cm ') 



8.4.4 NH 3 LASER 

TRANSITIONS IN THE (0 3 s 0) - (0 2" 0) BAND ef 



14.78 


676.6 






f,g 


15.04 


664.9 






f 


15.08 


663.1 






f 


15.41 


648.9 






f 


15.47 


646.4 






f,g 


18.21 


549.1 






f,h 


21.471 


465.74 


P(2) 


lo 


e,f 


22.542 


443.61 


P(3) 


2 2 


e,f,g 


22.563 


443.20 


P(3) 


2i 


e 


22.71 


440.3 






f,g 


23.675 


422.38 


P(4) 


3 or 3i 


e,f,g 


23.86 


419.11 






f,g 


24.918 


401.32 


P(5) 


4i 


e,f,g 


25.12 


398.09 






f,g 


26.282 


380.49 


P(6) 


5 or 5i 


e,f 


30.69 


325.8 






f 


31.47 


317.7 






f 


31.951 


312.97 






f,g 


32.13 


311.2 






f,g 



a See Ref. 13. Observed in a 0.77 m long, 47.5 mm i.d. tube, pressure 0.03-0.13 Torr H 2 C:CHC1 (vinyl chloride) 

b Optically pumped by a 10 W cw C0 2 laser at 10.6114 /xm [00°1-10°0, P(22)]. 

c Optically pumped by a 10 W cw C0 2 laser at 9.5524 iim [00°l-02°0, P(20)]. 

d Proposed identifications. See Ref. 49. Identification given in form P(J)(J— 1) K . 

e See Ref. 56. Observed in a pulsed (1 pps) discharge in a 7 m long, 50 mm i.d. tube. Pressure 2.4 Torr, flow 251/min. 

f See Ref. 1. Observed in a pulsed discharge (600 amperes) in a 4.9 m long, 100 mm i.d. tube. Pressure 0.5-1 Torr. 

g Strongest transitions. 

h Observed only with wavelength selective resonator. 



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348 Handbook of Lasers 

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23. W. L. Faust and R. A. McFarlane, private communication. 

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35. A. Henry, F. Bourcin, I. Arditi, R. Charneau, and J. Menard, "Effect laser par reaction chimique de l'hydrogene sur du 
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40. R. T. Hodgson (to be published). 

41. W. Q. Jeffers and P. D. Coleman, " Spiking and time behavior of a pulsed water-vapor laser," Appl. Phys. Lett., 10, 7-9, 1967. 

42. W. Q. Jeffers and P. D. Coleman, "The far infrared stimulated emission spectrum of D 2 0," Proc. IEEE {Letters), 55, 1222- 
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43. W. Q. Jeffers, "Single wavelength operation of a pulsed water vapor laser," Appl. Phys. Lett., 11, 178-180, 1967. 

44. J. V. V. Kasper and G. C. Pimentel, "HO chemical laser," Phys. Rev. Lett., 14 (10), 352-354, 1965. 

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46. K. L. Kompa and G. C. Pimentel, "A hydrofluoric acid chemical laser," J. Chem. Phys., 47, 857-858, 1967. 

47. T. Kasuya, A. Minoh, and K. Shimoda, "A new laser emission from deuterium oxide vapor," J. Phys. Soc. Jap., 25, 1201, 
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48. T. Kasuya and D. R. Lide, Jr., "Measurements on the molecular nitrogen pulsed laser," Appl. Optics, 6, (1), 66-80, 1967. 

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51. N. Legay-Sommaire, "Interpretation and mechanism of the CS 2 -N 2 laser," Appl. Phys. Lett., 12, 34-35, 1968. 

52. L. E. S. Mathias and J. T. Parker, "Stimulated emission in the band spectrum of nitrogen," Appl. Phys. Lett., 3, 16-18, 1963. 

53. L. E. S. Mathias and J. T. Parker, "Visible laser oscillations from carbon monoxide," Phys. Lett., 7, 194-196, 1963. 

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55. L. E. S. Mathias, A. Crocker, and M. S. Wills, "Laser oscillations from nitrous oxide at wavelengths around 10.9 p," Phys. 
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56. L. E. S. Mathias, A. Crocker, and M. S. Wills, "Laser oscillations at wavelengths between 21 and 32 p. from a pulsed dis- 
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57. L. E. S. Mathias, A. Crocker, and M. S. Wills, "Laser oscillations at submillimetre wavelengths from pulsed gas discharges 
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Phys. Lett., 8, 69-70, 1966. 

61. W. M. Muller and G. T. Flesher, "Continuous wave submillimeter oscillation in H 2 0, D 2 and CH 3 CN," Appl. Phys. 
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8 Molecular Gas Lasers 349 

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74. C. K. N. Patel, " Vibrational-rotational laser action in carbon monoxide," Phys. Rev., 141, 71-83, 1966. 

75. M. A. Pollack, "Laser oscillation in chemically formed CO," Appl. Phys. Lett., 8, 237-238, 1966. 

76. M. A. Pollack, "Molecular laser action in nitric oxide by photodissociation of NOC1," Appl. Phys. Lett., 9, 94-96, 1966. 

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Dye Lasers 



Thomas F. Deutsch 

Research Division 

Raytheon Company 

Waltham, Massachusetts 02154 

TABLE 9-1. SUMMARY OF DYE LASER PROPERTIES 



Property 



Typical values 



Conditions 



Comments 



Wavelength 



Tuning 



3400-1 1,750 A 



Up to 1760 A 



Flashlamp and/or laser 
pumped 



Prism, filter, grating, 
Q-switch in cavity 



A variety of dye-solvent 
combinations are available 
to span the entire 
wavelength range nearly 
continuously 

Length, concentration, and 
temperature of active 
medium also provide tuning. 
Solvent pH affects tuning 
range. 



Spectral Width 


15-150 A 


Broadband mirrors 






~0.5 A 


Grating in cavity 






~ 0.01 A 


Grating plus etalon 




Beam Divergence 


2-5 mrad 


Flashlamp and/or laser 


Dependent on uniformity of 






pumped 


pumping 




0.5 mrad 


Etalon in cavity 




Efficiency 


Up to 25 percent 


Laser pumped 


Measured optical efficiency 




~ 0.4 percent 


Flashlamp pumped 


Electrical energy input to 
laser energy output 


/ Energy 


2J (high)- 


Flashlamp pumped 








0.1 J (typical) 








Power 


~2MW 
0.75-2.0 MW 


20 MW pump 
Flashlamp pumped 


Rhodamine 6G 




Repetition 


Up to 200 pps 


Laser pumped 


Pump laser rate limits 


Output I 


Rate 


20-50 pps 
1 pps 


Linear flashlamp 
Annular flashlamp 


System cooling and 
component failure are 
limits 






continuous 


(Laser pumped) 
Ismail cavity / 


Dye liquid flow transversely 


\ 




through cavity 


/Pulse 


~ 20 nsec 


Laser pumped 


Follows pump pulse 




Duration 












0.5|U,sec typical; 


Flashlamp pumped 


Shorter than pump duration 






up to 500 /xsec 










achieved 






Temporal < 


Mode- 




Mode-locked pump 


Pump cavity length integral 


Locked 






multiple of dye cavity 






Pulses < 10 -9 sec 


Flashlamp pumped 
with intracavity 
saturable absorber 








Pulses < 10" X1 sec 


Mode-locked pump 


Observed by two-photon 








fluorescence 



350 



9 Dye Lasers 351 
TABLE 9-2. REPORTED DYE LASERS AND WAVELENGTHS 



Organic compound 



Laser-pumped Flashlamp-pumped 
Typical solvent output wavelength, output wavelength, Reference 
angstroms angstroms 



Acridine red 

Acridone 

Acriflavin hydrochloride 

9-Aminoacridine hydrochloride 

3-Aminofluoranthene 

3-Aminophthalimide 

Aquafluor* 

BBO or 2,5-dibiphenylyloxazole 

BenzyI-/?-methylumbelliferone 

2-Biphenyl-5-styryl- 1 , 3 ,4-oxadiazole 

bis-MSB or /7-bis(o-methylstyryl)benzene 

2,5-Bis[5-terf-butylbenzoxazolyl(2)]thiophene 

Blatt griin 

Brilliant green or malachite green G 

Brilliant sulphaflavine 

Calcein blue 

6-Carboxyfluorescein 

Chloro-aluminium phthalocyanine 

Cresyl violet 

1 ,2-Di-4-biphenylethylene 

Dibromofluorescein 

2,7-Dichlorofluorescein 

4,4'-Dichloro-l,4-distyrylbenzene 

Dicyanine 

1 ,1 '-Diethyl-y-acetoxy-2,2'-dicarbocyanine 

tetrafluoroborate 
7-Diethylamino-4-methyIcoumarin 
1,1 '-Diethyl- 1 l-bromo-2,2'-quinodicarbocyanine 

iodide 
1 , 1 '-Diethyl- 1 1 -bromo-4,4'-quinodicarbocyanine 

iodide 
3,3'-Diethyl-10-chloro-2,2 , -(4,4',5,5'-dibenzo)- 

thiadicarbocyanine iodide 
3,3'-Diethyl-10-chloro-2,2'-(5,5'6,6'-dibenzo)- 

thiadicarbocyanine iodide 
1 , 1 '-Diethyl-y-cyano-2,2'-dicarbocyanine tetra- 
fluoroborate or DTCDCT 
3,3'-Diethyl-6,6',7,7'-dibenzo-ll-methylthiatri- 

carbocyanine iodide 
3,3'-Diethyl-2,2'-(4,4',5,5'-dibenzo)thiatricarbo- 

cyanine 
3,3'-Diethyl-6,6',7,7'-dibenzothiatricarbocyanine 
1 , 1 -Diethyl-2,2'-dicarbocyanine iodide 
3,3'-Diethyl-5,5'-dimethoxy-6,6'-bis(methylmer- 

capto)- 1 O-methylthiadicarbocyanine bromide 
3,3'-Diethyl-2,2'-(5,5'-dimethyl)thiazolinotri- 

carbocyanine iodide 
3,3'-Diethyl-l 1-methoxythiatricarbocyanine iodide 
1 , 1 '-Diethyl-y-nitro-4,4'-dicarbocyanine tetra- 
fluoroborate or DTNDCT 
3,3'-Diethyloxadicarbocyanine iodide 
3,3'-Diethyl-2,2'-oxatricarbocyanine iodide 
3,3'-Diethyloxytricarbocyanine iodide 
1 , 1 '-Diethyl-4,4'-quinocarbocyanine bromide 
l,l'-Diethyl-4,4'-quinocarbocyanine iodide or 

cryptocyanine 
1 ,1 '-Diethyl-2,2'-quinotricarbocyanine iodide 
1 ,1 '-Diethyl-4,4'-quinotricarbocyanine iodide 
3,3'-Diethyl-2,2'-selenatricarbocyanine iodide 
3,3'-Diethyl-2,2'-(5,5',6,6'-tetramethoxy)- 

thiatricarbocyanine 
3,3'-Diethyl-2,2'-thiadicarbocyanine iodide 



ethanol 


5800 


ethanol 


4370 


ethanol 


5100 


ethanol 




ethanol 




isoamyl alcohol 


5000 


ethanol 




benzene 


4085 


ethanol 




toluene 


3905 


ethanol 


4190 


toluene, benzene 


4250 


benzene 




sulfuric acid 


8000 


isoamyl alcohol 


7600 


ethanol 




ethanol 




ethanol 




dimethyl 


7615 


sulfoxide 




ethanol 




toluene 


4080 


glycerin 


5680 


ethanol 




toluene 


4200 


glycerin 


7560 


methanol 


7970 


ethanol 


4500 


glycerin 


8150 


methanol 


8300 


acetone 


7740 


acetone 


7140 


pyridine 


7600 


ethanol 


8560 


acetone 


8600 


ethanol 


8385 


glycerin 


7500 


ethanol 


7330 


glycerin 


7170 


ethanol 


7855 


pyridine 


8000 


methanol 


6580 


acetone 


7440 


ethanol 


7285 


glycerin 


7540 


glycerin 


7450 


acetone 


8980 


acetone 


10,000 


acetone 


8260 


acetone 


8530 



6150 


26,27 


4350 


9,26 


5175 


8,19 


4585 


10 


5480-5800 


33 




31 


4200 


9 




1,6 


4600 


10 




1 




6 


4240 


6,8 


4370 


8 




31 




18 


5080-5730 


33 


4490-4900 


33 


5390-5480 


33 




25 


6460-7090 


33 




13 




31 


-5450 


27 




13 




31 




20 


4600 


7,15,28 




14 




14 




14 




14 




3 




4 




14 




4 




29 




4 




14 




4 




3 




21 




14 




4 




14 




14,18,29 




4,14 




14 




14 




14 



acetone 



7110 



20 



352 Handbook of Lasers 

TABLE 9-2. REPORTED DYE LASERS AND WAVELENGTHS (Continued) 



Organic compound 



Laser-pumped Flashlamp-pumped 
Typical solvent output wavelength, output wavelength, Reference 
angstroms angstroms 



3,3'-Diethylthiatricarbocyanine bromide 
3,3'-Diethylthiatricarbocyanine iodide or DTTC 

2-5-Di-(/>-mefhoxyphenyi)-l,3,4-oxadiazole 

2,2'-Dimethoxy-l,4-distyrylbenzene 

1 , 1 '-Dimethyl- 1 1 -bromo-2,2'-quinodicarbocyanine 

iodide 
Dimethyl POPOP or l,4-bis-2-(4-methyl-5-phenyl- 

oxazolyl)benzene 
1 , 1 '-Dimethyl-4,4'-quinocarbocyanine iodide 
1 ,2-Di-(a-naphthyl)ethylene 
9, 1 0-Diphenylanthracene 
Diphenylbutadiene 
2,5-Diphenylfuran 
1 ,3-Diphenylisobenzofuran 
2,5-Diphenyl-l ,3,4-oxadiazole 
2-5-Diphenyloxazole 
l,4-Di[2-(5-phenyloxazolyl)]benzene 
p,/>'-Diphenylstilbene 
1 ,4-Distyrylbenzene 
Echtblau B 
Eosin 

Esculin 

7-Ethylamino-4,6-dimethylcoumarin 
3-Ethylaminopyrene-5,8, 10-trisulfonic acid 
3-Ethyl-3'-methylthiathiazolinotricarbocyanine 

iodide 
Fluorescein 

l,l',3,3,3',3'-Hexamethyl-4,4',5,5'-dibenzo- 

indotricarbocyanine perchlorate 
l,r,3,3,3',3'-Hexamethylindotricarbocyanine 

iodide 
1 , 1 ',3,3,3',3'-Hexamethyl-2,2'-indotricarbocyanine 

iodide 
7-Hydroxycoumarin or umbelliferone 

2-Hydroxy-4-methyl-7-aminoquinoline 
Isopropyl-2-phenyl-5(4-biphenylyl)-l,3,4- 

oxadiazole 
Isoquinoline red 
Lachs 
Liquifluor* 

Lissamine rhodamine B-200 
Lucegenin 



Magnesium phthalocyanine 
2'-Mefhoxy-l ,4-distyrylbenzene 
7-Methylamino-4,6-dimethylcoumarin 



Methylene blue 

Methylene green 
4-Methylum belliferone 



methanol 


8350 


ethanol 


8075 


dimethyl sulfoxide 
ethanol 


8220 
3590 




3720 


toluene 


4300 


glycerin 


7450 


cyclohexane, ethanol 4230 




4310 


glycerin 
toluene 


7490 
4260 


cyclohexane 
toluene 


4325 
3830 


dioxane 




ethanol 




dioxane, ethanol 


3470 


dioxane 




toluene 


4170 


benzene 


4085 


toluene 


4150 


glycerin 
ethanol 


7530 
5400 


ethanol 


6000 


water (pH ~ 9) 
ethanol 




water 


4410 


ethanol 


7700 


aqueous 
alkaline 


5180 


ethanol 


8245 


ethanol 


7935 


acetone 


8190 


water (pH ~ 9) 

t 


4050-5750 


ethanol 




ethanol 




water 


6200 


glycerol 
ethanol 


5400 


ethanol 




water and 


6000 


sulfuric 




acid 




quinoline 
toluene 


7590 
4250 


ethanol 




ethanol 




(weakly 

acidic) 
ethanol (acidic) 
sulfuric acid 


8290 


sulfuric acid 


8350 


sulfuric acid 


8230 


t 


3850-5740 



3710 

4840-5180 

3480 

3810 

4090 



4600 
4460 



8000 

4600 

4130 
3700 



4220 
5750-6450 



4430 
4840 



4870 



20 
4 

25 
1 

13 
14 

6,13 

14 

13 

11,15 

1 

8 

33 

1,8 

8 

13 

6,8,15 

1,13 

31 

26 

31 

28,43 

30 

21 

4 

13,15,21 

4 

4 

8,14 

32,43 

34 

30 



31 

31 

9 

33 

31 



31 
12 
30 
30 



30 
31 
31 
31 
35 



* Trademarks Pilot Chemicals, Inc., Watertown, Massachusetts. These are premixed organic scintillator solutions con- 
taining the primary scintillator PPO and the spectrum shifter POPOP. 

t Lasing range depends upon pH of solvent and resultant exciplex formation. 



9 Dye Lasers 353 
TABLE 9-2. REPORTED DYE LASERS AND WAVELENGTHS (Continued) 



Organic compound 



Laser-pumped Flashlamp-pumped 
Typical solvent output wavelength, output wavelength, Reference 
angstroms angstroms 



4-MethylumbeIliferone or 4-methyl-7-hydroxy- 

coumarin 
Monobromofluorescein 
Naphthalene green 

ocNND or 2,5-di(a-naphthyl)-l,3,4-oxadiazole 
ocNPO or 2-phenyl-5-a-naphthyl-l, 4-oxazole 
Pentacarbocyanine analogs 
Phthalocyanine 

2-Phenyl-5-(p-methoxyphenyl)-l,3,4-oxadiazole 
Pina (orthol) 
POPOP or /?-bis[2-(5-phenyloxazolyl)]benzene 

Pyronin B 



Pyronin G 
Pyronin Y 
/»-Quaterphenyl 
Rapid-filter gelt 
Rapid-filter grtin 
Rhodamine B 



Rhodamine 3B 
Rhodamine C 
Rhodamine G 
Rhodamine 6G 



Rhodamine S 

Rhoduline blue 6G 

Saphranine-T 

Sodium fluorescein 

1 -Styryl-4[a>-vinyl-(«- biphenylyl)] benzene 

p-Terphenyl 

Thionin 

Toluidine blue 

2,4,6-Triphenylpyrilium fluoroborate 

Trypaflavin 

Uranine 

Victoria blue 

Victoria blue R 

Violet rot 



water (pH ~ 9) 

ethanol 

glycerin 

glycerin 

toluene 

toluene 

nitrobenzene 

sulfuric acid 

ethanol 

ethanol 

ethanol, 
toluene 

acetone, 

polymethyl- 
methacrylate 

isoamyl alcohol 

ethanol 

DMF 

isoamyl alcohol 

glycerin 

ethanol 



4500 

5600 
7560 
3910 
3995 
10,950-11,750 
8630 
3650 
5650 
4210 

5760 



5900 



6200 
7950 
5770 



isoamyl alcohol 


6200 


glycerin 


5700 


ethanol 


5850 


ethanol 


5550 


polymethyl- 




methacrylate 




water 




(continuous 




operation 




with argon 




laser pump) 




ethanol 




glycerin 


7580 


ethanol 


6100 


water, ethanol 


5270 


toluene 


4320 


cyclohexane 


3410 


sulfuric acid 


8500 


sulfuric acid 


8480 


methanol 


4850 


ethanol 


5050 


ethanol 


5600 


glycerin 


8090 


glycerin 


8140 


isoamyl alcohol 


6200 



~4600 
4590-^640 



4000 

4190 
yellow 



6000 

5900-6350 

3740 



6200 



6150 
6200 

5950 



15,27,28 

33 

31 

31 

1 

6 

17 

31 

1 

31 

6,9,15 

10,13,22 



18,31 

33 

8 

31 

31 

2,5,16,19, 
21,22, 
23,26, 
27,31, 
32,43 

18,31 

13,18 

10,19 

22,23,27 

8,13,15,16, 
18,19, 
24,26, 
31 

36 



5860 


10 




31 




13 


5450 


26,27 




13 


3410 


1,8 




31 




31 




21 




31 




25,31 




31 




31 




31 



354 Handbook of Lasers 

A note on the preparation of dye solutions 

A number of workers have noted the role of various additives to the dye solution. Molecular 
oxygen quenches the lifetime of the triplet state and usually increases the duration of lasing, 37 but 
since it can also enhance singlet-triplet transitions, in some cases it decreases the laser output. The 
effect of oxygen addition has been studied for a number of dyes. 38 Cyclooctatetraene has been used to 
quench the triplet state of rhodamine 6G. 39 Detergents have been used to prevent dimerization of 
rhodamine 6G in aqueous solution 40 and in gels. 41 Selecting the pH of the solution can determine the 
tuning range of those dyes where exciplex formation occurs. 42 



REFERENCES 

1. G. A. Abakumov, A. P. Simonov, V. V. Fadeev, M. A. Kasymdganov, L. A. Kharitonov, R. V. Khokhlov, Opto-Electronics, 
1, 205, 1969. 

2. M. Bass, T. F. Deutsch, and M. J. Weber, Appl. Phys. Lett., 13, 120, 1968. 

3. D. J. Bradley, A. J. F. Durrant, G. M. Gale, M. Moore, and P. D. Smith, IEEE J. Quant. Electr., QE-4, 707, 1968. 

4. L. D. Derkacheva, A. I. Krymova, A. F. Vompe, and I. I. Levkoev, Opt. Spectry. (USSR), 25, 404, 1968. 

5. T. F. Deutsch, M. Bass, P. Meyer, and S. Protopapa, Appl. Phys. Lett., 11, 379, 1967. 

6. T. F. Deutsch and M. Bass, IEEE J. Quant. Electr., QE-5, 260, 1969. 

7. C. M. Ferrar, IEEE J. Quant. Electr., QE-5, 550, 1969. 

8. H. W. Furumoto and H. L. Ceccon, /. Quant Electr., QE-6, 262, 1970. 

9. H. Furumoto and H. Ceccon, J. Appl. Phys., 40, 4204, 1969. 

10. D. W. Gregg and S. J. Thomas, IEEE J. Quant. Electr., QE-5, 302, 1969. 

11. B. G. Huth and G. I. Farmer, IEEE J. Quant. Electr., QE-4, 427, 1968. 

12. V. D. Kotzubanov, L. Ya. Malkes, Yu. V. Naboikin, L. A. Ogurtsova, A. P. Podgornyi, and F. S. Pokrovskaya, Bull. Acad. 
Sci. (USSR), 32, 1357, 1968. 

13. V. D. Kotzubanov, Yu. V. Naboikin, L. A. Ogurtsova, A. P. Podgornyi, and F. S. Pokrovskaya, Opt. Spectry. (USSR), 
25, 406, 1968. 

14. Y. Miyazoe and M. Maeda, Appl. Phys. Lett., 12, 206 1969. 

15. J. A. Myer, C. L. Johnson, E. Kierstead, R. D. Sharma, and I. Itzkan, Appl. Phys. Lett., 16, 3, 1970. 

16. O. G. Peterson and B. B. Snavely, Appl. Phys. Lett., 12, 238 1968. 

17. O. G. Peterson and B. B. Snavely, Bull. Am. Phys. Soc, 13, 397, 1968. 

18. A. N. Rubinov and V. A. Mostovnikov, Bull. Acad. Sci. (USSR), 32, 1348, 1968. 

19. H. Samelson, Electronics, 41, (23), 142, 1968. 

20. F. P. Schafer, W. Schmidt, and J. Volze, Appl. Phys. Lett., 9, 306, 1966. 

21. F. P. Schafer, W. Schmidt, and K. Marth, Phys. Lett., 24A, 280, 1967. 

22. W. Schmidt and F. P. Schafer, Z. Naturforsch., 22a, 1563, 1967. 

23. B. B. Snavely and O. G. Peterson, IEEE J. Quant. Electr., QE-4, 540, 1968. 

24. B. B. Snavely and F. P. Schafer, Phys. Lett., 28A, 728, 1969. 

25. P. P. Sorokin, J. R. Lankard, E. C. Hammond, and V. L. Moruzzi, IBM J. Res. Develop., 11, 130, 1967. 

26. P. P. Sorokin and J. R. Lankard, IBM J. Res. Develop., 11, 148, 1967. 

27. P. P. Sorokin, J. R. Lankard, V. L. Moruzzi, and E. C. Hammond, /. Chem. Phys., 48, 4726, 1968. 

28. P. Sorokin, Sci. Am. 220, (2), 30, 1969. 

29. M. L. Spaeth and D. P. Bortfeld, Appl. Phys. Lett., 9, 179, 1966. 

30. R. Srinivasan, IEEE J. Quant. Electr., QE-5, 552, 1969. 

31. B. I. Stepanov and A. N. Rubinov, Sov. Phys. Uspekhi, 11, 304, 1968. 

32. M. J. Weber and M. Bass, IEEE J. Quant. Electr., QE-5, 175, 1969. 

33. J. B. Marling, D. W. Gregg, and S. J. Thomas, IEEE J. Quant. Electr., QE-6, 570, 1970. 

34. A. Dienes, C. V. Shank, and A. M. Trozzolo, Appl. Phys. Lett., 17, (5), 189, 1970. 

35. C. V. Shank, A. Dienes, A. M. Trozzolo, and J. A. Myer, Appl. Phys. Lett., 16, (10), 405, 1970. 

36. O. G. Peterson, S. A. Tuccio, and B. B. Snavely, Appl. Phys. Lett. 17, 245, 1970. 

37. B. B. Snavely and F. P. Schafer, Phys. Lett., 28A, 728, 1969. 

38. J. B. Marling, D. W. Gregg, and S. J. Thomas, IEEE J. Quant. Elect., QE-6, 570, 1970. 

39. R. Pappalardo, H. Samelson, A. Lempicki, Appl. Phys. Lett., 16, 267, 1970. 

40. O. G. Peterson, S. A. Tuccio, and B. B. Snavely, Appl. Phys. Lett., 17, 245, 1970. 

41. T. W. Hansch, M. Pernier, A. L. Schawlow, IEEE J. Quant. Elect., QE-7, 45, 1971. 

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Rare Earth Liquid Lasers 

Alexander Lempicki 

GTE Laboratories, Inc. 
Bay side, New York 11361 

Lasers listed in this chapter use rare earth ions in solution. All of these lasers have been operated 
only in a pulsed mode, using xenon-filled flashlamps for optical excitation. 

CHELATE LASERS 

The chelates are a class of laser materials in which the active ion is a trivalent rare earth (RE) 
bonded to several organic groups or ligands. Most chelates, are soluble in a number of organic solvents, 
and are historically important because a Eu-chelate dissolved in alcohol was the first liquid material 
to exhibit laser action. 6 

Two general types of compounds can be distinguished : 

(RE) + 3 [ligand] _ 4 Q + Tetrakis chelates 
(RE) + 3 [ligand] _ 3 Tris chelates 

where Q + is a cation. 

Table 10-1 gives a partial list of ligands, cations and the most commonly used solvents. In all rare 
earth chelate lasers, emission is determined by ionic levels of the metal ion, and pump bands are deter- 
mined by absorption bands of the ligands (Figure 10-1). The most extensively studied ion is Eu +3 . Typical 



CHELATE STATES 



32000 
30000 
28000 



W77TT/, 
SINGLET/, 
_ ABSORPTION 

''MIM 




ENERGY TRANSFER SCHEME 



Fig. 10-1 . Energy levels of a typical Eu-chelate molecule. Pumping transition from ground state to high lying singlet 
states characteristic of ligand, followed by intersystem crossing to triplet state and intermolecular transfer to excited 
states of the rare earth ion. Fluorescent (laser) emission between ionic states ( 5 D — 7 F 2 ). 



355 



356 



Handbook of Lasers 



chelate laser materials are listed in Table 10-2. The efficiency of chelate lasers is limited by excessive 
absorption in pump band regions; output energy is limited by the very small volume of active material 
that can be effectively pumped. Extensive search for different [ligand] and Q combinations has not 
yielded materials of significantly higher efficiency. Small changes in wavelength (for a particular ion) 
can be achieved by changing the ligand or the cation. 1417 

TABLE 10-1. LIGANDS, CATIONS AND SOLVENTS USED IN 
RARE EARTH CHELATE LASERS (PARTIAL LISTING) 



LIGANDS 




Trifluoroacetylacetone 


O O 

II II 

CF 3 -C-CH 2 -C-CH 3 


TFA 




Benzoylacetone 


O O 

II II 

C 6 H 5 — C-CH 2 -C-CH 3 


B 




Benzoyltrifluoroacetone 


O O 

II II 

CF 3 -C-CH 2 -C-C 6 H 5 


BTF 




Di benzoylmethane 


O O 

II II 

C 6 H 5 -C-CH 2 -C-C 6 H 5 


DBM 




Thenoyltrifluoroacetone 


O O 
II II 
C 4 H 3 -S-C-CH 2 -C-CF 3 


TTF 




I Pentafluoropropionate 
(o-Phenanthroline 


CF 3 CF 2 COO 

C 12 H 8 N 2 


PFP,o-Ph 


CATIONS 


Piperidinium 

Pyridinium 

Sodium 

Ammonium and derivatives 

Imidazolium 


SOLVENTS 




Mixed alcohol 
DMFA 
Acetonitrile 
Dimethyl sulfoxide 


Composition 

Ethanol-methanol (3:1) 
Alcohol-dimethylformamide 





10 Rare Earth Liquid Lasers 
TABLE 10-2. RARE EARTH CHELATE LASER MATERIALS 



357 



Ion 

Ligand 

Solvent 


Eu +3 

B 4 

Mixed alcohol 

or 

DMFA 


Eu +3 
[DBMU 
DMFA 
(9:3:2) 


Eu +3 

[TTF] 4 

Acetonitrile 


Eu +3 

[BTF] 4 

Acetonitrile 


Tb +3 
tTFA] 3 
p-Dioxanc; 
acetonitrile 


Nd +3 
PFP,o-Ph 
Dimethyl 
sulfoxide 


Ion concentration 


(6:2:1) 
1 x 10 18 


9x 10 18 


3 x 10 18 


6x 10 18 


1.5 x 10 18 


1.2 x 10 20 


(cm" 3 ) 

Emission 

wavelength 
Operating temp. 


to 

15 x 10 18 
6111 to 

6131A 
- 150 to 

- 130°C 


6120A 
- 145°C 


6125A 
-35°C 


6119A 
+ 30°C 


5470A 
+ 30°C 


10,570A 
-30°C 


Fluorescence 


0.8 ms 


— 


— 


0.8 ms 


— 


0.005 ms 


lifetime 
Spontaneous 

linewidth 
Laser transition 
Ground state 


20 cm" 1 

5 D - 7 F 2 
~ 900 cm" 1 


6 cm -1 

5 D - 7 F 2 
~ 900 cm" 1 


25 cm- 1 

5 D - 7 F 2 
~ 900 cm" 1 


34 cm -1 

5 D - 7 F 2 
~ 900 cm" 1 


5 D 4 - 7 F 5 


~ 140 cm -1 

r 3/2 — All/2 

~ 2000 cm -1 


splitting 
Pump bands 


2800 to 
3800A 








— 


Nd bands 


Peak absorbance in 


6.8 x 10* 


10M0 5 


10*-10 5 


10 4 -10 5 




— 


pump bands 
(liters mole -1 
cm" 1 ) 
Approx. threshold 


300 J 


1500 J 


800 J 


1500 J 


1500 J 


300 J 


Energy output 
References 


io- 3 J 

6,7,11 


8 


9,15 


10~ 2 J 
10,13 


16 


12 



SELECTED REFERENCES 



General and Laser Performance 

1. S. I. Weissman, /. Chem. Phys., 10, 214, 1942. 

2. R. E. Whan, G. A. Crosby,/. Mol. Spectr., 8, 315, 1962. 

3. G. A. Crosby, R. E. Whan, Naturwiss. 47, 276, 1960. /. Chem. Phys., 32, 614, 1960. 

4. G. A. Crosby, R. E. Whan, R. M. Alire, /. Chem. Phys., 34, 743, 1961. 

5. E. J. Schimitschek, E. G. K. Schwartz, Nature, 196, 832, 1962. 

6. A. Lempicki, H. Samelson, Phys. Lett., 4, 133, 1963. 

7. A. Lempicki, H. Samelson, C. Brecher, J. Chem. Phys., 41, 1214, 1964. 

8. E. J. Schimitschek, R. B. Nerich, J. Appl. Phys., 35, 2786, 1964. 

9. E. J. Schimitschek, R. B. Nerich, J. A. Trias, J. Chem. Phys., 42, 788, 1965. 

10. H. Samelson, A. Lempicki, C. Brecher, V. Brophy, Appl. Phys. Lett., 5, 113, 1964. 

11. Y. Mayer, R. Astier, J. Simon, C. R. Acad. Sci. Paris, 259, 4604, 1964. 

12. A. Heller,/. Am. Chem. Soc, 89, 167, 1967. 

13. E. J. Schimitschek, J. A. Trias, R. B. Nerich, /. Appl. Phys., 36, 867, 1965. 

14. H. Samelson, V. A. Brophy, C. Brecher, A. Lempicki,/. Chem. Phys., 41, 3998, 1964. 

15. Tris form also used in plastic (polymethyl methacrylate) matrix. 
N. E. Wolff and R. J. Pressley, Appl. Phys. Lett., 2, 152, 1963. 

16. S. Bjorklund, G. Kellermeyer, C. R. Hurt, N. Filipescu, Appl. Phys. Lett., 10, 160, 1967. 
Review 

17. E. J. Schimitschek, R. B. Nerich, J. A. Trias, /. Chim. Phys., 64, 173, 1967. 

18. D. L. Ross, J. Blanc, Advances in Chem. Ser. No. 71, 155, 1967. 

19. A. Lempicki, H. Samelson, C. Brecher, Appl. Opt. Supl. 2, Chem. Lasers, 205, 1965. 

20. A. Lempicki, H. Samelson, "Lasers," Vol. 1, Ed. A. K. Levine; M. Dekker Inc. Publ. N.Y. 1966. 

21. H. Samelson, C. Brecher, A. Lempicki, /. Chim. Phys., 64, 165, 1967. 

22. L. D. Derkacheva, G. V. Peregudov, A. I. Sokolowskaya, Sov. Phys. Uspekhi, 10,91, 1967. 



358 



Handbook of Lasers 



APROTIC LASERS 

Aprotic liquid laser materials consist of a solution of a rare earth salt in an inorganic aprotic 
solvent. So far only Nd +3 in selenium or phosphorous oxychlorides has been used. A summary of laser 
characteristics is given in Table 10-3. A typical absorption spectrum is shown in Figure 10-2, and 
intensities of the main pump bands are given in Table 10-4. 




3000 4000 5000 



6000 7000 8000 9000 

o 



WAVELENGTH (A) 

Fig. 10-2. Typical absorption spectra of Nd +3 in aprotic solvents. 5 
COMMON PROPERTIES OF Nd +3 APROTIC LASERS:* 



Temperature of operation 

Nd +3 concentration commonly used 

Laser transition 

Spontaneous line width 

Ground state splitting 

Threshold energy 



+ 30°C 

0.5 x 10 20 -3 x 10 20 cm" 3 

4 F - 4 T 

r 3/2 Ml/2 

~ 120 cm" 1 
~ 2000 cm -1 
< 10 joules 



Ion 



Nd +3 

Nd +3 
Nd +3 



TABLE 10-3. APROTIC LASER MATERIALS 



Solvent^ 



SeOCl 2 :SnCl 4 (0.5M) 

POCl 3 :SnCl 4 (1.0M) 
POCl 3 :ZrCl 4 (0.45M) 



Emission 
wavelength 

(A) 



10,550 
13,300 
10,510 
10,510 



Fluoresc. 

lifetime 

(ms) 



0.280 

0.300 
0.330 



Emission 

cross-section 

(cm 2 ) 



Reported 
energy 
output 
(Joules) 



References 



8 x 10- 20 
7x 10~ 21 
6x 10" 20 
6x 10- 20 



50 1,2,3,4,8 

— 11 

300 5,6,7,10 

40 9 



f Composition of solvent to be understood as follows: one liter of oxychloride plus (X Moles) of tetrachloride. 

* Except for a single reported experiment, 11 where laser action in Nd:SeOCl 2 : SnCl 4 was obtained at 13,300 A 
( 4 F3 / 2 - 4 I 13/2 transition) . 



10 Rare Earth Liquid Lasers 359 



TABLE 10-4. PEAK ABSORBANCE OF Nd +3 
PUMP BANDS IN APROTIC SOLVENTS 





Peak absorbance {liters mole 1 cm *) 


Nd +3 Pump band 










peak wavelength 


/nSeOCl 2 :SnCl 4 


wiPOCl 3 :SnCl 4 


(A) 




orPOCl 3 :ZrCU 


3500 




11.7 


5200 


11.7 


6.7 


5800 


33.3 


2.0 


7500 


16.7 


16.7 


8000 


26.7 


26.7 


8700 


10.0 


5.0 



SELECTED REFERENCES 

General and Laser Performance 

1. A. Heller, Appl. Phys. Lett., 9, 106, 1966. 

2. A. Lempicki, A. Heller, Appl. Phys. Lett., 9, 108, 1966. 

3. A. Heller, /. Am. Chem. Soc., 90, 3711, 1968. 

4. A. Heller, /. Mol. Spec, 38, 102, 1968. 

5. C. Brecher, K. French,/. Phys. Chem., 73, 1785, 1969. 

6. N. Blumenthal, C. B. Ellis, D. Grafstein, /. Chem. Phys., 48, 5726, 1968. 

7. A. Lempicki, H. Samelson, Proc. N. Y. Acad. Sci., 168, 596, 1970. 

8. H. Samelson, A. Heller, C. Brecher, J. Opt. Soc. Am., 58, 1054, 1968. 

9. E. Schimitschek, J. Appl. Phys., 39, 6120, 1968. 

10. P. M. Buzhinskii et al., Dokl. Akad. Nauk SSSR, 185, 1306, 1969. 

11. A. Heller. V. Brophy, /. Appl. Phys., 39, 4086, 1968. 
Review 

A. Heller, Phys. Today, 20, 34, 1967. 

A. Lempicki, H. Samelson, Sc. American, 216, 81, 1967. 



Commercial Laser Glasses 

Richard F. Woodcock 

American Optical Corporation 

Central Research Laboratory 

Southbridge, Massachusetts 01550 

The data presented here are restricted to those glasses that are commercially available. More 
detailed discussions of laser glass properties, including data on experimental glasses, are available in 
the literature. 1-5 

Data on laser threshold, slope efficiency, and output performance were not included in the tabu- 
lated data, because these parameters depend so strongly on cavity design. The following examples 
illustrate the extremes in performance that have been achieved with glass laser systems. Thresholds for 
laser action as low as 0.9 joules have been obtained 6 for clad laser rods 3.0 cm long with a 0.1 mm 
diameter core. Slope efficiencies up to 9 % have been reported in the literature 7 for rods 20 mm in 
diameter by 92.4 cm long, and efficiencies of 12 % have been predicted. 3 In the millisecond time domain, 
output energies as high as 5000 joules in a 10 milliradian beam angle have been obtained from a clad 
glass laser rod 1 meter long with a 30 mm active core diameter. 8 In the picosecond time domain, 51 
joule pulses with power densities of 17 x 10 12 watts have been reported. 9 Diffraction limited, lowest 
order mode glass laser systems have produced high radiance outputs of 2 x 10 17 watts/cm 2 steradian 10 
from an oscillator-amplifier system in which the output from the last amplifier rod (38 mm diameter 
by 1 meter long) was 90 joules in a 40 microradian beam angle. 

Damage in laser glass is currently receiving much attention and has been the subject of two 
symposia, June 1969 11 and June 1970, 12 sponsored by the American Society for Testing and Materials, 
and a study by the National Materials Advisory Board of the National Academy of Sciences and the 
National Academy of Engineering. In a report by the latter, 13 it is concluded that the three main 
causes of laser damage in glass laser material are : 

(1) Absorption of light by metallic and nonmetallic inclusions followed by thermally induced 
fracture around the inclusion. 

(2) Intrinsic bulk damage initiated by a self-focusing mechanism resulting in plasma formation 
and filamentary damage tracks. 

(3) Surface damage accompanied by plasma formation at the surface. 

At the time at which the above report was issued, it was felt that inclusions were the most serious 
cause of damage, but that glass with a low absorption loss and a damage threshold of 20 joules/cm 2 
in a 3 x 10" 8 second pulse was being produced with a reasonable yield in both platinum and ceramic 
crucibles. 

The threshold for intrinsic damage in bulk glass is over 1000 joules/cm 2 in a 3 x 10" 8 second 
pulse. These intensities can be reached by a self-focusing mechanism, which has a threshold of formation 
in the range of 50 to 100 joules/cm 2 for a 3 x 10" 8 second pulse. 

The mechanism for surface damage is only partially understood. Surface preparation appears to 
play the major role in determining the threshold for surface damage. 14 By appropriate surface treat- 
ment, surface damage thresholds of 100 joules/cm 2 should be possible 13-15 in a 3 x 10" 8 second pulse. 

The threshold for laser damage appears to vary with the duration of the laser pulse. The threshold 
for inclusion-induced damage varies, in a complex manner, with both pulse duration and particle 
size. 13 The threshold for surface damage appears to decrease with decreasing pulse duration. 15,16 Self 
focusing not only depends on the pulse duration, but also on beam uniformity and the length of the 
sample being tested. 1516 A good review of self-focusing is given in Reference 17. 

Typical absorption spectra of various types of laser glass are shown in Figure 11-1. 

360 



11 Commercial Laser Glasses 361 



100 




300 



100 



300 



100 



300 



400 



500 600 700 800 900 1000 1100 1200 

WAVELENGTH (nm) 




' Y ~^\J~) 



I Nd-Yb LASER GLASS 




note scale change 



400 



500 600 800 1000 1200 1400 1600 
WAVELENGTH (nm) 




400 



500 600 800 1000 1200 1400 1600 
WAVELENGTH (nm) 



Fig. 11-1. Typical absorption spectra of neodymium, neodymium-ytterbium and erbium laser glasses. 



362 Handbook of Lasers 

TABLE 11a. PROPERTIES OF COMMERCIAL LASER GLASSES 



GENERAL DATA 




Units 


















Glass designation 




NS-2024" 


NS-1838" 


NS-1020 a 


NS-0835" 


ED-2 6 


LG52 C 


LG54 C 


LG55 C 


Active ion 




Nd 3 + 


Nd 3 + 


Nd 3 + 


Nd 3 + 


Nd 3 + 


Nd 3 + 


Nd 3 + 


Nd 3 + 


Concentration : 




















J by oxide 

I by ion x 10 2 ° 


wt% 


1.0 


2.0 


3.0 


5.0 


3.1 


2 


2 


5 


ions/cm 3 


0.9 


1.8 


2.8 


4.6 


2.83 








Sensitizer element(s) 




















LASER PROPERTIES 


Fluorescent lifetime 


ms 


.640 


.630 


.620 


.570 


.300 


.150 


.080 


.600 


Laser wavelength 


jum 


1.060 


1.060 


1.060 


1.060 


1.0623 








Fluorescent line width 


nm 








26 


26 


36 


37 


22 


Loss coefficient 6 


%/cm 










0.5 








Gain coefficient 


%/cm/joule 
stored/cm 3 








0.08 e 


0.1 6 f 








OPTICAL PROPERTIES 


Refractive index: 




















#589. 3 




1.5109 


1.5135 


1.5143 


1.5196 




1.6769 


1.6943 


1.5226 


W 1.060 




1.5010 


1.5034 


1.5045 


1.5093 


1.5559 






1.5117 


#1.54 




















Abbe value 










58.6 


51.5 








Brewster's angle 










56° 30' 


57° 16' 








(at laser wavelength) 




















Absorption coefficient 


%/cm 


0.2 


0.2 


0.2 


0.2 




0.51 


0.51 


0.73 


(at laser wavelength) 




















Stress optical coef. : 




















IV 


(Brewsters 








3.63 










B„» 


or 








0.90 










B A ' 


lx 10~ 7 /bar 








-2.73 










An/nAT 


x 10- 6 /°C 








-2.2 








-2.1 


(at laser wavelength) 




















OTHER PHYSICAL PROPERTIES 


Density 


g/cm 3 


2.54 


2.56 


2.59 


2.63 


2.547 


3.77 


4.34 


2.62 


Young's modulus 


x 10 6 psi 








9.91 


13.07 


12.5 


12.0 


8.98 


Shear modulus 


x 10 6 psi 










5.2 








Poisson's ratio 










.225 


.242 








"~ a Glass manufactured by: 


















° American Optical. 




e Schott. 














" Owens-Illinois. 




d Sovirel. 















e Active measurement. 

f Passive measurement. 

9 £ ± = AnJP y ; change in index for light polarized in a direction normal to the stress (cf. "Properties of Glass " Morev Reinhold o 427 

New York, 1938). ' F " 

* B \\ = An y IP y ; change in index for light polarized in a direction parallel to the stress. 
1 2? A = 2*|| — B ± ; relative stress optical coefficient or stress birefringence coefficient. 



11 Commercial Laser Glasses 363 
TABLE 11a. PROPERTIES OF COMMERCIAL LASER GLASSES (Continued) 







Units 


NS-2024 


NS-1838 


NS-1020 


NS-0835 


ED-2 


LG 52 


LG 54 


LG 55 


Thermal conductivity 




W/m'C 












.8 


.6 


.93 


jatO'C 












.80 


1.21 








iat 100'C 












.91 


1.35 








Specific heat 




cal/gfC 








.140 










Coefficient of thermal 




x 10" 6 /'C 


10.8 


10.20 


11.11 


10.3 


10.3 


7.2 


8.6 


9.1 


expansion 






















Strain point (tj >* 10 14 


5 ) 


c 


416 


419 


424 


428 


435 






10.65 


Anneal point (•>? = 10 ,3 °) 


°c 


453 


457 


463 


467 


465 


624 


611 


480 


Softening pt. (77 ■ 10 7 


6 ) 


°c 


648 


651 


659 


661 


590 


742 


697 


667 


Hardness: 






















Knoop 




kg/mm 2 


432 


441 


468 


490 


543.6 


671 


677 


450 


Vickers 




kg/mm z 



















TABLE lib. PROPERTIES OF COMMERCIAL LASER GLASSES 



GENERAL DATA 


















Glass designation 
Active ion 


Units 


LG 56 c 

Nd 3+ 


LG 57 c 
Nd 3 + 


LG 630 c 

Nd 3 + 


915 d 

Nd 3 + 


NY 2143" 
Yb 3 + 


NY I486" 

Yb 3 + 


NYE 2101/2400" 
Er 3 + 


Concentration: 


















(by oxide 
(by ion x lO 20 
Sensitizer element(s) 


Wt % 
ions/cm 3 


3 


0.8 


3.0 


3.0 


3 
Nd 


4 
Nd 


0.3 
Nd, Yb 


LASER PROPERTIES 
















I 


Fluorescent lifetime 


ms 


.650 


.600 


.640 


.700 


2.4 


2.3 


14.0 


Laser wavelength 
Fluorescent line width 


/xm 

nm 


22 


21 


22 




1.06 


1.06 


1.54 


Loss coefficienf 


%/cm 








.07 






1 


Gain coefficient 


%/cm/joule 
stored/cm 3 








.07 








OPTICAL PROPERTIES 
















Refractive index : 

"589.3 




1.5199 


1,5171 


1.5199 


(1.517) 


1.5198 


1.527 


1.5332 


"1.06O 

«1.54 




1.5093 


1 .5065 


1.5091 


1,5067 


1.5075 


1.515 


1.5226 
(1.5191) 


Abbe value 










58.1 








Brewster's angle 

(at laser wavelength) 
Absorption coefficient 


%/cm 


0.51 


56 26' 

.73 


56- 28' 
.1-.2 


.23 








(at laser wavelength) 


















a-d Glass manufactured by: 

" American Optical. 
* Owens-Illinois. 

e Active measurement- 

' Passive measurement. 




c Schott. 
"Sovirefc 













364 Handbook of Lasers 
TABLE lib. PROPERTIES OF COMMERCIAL LASER GLASSES (Continued) 



Units LG56 LG 57 LG 630 915 NY 2143 NY 1486 NYE 2101/2400 



Stress optical coef . : 

B ± a /•Brewsters 
B„ 6 or 

B A C Ul0- 7 /bar 

An/nAT x 10" 6 / o C -2.4 -2.1 -2.2 

(at laser wavelength) 



OTHER PHYSICAL PROPERTIES 


Density 


g/cm 3 


2.69 


2.59 


2.59 


2.60 


2.62 


2.7 




Young's modulus 


x 10 6 psi 


8.78 


9.13 


8.78 


9.37 








Shear modulus 


x 10 6 psi 
















Poisson's ratio 


















Thermal conductivity 


W/m°C 


.93 


1.16 


.99 


~.84 








|atO°C 


















lat 100°C 


















Specific heat 


cal/g/°C 








~.2 








Coefficient of 


x 10- 6 /°C 


9.3 


9.58 


9.7 


9.61 


10.4 


10.0 


9.4 


thermal expansion 


















Strain point (77 = 10 14 - 5 ) 


°c 


10.65 








433 


466 


513 


Anneal point (77 = 10 130 ) 


°c 


468 


453 


465 




473 


498 


556 


Softening pt. (17 = 10 7 - 6 ) 


°c 


665 


640 


665 




674 


703 


761 


Hardness : 


















Knoop 


kg/mm 2 


475 


391 


365 


404 








Vickers 


kg/mm 2 




473 


475 











" B ± = AnJP y ; change in index for light polarized in a direction normal to the stress (cf. " Properties of Glass," Morey, Reinhold, p. 427 

New York, 1938). 
b B\\ =An y /P y ; change in index for light polarized in a direction parallel to the stress. 
c BA = B n — 2? x ; relative stress optical coefficient or stress birefringence coefficient. 



REFERENCES 

1. Patek, K., "Glass Lasers." Ed. J. G. Edwards, CRC Press, Cleveland, 1970. 

2. Snitzer, E., "Glass Lasers," Appl. Optics, 5 (10), 1487, 1966. 

3. Young, C. G., "Report on Glass Lasers," Microwaves, 7, 69-78, July 1968. 

4. Snitzer, E., "Glass Lasers," Glass Ind., 48, 11-19, Sept./Oct. 1967: 48 (9), 498, 555, 1967. 

5. Snitzer, E. and Young, C. G., "Glass Lasers," in "Advances in Lasers," vol. 2, Ed. A. Levine, Dekker, New York, 1968. 

6. Young, C. G., "Continuous Glass Laser," Appl. Phys. Lett., 2 (8), 151, 1963. 

7. Beck, R. W., "Predicted Output of Glass Laser Materials," Laser Focus, 5 (11), 42, 1969. 

8. Young, C. G., "Glass Laser Delivers 5000- Joule Output," Laser Focus, 3 (3), 36, 1967. 

9. Gobeli, G., "Powerful Pulsed Laser Bows," Electronic News, 14, 72, 1969. 

10. Hagen, W. F., "Diffraction Limited High Radiance Nd-Glass Laser System," /. Appl. Phys., 40 (2), 511, 1969. 

11. "Damage in Laser Glass," ASTM Special Technical Publication 469, ASTM, Philadelphia, 1970. 

12. To be published. 

13. "Fundamentals of Damage in Laser Glass," Publication NMAB-271, National Academy of Science-National Academy of 
Engineering, Washington, 1970. 

14. Swain, J. E., "Surface Damage Measurements for Several Glasses," ASTM STP 469, ASTM, Philadelphia, 69, 1970. 

15. Davit, J., "Laser Damage in Optical Glasses," ibid. 100. 

16. Young, C. G. and Woodcock, R. F., "Laser-Induced Damage in Glass," ibid. 84. 

17. Akhmanov, S. A., Sukhorukov, A. P., and Khoklov, R. V., " Self Focusing and Diffraction of Light in a Nonlinear Medium," 
Sov. Phys. Uspekhi, 93, 609, 1968. 



Injection Lasers 

Jacques I. Pankove 

RCA Laboratories 
Princeton, New Jersey 08540 



USEFUL FORMULAE FOR SEMICONDUCTOR LASERS 

Threshold condition: 1 



1 , l 
,.« + z ln- 



Ah 


-;« 


1 
R 


a 


/* = 


Snqn 2 


v 2 


AvJ 


c 2 


fsp 



where g = gain per unit length 
a = losses per unit length 
L = length of Fabry-Perot cavity 
R = reflectance of Fabry-Perot facets 

Threshold current density for injection lasers: 



where fi is the gain coefficient 



here d = thickness of active region 

q = electron charge 

n = refractive index 

v = frequency of radiation 
Av = emission line width 

c = velocity of light in vacuum 
*7s P == quantum efficiency for spontaneous emission 

Note relationship between gain g and gain coefficient /?: 

9 = & 
where j = current density. 

Typical performance of GaAs injection lasers: 





pn junction 


Close confinement structure 




single heterojunction 2 


double heterojunction* 


Temperature 
a (cm -1 ) 
]8 (cm/A) 
/,„ (A/cm 2 ) 


77°K 300°K 
13 100 
2xl0~ 3 2-3 xlO" 3 
10 3 4xl0 4 


77°K 300°K 
10 20 
4xl0~ 2 3-6 xlO" 3 
8xl0 2 8 xlO 3 


77°K 300°K 
7 15 
l.OxlO" 1 1.5X10" 2 
1.5 xlO 2 1.3 XlO 3 



365 



366 Handbook of Lasers 

Temperature dependence of threshold current density: 4 

J th = J exp {TI6) 

Typical values: J = 100 - 500 A/cm 2 
0= 50- 110°K 

Steady-state temperature rise of injection laser: 

AT=Q[IVj(l -rj) + I 2 r] 

where Q = thermal resistance (typically 30°/W for GaAs) 
I = current through the diode 
Vj = junction voltage (&hv) 
r\ = external quantum efficiency 
r = internal resistance 

Power efficiency: 



where P = output power 

V — voltage across laser diode 

Differential power efficiency: 



Differential quantum efficiency: 



IV 



*Jd P = 



V-J^v 



or 



rj = 



r\ = 



(I-IJhv 

lnl/i? 
ocL + In l/R 



fit 



where / = current through junction 
I ih = threshold current 
hv = photon energy 
rjt = internal quantum efficiency 
Note that at low currents V « hv and r\ « rj dp 
at larger currents V ' « hv + Ir 

r = diode internal resistance 



Mode structure: 



M = 



2nL 



where M = number of modes in cavity 
n = index of refraction 
L = cavity length 
X = wavelength in vacuum 
Separation between wavelengths of adjacent modes : 

J 2 



r i dn ~\ 



2L 



12 Injection Lasers 367 

Radiation pattern: 

§ = arc sin (0.886 Xjd) general case 

<f) = 0.886 kjd small angle approximation 

4> — half width of laser beam (from maximum intensity to half maximum intensity) 

d = thickness of active region measured at the exit facet 



REFERENCES 

1. G. Lasher, IBM J. Res. & Dev., 7, 58, 1963. 

2. H. Kressel, H. Nelson, and F. Z. Hawrylo, /. Appl. Phys., 41, 2019, 1970. 

3. Jh. I. Alferov, V. M. Andreev, V. I. Korolkov, E. L. Portnoi, and D. N. Tretyakov, Sov. Phys. — Semiconductors, 2, 1289-1291, 
April, 1969. 

Jh. I. Alferov, V. M. Andreev, E. L. Portnoi, and M. K. Trukan, Sov. Phys. — Semiconductors, 3, 1107, 1970. 
M. B. Panish, I. Hayashi, and S. Sumski, Appl. Phys. Lett., 16, 326, 1970. 
H. Kressel and F. Z. Hawrylo, Appl. Phys. Lett., 17, 169, 1970. 

4. J. I. Pankove, IEEE J. Quant. Electronics, 4, 119, 1968. 

5. J. R. Biard, W. N. Carr, and B. S. Reed, Trans. AIME, 230, 286, 1964. 

MAJOR REVIEW LITERATURE ON SEMICONDUCTOR LASERS 
IN CHRONOLOGICAL ORDER 

G. Burns and M. I. Nathan, Proc. IEEE, 52, 770, 1964. 

M. I. Nathan, Proc. IEEE, 54, 1276, 1966. 

F. Stern, Semiconductor and Semimetals 2, 1, 1966, Academic Press. 

P. T. Landsberg, Solid State Electronics, 10, 513, 1967. 

M. H. Pilkuhn, Phys. Stat. Solidi, 25, 9, 1968. 

"Gallium Arsenide Lasers," ed. C. H. Gooch; Wiley-Interscience, 1969. 

H. Kressel, "Advances in Lasers," ed. A. K. Levine and A. J. DeMaria, Marcel Dekker, N.Y., 1971. 



368 



Handbook of Lasers 



TABLE 12-1. SPECTRAL RANGE COVERED BY SEMICONDUCTOR 

LASERS 





A 

0*) 


hv 
(eV) 




Mode of excitation and reference 




Injection 


Electron 
beam 


Optical Avalanche 


ZnS 


0.33 


3.8 




1 


2 


fZnO 


0.37 


3.4 




3,4 




Z ni _ x Cd x S 


0.49-0.32 


2.5-3.82 






5 


ZnSe 


0.46 


2.7 




6 




fCdS 


0.49 


2.5 




4,7-11 


12 


ZnTe 


0.53 


2.3 




13 




GaSe 


0.59 


2.1 




14 




CdSei_ x S x 


0.49-0.68 


2.5-1.8 




15 


16 


CdSeo.95So.05 


0.675 


1.8 






16 


CdSe 


0.675 


1.8 




4,8,17 


18,19 


tAl!_ x Ga x As 


0.63-.90 


2.0-1.4 


20-29 






tGaA Sl _ x P x 


0.61-0.90 


2.0-1.4 


30-34 


35,36 




CdTe 


0.785 


1.6 




37-39 




tGaAs 


0.83-.91** 


1.50-1.38 


40-42 


43^5 


46,47 48 


InP 


0.91 


1.36 


49-50 




51 


GaAsi_ x Sb x 


0.95-1.5 


1.4-0.83 


* 






CdSnP 2 


1.01 


1.25 




52 




InAsi_ x P x 


0.9-3.2 


1.4-0.39 


* 






InAso.94Po.06 


0.942 


1.32 


53 






InAso.51Po.49 


1.6 


0.78 


53 






GaSb 


1.55 


0.80 


54-56 


57 




In!_ x Ga x As 


0.58-3.1 


2.14-0.4 


58 






Ino.65Gao.35As 


1.77 


0.70 


58 






Ino.75Gao.25As 


2.07 


0.60 


58 






Cd 3 P 2 


2.1 


0.58 






59 


InAs 


3.1 


0.39 


60-63 


64 


65 


InAs!_ x Sb x 


3.1-5.4 


0.39-0.23 


66 






InAso.98Sbo.02 


3.19 


0.39 


66 






Cd^Hg^e 


3-15 


0.41-0.08 




67 


67 


Cdo.32Hgo.6sTe 


3.8 


0.33 






67 


Te 


3.72 


0.334 




68 




PbS 


4.3 


0.29 


69 


70 




InSb 


5.2 


0.236 


71-73 


74 


75,76 77,78 


PbTe 


6.5 


0.19 


79 


70 




PbS!_ x Se x 


3.9-8.5 


0.32-0.146 


80 


81 




PbSe 


8.5 


0.146 


82-85 


70 




PbSnTe 


28 


0.045 


86 






PbSnSe 


8-31.2 


0.155-0.040 


87-89 







* Expected but not observed. 

** Depending on temperature and doping. 

f Have lased at room temperature. 



REFERENCES FOR TABLE 12-1 



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12 Injection Lasers 369 

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31. N. Holonyak, Jr., Trans. TMS-AIME, 230, 276, 1964. 

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33. J. I. Pankove, H. Nelson, J. J. Tietjen, I. J. Hegyi, and H. P. Maruska, RCA Review, 28, 560, 1967. 

34. J. L. Pankove, I. J. Hegyi, Proc. IEEE, 56, 7,24, 1968. 

35. N. G. Basov, O. V. Bogdankevich, P. G. Eliseev, and B. M. Lavrushin, Sov. Phys.— Solid State, 8, 1073, 1966. 

36. L. N. Kurbatov, V. E. Mashchenko, N. N. Mochalkin, A. D. Britov, and A. I. Dirochka, Proc. Int. Conf. Phys. Semicon- 
ductors, Moscow, 1968, p. 587. 

37. V. S. Vavilov and E. L. Nolle, Dokl. Akad. Nauk SSSR, 164, 73, 1965. 

38. V. S. Vavilov, E. L. Nolle, and V. D. Egorov, Sov. Phys.—Solid State, 7, 749 (1965); ibid, 9, 657, 1967. 

39. N. G. Basov, O. V. Bogdankevich, P. G. Eliseev, and B. M. Lavrushin, Sov. Phys.—Solid State, 8, 1073, 1966. 

40. M. I. Nathan, W. P. Dumke, G. Burns, F. H. Dill, Jr., and G. J. Lasher, Appl. Phys. Lett., 1, 62, 1962. 

41. R. N. Hall, G. E. Fenner, J. D. Kingsley, T. J. Soltys, and R. O. Carlson, Phys. Rev. Lett., 9, 366, 1962. 

42. T. M. Quist, R. H. Rediker, R. J. Keyes, W. E. Krag, B. Lax, A. L. McWhorter, and H. J. Zeiger, Appl. Phys. Lett., 1, 91, 
1962. 

43. C. E. Hurwitz and R. J. Keyes, Appl. Phys. Lett., 5, 139, 1964. 

44. D. A. Cusano, Appl. Phys. Lett., 7, 151, 1965. 

45. O. V. Bogdankevich, N. A. Borisov, I. V. Kryukova, and B. M. Lavrushin, Sov. Phys. Semiconductors, 2, 845, 1969. 

46. N. G. Basov, A. Z. Grasyuk, and V. A. Katulin, Sov. Phys. Dokl., 10, 343, 1965. 

47. P. D. Dapkus, N. Holonyak, Jr., J. A. Rossi, F. V. Williams, and D. A. High, /. Appl. Phys., 40, 3300, 1969. 

48. P. D. Southgate, IEEE J. Quant. Electronics, QE-4, 179, 1968. 

49. K. Weiser, R. S. Levitt, Appl. Phys. Lett., 2, 176, 1963. 

50. G. Burns, R. S. Levitt, M. I. Nathan, and K. Weiser, Proc. IEEE, 51, 1148, 1963. 

51. P. D. Southgate and R. T. Mazzochi, Phys. Rev. Lett., 28A, 216, 1968. 

52. F. M. Berkovskii, N. A. Goryunova, V. M. Orlov, S. M. Ryvkin, V. I. Sokolova, E. V. Tsevkova, and G. P. Shpenkov, 
Sov. Phys. Semiconductors, 2, 1027, 1969. 

53. F. B. Alexander, V. R. Bird, D. R. Carpenter, G. W. Manley, P. S. McDermott, J. R. Peloke, H. F. Quinn, R. J. Riley, 
and L. R. Yetter, Appl. Phys. Lett., 4, 13, 1964. 

54. C. Chipaux and E. Eymard, Phys. Stat. Sol., 10, 165, 1965. 

55. I. V. Kryukova, et ah, Sov. Phys. Solid State, 8, 822 and 1538, 1966. 

56. B. Pistoulet and H. Mathieu, Proc. Int. Conf. Phys. Semiconductors, Moscow, 1968, p. 352. 

57. C. Benoit-a-la Guillaume and J. M. Debever, Compt. Rend. 258, 2200, 1964. 

58. I. Melngailis, A. J. Strauss and R. H. Rediker, Proc. IEEE, 51, 1154, 1963. 

59. S. G. Bishop, W. J. Moore and E. M. Swiggard, Appl. Phys. Lett. 15, 12, 1969. 

60. I. Melngailis, Appl. Phys. Lett. 2, 176, 1963. 

61. M. Rodot, P. Leroux Hugon, J. Besson and H. Lebloch, UOnde Electrique, 45, 1197, 1965. 

62. I. Melngailis and R. H. Rediker, /. Appl. Phys. 37, 899, 1966. 

63. M. Rodot, C. Verie, Y. Marfaing, J. Besson and H. Lebloch, IEEE J. Quant. Electronics, QE-2, 586, 1966. 

64. C. Benoit-a-la Guillaume and J. M. Debever, Solid State Commun. 1, 10, 1965. 

65. I. Melngailis, IEEE J. Quant. Electronics, QE-1, 104, 1965. 

66. N. G. Basov, A. V. Dudenkova, A. I. Krasil'nikov, V. V. Nikitin, and K. P. Fedoseev, Sov. Phys. Solid State, 8, 847, 
1966. 

67. I. Melngailis and A. J. Strauss, Appl. Phys. Lett. 8, 179, 1966. 

68. C. Benoit-a-la Guillaume and J. M. Debever, Solid State Commun. 3, 19, 1965. 

69. J. F. Butler and A. R. Calawa, /. Electrochem. Soc. 54, 1056, 1965. 

70. C. E. Hurwitz, A. R. Calawa and R. H. Rediker, IEEE J. Quant. Electronics, QE-1, 102, 1965. 

71. C. Benoit-a-la Guillaume and P. Lavallard, Solid State Commun. 1, 148, 1963. 

72. I. Melngailis, R. J. Phelan, and R. H. Rediker, Appl. Phys. Lett. 5, 99, 1964. 

73. I. Melngailis, Appl. Phys. Lett., 6, 59, 1965. 

74. C. Benoit-a-la Guillaume and J. M. Debever, Solid State Commun., 2, 145, 1964. 

75. R. J. Phelan and R. H. Rediker, Appl. Phys. Lett., 6, 70, 1965. 

76. R. J. Phelan, A. R. Calawa, R. H. Rediker, R. J. Keyes, and B. Lax, Appl. Phys. Lett., 3, 143, 1963. 

77. A. P. Shotov, S. P. Grishechkina, B. D. Kopilovskii, and R. A. Muminov, Sov. Phys. Solid State, 8, 865 and 1998, 1966. 

78. A. P. Shotov, S. P. Grishechkina, and R. A. Muminov, Proc. Int. Conf. Phys. Semiconductors, Moscow, 1968, p. 539. 

79. J. F. Butler, A. R. Calawa, R. J. Phelan, Jr., T. C. Harman, A. J. Strauss, and R. H. Rediker, Appl. Phys. Lett. 5, 75, 1964. 



370 Handbook of Lasers 



80. L. N. Krubatov, A. D. Britov, I. S. Aver'yanov, V. E. Mashchenko, N. N. Mochalkin, and A. I. Dirochka, Sov. Phys. Semi- 
conductors, 2, 1008, 1969. 

81. L. N. Kurbatov, V. E. Mashchenko, N. N. Mochalkin, A. D. Britov, and A. I. Dirochka, Proc. Int. Conf. Phys. Semicon- 
ductors, Moscow, 1968, p. 587. 

82. J. F. Butler, A. R. Calawa, R. J. Phelan, Jr., A. J. Strauss, and R. H. Rediker, Solid State Commun., 2, 303, 1964. 

83. J. F. Butler, A. R. Calawa, and R. H. Rediker, IEEE J. Quant. Electronics, QE-1, 4, 1965. 

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1968, p. 546. 

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87. J. F. Butler, A. R. Calawa, and T. C. Harman, Appl. Phys. Lett., 9, 427, 1966. 

88. T. C. Harman, A. R. Calawa, I. Melngailis, and J. O. Dimmock, Appl. Phys. Lett., 14, 333, 1969. 

89. A. R. Calawa, J. O. Dimmock, T. C. Harman, and I. Melngailis, Phys. Rev. Lett., 23, 7, 1969. 



Insulating Crystal Lasers 

Marvin J. Weber 

Research Division 

Raytheon Company 

Waltham, Massachusetts 02154 

TABLE 13-1. INSULATING CRYSTAL LASER HOSTS 

Further crystallographic data and references can be found in "Crystal Structures" by R. W. G. 
Wyckoff (Interscience Publishers, New York, 1963). Values of lattice constants, density, and other 
properties are from Wyckoff or from the "Handbook of Chemistry and Physics" edited by R. C. 
Weast (The Chemical Rubber Co., Cleveland, 1969). 

Additional information about laser crystals can be found in A. A. Kaminskii and V. V. Osiko, 
Izv. Akad. Nauk SSSR. Neorgan. Materialy, 1, 2049 (1965), ibid., 3, 417 (1967). ibid., 6, 629 (1970), 
and in papers where laser action is reported (see references at the end of this chapter). 

The properties of a number of Nd 3+ laser materials, including references, are reviewed by Thornton 
et ah, Appl. Optics, 8, 1087 (1969). 

The materials in these tables are generally grown either from a melt or from solution. Methods 
for the former include Verneuil (flame fusion), Czochralski (vertical pulling), Bridgman-Stockbarger 
(crucible) and zone melting (floating zone); the latter include flux and hydrothermal techniques. The 
methods of growth indicated are those that have yielded crystals of laser size and quality. 

The growth and chemistry of laser crystals are thoroughly reviewed in a survey by K. Nassau in 
"Applied Solid State Science," Vol. 2, edited by R. Wolfe, Academic Press, New York, 1971, p. 174. 



371 



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13 Insulating Crystal Lasers 389 
TABLE 13-3. INSULATING CRYSTAL LASER WAVELENGTHS 

Because of the large number of Nd 3+ 4 F 3/2 -> 4 In/ 2 wavelengths reported, only those for the more useful hosts are 



given. 



Wavelength 
((Jim) 


Ion 


Host 


Transition 


Temperature 


Reference 


0.5512 


Ho 3 + 


CaF 2 


50 _».5t 


77 


103 


0.5985 


p r 3 + 


LaF 3 


3 Po^ 3 H 6 


77 


33 


0.6113 


Eu 3 + 


Y 2 3 


5 D -> 7 F 2 


220 


100 


0.6193 


Eu 3 + 


YV0 4 


5 D -* 7 F 2 


90 


101 


0.6929 


Cr 3 + 


A1 2 3 


2 E(2A)^ 4 A 2 


290 


9 


0.6934 


Cr 3 + 


A1 2 3 


2 E(E)-* 4 A 2 


77 


7 


0.6943 


Cr 3 + 


A1 2 3 


2 E(E)-> 4 A 2 


300 


1 


0.6969 


Sm 2 + 


SrF 2 


^o^'Fx 


4.2 


21 


0.7009 


Q.3+.Q.3 + 


A1 2 3 


Satellite line (N 2 ) 


77 


11 


0.7041 


Cr 3+ -Cr 3+ 


A1 2 3 


Satellite line (N x ) 


77 


11 


0.7085 


Sm 2 + 


CaF 2 


5d^ 7 F! 


20 


18 


0.720 


Sm 2 + 


CaF 2 


5d-> 7 Fi 


>65 


20 


0.729 


Sm 2+ 


CaF 2 


5d^ 7 F x 


>65 


20 


0.8456 


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CaF 2 


S 3 / 2 ->- Ii 3 / 2 


77 


123 


0.8548 


Er 3 + 


CaF 2 


S3/ 2 ~*" I13/2 


77 


123 


0.9145 


Nd 3+ 


CaW0 4 


F 3 / 2 -> I9/2 


77 


59 


0.946 


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Y 3 A1 5 12 


F3/2 "*■ I9/2 


230 


89 


1.0296 


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Y 3 A1 5 12 


2 F 5/ 2 -»■ 2 F 7 /2 


77 


145 


1.0336 


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Fs/2-^ F 7/2 


~120 


144 


1.0369 


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F 3 / 2 -> In/ 2 


295 


46 


1.04 


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Ca(Nb0 3 ) 2 


^♦-►'H* 


77 


31 


1.047 


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F 3 / 2 -> In/ 2 


300 


67 


1.0457 


Nd 3 + 


CaF 2 


F 3 /2~ *" I11/2 


77 


40 


1.0468 


p r 3 + 


CaW0 4 


1 G 4 ^ 3 H 4 


77 


32 


1.0471 


Nd 3+ 


LiYF 4 


r 3 /2^ Ml/2 


300 


76 


1.0486 


Nd 3+ 


LaF 3 -SrF 2 


F 3 /2~*" I11/2 


300 


69 


1.0506 


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F 3 / 2 -> I11/2 


300 


79 


1.0519 


Nd 3 + 


Y 3 A1 5 12 


r 3 /2^ ill/2 


300 


87 


1.530 


Nd 3 + 


LiYF 4 


r 3 /2^ I11/2 


300 


76 


1.0538 


Nd 3 + 


NaCaYF 6 


F 3/2 ->- In/ 2 


300 


78 


1.0544 


Nd 3 + 


Ba 2 MgGe 2 7 


*F 3/2 ->- 4 Iii/ 2 


300 


38 


1.0584 


Nd 3 + 


CaW0 4 


F 3 / 2 ->- In/ 2 


300 


55 


1.0586 


Nd 3 + 


PbMoO* 


F3/2 - *" I11/2 


295 


36 


1.0612 


Nd 3 + 


Y 3 A1 5 12 


F 3 / 2 ->- In/ 2 


300 


87 


1.0615 


Nd 3 + 


Ca(Nb0 3 ) 2 


F 3 / 2 -* In/ 2 


300 


50 


1.0629 


Nd 3 + 


Ca 5 (P0 4 ) 3 F 


F 3/2 -> In/ 2 


300 


52 


1.0633 


Nd 3 + 


LaF 3 


F 3 / 2 -*■ In/ 2 


300 


67 


1.0641 


Nd 3+ 


YV0 4 


F 3 / 2 -*- In/ 2 


300 


93 


1.0642 


Nd 3 + 


Y 3 A1 5 12 


r 3 / 2 ^ in/2 


300 


63 


1.0645 


Nd 3 + 


YA10 3 


F 3/2 -> In/ 2 


295 


85 


1.0652 


Nd 3 + 


CaW0 4 


r 3 / 2 ->- in/ 2 


295 


36 


1.0673 


Nd 3 + 


CaMo0 4 


r 3 / 2 — »- lll/ 2 


300 


36 


1.0736 


Nd 3 + 


Y 3 A1 5 12 


F 3 / 2 ->- In/ 2 


300 


87 


1.076 


Nd 3 + 


La 2 2 S 


*T7 ■> 4.T 
^3/2^ lll/2 


300 


74 


1.0789 


Nd 3 + 


Gd 2 3 


4 F 3/2 -> In/ 2 


300 


65 



390 



Handbook of Lasers 



TABLE 13-3. INSULATING CRYSTAL LASER WAVELENGTHS (Continued) 



Wavelength 



Ion 



Host 



Transition 



Temperature D r 

(o K \ Reference 



1.079 


Nd 3 + 


La 2 3 


4 T7 - 4T 
r 3/2~^ lll/2 


300 


73 


1.0795 


Nd 3 + 


YA10 3 


4 Tn -, 4-T 

r 3/2^ ill/2 


295 


84 


1.0842 


Nd 3 + 


LiNb0 3 


4-F -*. 4 T 

r 3/2^ All/2 


295 


35 


1.0885 


Nd 3 + 


CaF 2 (II) 


4 T7 -, 4T 

r 3/2^ All/2 


300 


43 


1.1119 


Nd 3 + 


Y 3 A1 5 12 


4-TT _*. 4 T 
^3/2^ All/2 


300 


87 


1.1158 


Nd 3+ 


Y 3 A1 5 12 


4 T7 -. 4t 
r 3/2^ All/2 


300 


87 


1.116 


Tm 2 + 


CaF 2 


Fs/2^- F 7 / 2 


4.2 


128 


1.1213 


y2 + 


MgF 2 


4 T 2 ^ 4 A 2 


77 


13 


1.1225 


Nd 3 + 


Y 3 A1 5 12 


4-T7 ■> 4t 
r 3/2^ ill/2 


300 


87 


1.26 


Er 3 + 


CaF 2 


4c ,, 4t 
"3/2^ Ml/2 


77 


124 


1.3144 


Ni 2 + 


MgO 


3 T 2 -> 3 A 2 


77 


16 


1.319 


Nd 3 + 


Y 3 A1 5 12 


4-T7 ■. 4T 
^3/ 2 ^ A 11/2 


300 


87 


1.3372 


Nd 3 + 


CaW0 4 


F3/2 - * - Ill/ 2 


77 


59 


1.338 


Nd 3 + 


Y 3 A1 5 12 


F 3 / 2 -> Ii 3 / 2 


300 


88 


1.3392 


Nd 3 + 


CaW0 4 


F3/ 2 -*■ I13/2 


295 


59 


1.345 


Nd 3 + 


CaW0 4 


F 3 / 2 ->- Ii 3 / 2 


77 


59 


1.358 


Nd 3 + 


Y 3 A1 5 12 


F 3 / 2 -> Ii 3 / 2 


300 


88 


1.387 


Nd 3 + 


CaW0 4 


4X7 v 4t 
r 3/2-* A13/2 


77 


59 


1.5298 


Er 3 + 


CaF 2 


4 T -^- 4 T 

Al3/2^ A 15 / 2 


4 


122 


1.5308 


Er 3 + 


CaF 2 


4 T -, 4T 
Al3/2^ A15/2 


4 


122 


1.5448 


Er 3 + 


CaF 2 -YF 3 


Il3/2 ~> Il5/2 


77 


126 


1.5558 


Er 3 + 


CaF 2 -YF 3 


4 T ■■ 4T 

Al3/2^ A 15/2 


77 


126 


1.61 


Er 3 + 


Ca(Nb0 3 ) 2 


4 T _v 4 T 

Al3/2^ Ai 5/2 


77 


127 


1.6113 


Er 3 + 


LaF 3 


4-T -, 4T 

Al3/2^ A 15/2 


77 


129 


1.612 


Er 3 + 


CaW0 4 


4 T ■> 4t 
Al3/2^ A 15/2 


77 


128 


1.617 


Er 3 + 


CaF 2 


4 T s 4t 

Al3/ 2 ^" A 15/2 


77 


121 


1.623 


Ni 2 + 


MgF 2 


3 T 2 ^ 3 A 2 


77 


16 


1.636 


Ni 2 + 


MgF 2 


3 T 2 ^ 3 A 2 


77-82 


16 


1.6452 


Er 3 + 


Y 3 A1 5 12 


4 T ■> 4T 

Al3/ 2 ^" Ai 5/2 


77 


131,132 


1.6602 


Er 3 + 


Y 3 A1 5 12 


4 T -i-4-T 

Al3/2^ A 15 / 2 


77 


131 


1.663 


Er 3 + 


YA10 3 


4c - 4T 
"3/2 ^ A 9/2 


295 


130 


1.674-1.676 


Ni 2 + 


MgF 2 


3 T 2 ^ 3 A 2 


82-100 


16 


1.696 


Er 3 + 


CaF 2 


4e _. 4t 
"3/2 ^ A 9/2 


77 


124 


1.715 


Er 3 + 


CaF 2 


4-C _-4t 
"3/2^ A9/2 


77 


124 


1.726 


Er 3 + 


CaF 2 


4c - 4t 
"3/2 ^ A 9/2 


77 


124 


1.731-1.756 


Ni 2 + 


MgF 2 


3 T 2 ^ 3 A 2 


100-192 


16 


1.750 


Co 2 + 


MgF 2 


*T 2 -»' 4 Ti 


77 


14 


1.785-1.797 


Ni 2 + 


MgF 2 


3 T 2 ^ 3 A 2 


77 


16 


1.8035 


Co 2 + 


MgF 2 


4 T 2 ^ 4 Ti 


77 


14 


1.821 


Co 2 + 


KMgF 3 


4 T 2 -> 4 T! 


77 


14 


1.8532 


Tm 3 + 


LiNb0 3 


3 H 4 ^ 3 H 6 


77 


142 


1.8580 


Tm 3 + 


a-NaCaErF 6 


3 H 4 ^ 3 H 6 


77 


143 


1.860 


Tm 3 + 


CaF 2 : ErF 3 : TmF 3 


3 H 4 -> 3 H 6 


100 


133 


1.865 


Ni 2 + 


MnF 2 


3 T 2 -> 3 A 2 


20 


16 


1.880 


Tm 3 + 


EilsYlsAIsO^ 


3 H 4 ^ 3 H 6 


77 


141 



13 Insulating Crystal Lasers 391 
TABLE 13-3. INSULATING CRYSTAL LASER WAVELENGTHS (Continued) 



Wavelength 
(fxm) 


Ion 


Host 


Transition 


Temperature 


Reference 


1.8834 


Tm 3 + 


Y 3 A1 5 12 


3 H 4 ^ 3 H 6 


11 


141 


1.884 


Tm 3 + 


Ei. s Yi. s M s 12 


3 H 4 ^ 3 H 6 


11 


141 


1.8885 


Tm 3 + 


a-NaCaErF 6 


3 H 4 -> 3 H 6 


11 


143 


1.894 


Tm 3 + 


CaF 2 -ErF 3 


3 H 4 ^ 3 H 6 


11 


134 


1.9060 


Tm 3 + 


CaMo0 4 


3 H 4 ^ 3 H 6 


11 


136 


1.91 


Tm 3 + 


Ca(Nb0 3 ) 2 


3 H 4 ^ 3 H 6 


11 


138 


1.9111 


Tm 3 + 


CaW0 4 


H 4 — > H& 


11 


139 


1.915 


Ni 2 + 


MnF 2 


3 T 2 ^ 3 A 2 


11 


16 


1.916 


Tm 3 + 


CaW0 4 


3 H 4 -* 3 H 6 


11 


139 


1.922 


Ni 2 + 


MnF 2 


3 T 2 -> 3 A 2 


11 


16 


1.929 


Ni 2 + 


MnF 2 


3 T 2 ^ 3 A 2 


85 


16 


1.934 


Tm 3 + 


Er 2 3 


H 4 -> He 


77 


140 


1.939 


Ni 2+ 


MnF 2 


3 T 2 ^ 3 A 2 


85 


16 


1.972 


Tm 3 + 


SrF 2 


H 4 — *■ Hg 


77 


140 


1.99 


Co 2+ 


MgF 2 


4 T 2 ^ 4 T! 


77 


15 


2.0132 


Tm 3 + 


Y 3 A1 5 12 


3 H 4 -> 3 H 6 


77 


141 


2.014 


Tm 3 + 


^r ls Y U5 Al s 12 


3 H 4 ^ 3 H 6 


77 


141 


2.019 


Tm 3 + 


Y 3 A1 5 12 


3 H 4 ^ 3 H 6 


295 


141 


2.0312 


Ho 3 + 


a-NaCaErF 6 


5 I 7 ^ 5 I 8 


77 


117 


2.0318 


Ho 3 + 


CaF 2 -YF 3 


5 I 7 ^I 8 


90 


106 


2.0377 


Ho 3 + 


a-NaCaErF 6 


*7 ^ ±8 


77 


117 


2.046 


Ho 3 + 


CaW0 4 


5 T -v 5 T 
I7 ^ ±8 


77 


102 


2.047 


Ho 3 + 


Ca(Nb0 3 ) 2 


5 T -, 5T 

I7 ^ *8 


77 


109 


2.05 


Co 2 + 


MgF 2 


4 T 2 ^ 4 Tx 


77 


15 


2.05 


Ho 3 + 


CaF 2 


5 T — S.5T 


100 


107 


2.0556 


Ho 3 + 


CaMo0 4 


5 T -v 5 T 


77 


108 


2.059 


Ho 3 + 


CaW0 4 


i 7 -*■ i 8 


298 


102 


2.06 


Ho 3 + 


CaF 2 


5 T ■> 5T 

A 7 -^ A 8 


298 


107 


2.0600 


Ho 3 + 


CaF 2 -ErF 3 


17 ~* *8 


77 


105 


2.066 


Ho 3 + 


LiYF 4 


5 I 7 -> 5 l8 


77 


116 


2.0707 


Ho 3 + 


CaMo0 4 


S I 7 -> 5 l8 


77 


108 


2.0740 


Ho 3 + 


CaMo0 4 


S T -^- 5 T 
I7 -> Is 


77 


108 


2.0786 


Ho 3 + 


LiNb0 3 


17 ^ *8 


77 


115 


2.086 


Ho 3 + 


Y 3 Fe 5 12 


5 T -^. 5 T 


77 


120 


2.0905 


Ho 3 + 


Y 3 Fe 5 12 


s i 7 ^ 5 i 8 


77 


120 


2.0914 


Ho 3 + 


Y 3 A1 5 12 


5 i 7 ^ 5 i 8 


77 


113 


2.0917 


Ho 3 + 


Erx.sYx.sAlsO^ 


5 T ■, 5T 

I7 -*■ *8 


77 


113 


2.092 


Ho 3 + 


CaF 2 


5 T -4. St 


77 


102 


2.0975 


Ho 3 + 


Y 3 A1 5 12 


5 T -^ 5 T 
*7^ 18 


77 


113 


2.0979 


Ho 3 + 


EflsYlsAIsO^ 


5 T -^ 5 T 
*7 ^ l 8 


77 


113 


2.0982 


Ho 3 + 


Y 3 A1 5 12 


5T -^- 5T 

1 7 -> 1 8 


77 


118 


2.119 


Ho 3 + 


YA10 3 


5 T -4- 5 T 
l 7 -> 1 8 


77 


153 


2.121 


Ho 3 + 


Er 2 3 


5 T -* 5 T 

lj-*- 1 8 


77 


112 


2.1223 


Ho 3 + 


Y 3 A1 5 12 


5 T -^ 5T 


77 


113 


2.123 


Ho 3 + 


EflsYlsAIjO^ 


l 7 -*■ 1 8 


77 


113 



392 



Handbook of Lasers 



TABLE 13-3. INSULATING CRYSTAL LASER WAVELENGTHS (Continued) 



Wavelength 
{(xm) 



2.1288 

2.165 

2.24 

2.36 

2.407 

2.44 

2.51 

2.556 

2.57 

2.613 

2.69 



Ion 



Ho 3+ 
Co 2+ 

U 3+ 
Dy 2+ 

U 3 + 

U 3 + 

u 3+ 
u 3+ 
u 3+ 
u 3+ 

Er 3 + 



Host 



Y 3 A1 5 12 

ZnF 2 

CaF 2 

CaF 2 

SrF 2 

CaF 2 
CaF 2 
BaF 2 
CaF 2 
CaF 2 

CaF 2 : ErF 3 : TmF 3 



Transition 



5 T ->. 


5T 


4 T 2 ^ 4 T a 


4 T 

Ml/2 


-*■ Ig/2 


S h^ 


5 I 8 


Ill/2 


"** I9/2 


4 T 

Ml/2 


-*" I9/2 


4 T 

All/2 


-»■ 19/2 


4 T 

ill/2 


-*■ I9/2 


Ill/2 


-> 4 T 

-*■ I9/2 


Ill/2 


-> 4 T 

-*■ I9/2 



4 Il VJ ->*Il3 



Temperature 



Reference 



295 
77 
77 
77 
90 

77 

77 

20 

300 

300 

298 



118 
15 

150 
22 

151 

148 
149 
146 
149 
147 

125 



TABLE 13-4. SENSITIZED INSULATING CRYSTAL LASERS 



Laser 


Laser 


Sensitization 


Host 




Figure 
13.8- 


ion 


transition 


ion(s) or group 


crystal 


Reference 


Nd 3+ 


4 F3/2-**Il3/2 


Ce 3+ 


CeF 3 


61,62 








Cr 3+ 


Y 3 A1 5 12 


90 


A 






Cr 3 + 


YAIO3 


86 


A 






(vo 4 ) 3 - 


YVO4 


92 




Ho 3+ 


5 l7-* 5 I 8 


Cr 3 + 


Y 3 A1 5 12 


113 


A 






Cr 3 + 


Ca 5 (P0 4 ) 3 F 


110 


A 






Er 3 + 


CaF 2 -ErF 3 


105 


D 






Er 3 + 


CaMo0 4 


108 


D 






Er 3 + 


Er 2 3 


112 


D 






Er 3 + 


LiYF 4 


116 


D 






Er 3 + 


a-NaCaErF 6 


117 


D 






Er 3 + 


Y 3 A1 5 12 


113 


D 






Er 3+ , Tm 3 + 


Y 3 Fe 5 12 


120 


D 






Er 3+ , Tm 3+ , Yb 3+ 


CaF 2 


104,107 


C, D 






Er 3+ , Tm 3+ , Yb 3 + 


Y 3 A1 5 12 


118 


D 






Er 3+ , Tm 3+ 


CaY 4 (Si0 4 ) 3 


111 


D 






Er 3+ , Tm 3 + 


YA10 3 


153 


D 


Er 3 + 


Il3/2-> 4 Il5/2 


color center 


CaF 2 


122 








Yb 3 + 


Y 3 A1 5 12 


132 


C 


Tm 3+ 


3 H 4 ^ 3 H 6 


Cr 3 + 


Y 3 A1 5 12 


141 


A 






Er 3 + 


CaF 2 : ErF 3 


133,134 


D 






Er 3 + 


CaMo0 4 


136 


D 






Er 3 + 


Er 2 3 


140 


D 






Er 3+ 


Y 3 A1 5 12 


141 


D 






Er 3+ 


a-NaCaErF 6 


143 


D 


Yb 3+ 


2 Fs/2 -*■ 2 F 7/2 


Nd 3 + 


CaF 2 


144 


B 



13 Insulating Crystal Lasers 393 
TABLE 13-5. CONTINUOUS-WAVE INSULATING CRYSTAL LASERS 



Laser 
ion 


Host 


Sensitizer 
ion(s) 


Wave- 
length 
(jim) 


Tempera- 
ture 
(°K) 


Optical 
pump 


Power 
(watts) 


Efficiency* 
(%) 


Refer- 
ence 


IRON GROUP IONS 
















Cr 3 + 


A1 2 3 




0.694 
0.694** 


300 
4.2, 77 


Hg 
Ar laser 


2.4 


~0.1 


5,6 

12 


Ni 2 + 


MgF 2 




1.67 


85 


W 


1 


0.2 


17 


Ni 2 + 


MnF 2 




1.93 


85 


W 






17 


D1VALENT RARE EARTH IONS 


Dy 2+ 


CaF 2 




2.36 
2.36 


77 
27 


W 

sunlight 


1.2 


0.06 


23 
26 


Tm 2+ 


CaF 2 




1.12 


27 


Hg 






30 


TRIVALENT RARE EARTH IONS 


Nd 3+ 


Ca(Nb0 3 ) 2 




1.06 


300 


Xe 


0.12 


0.05 


152 


Nd 3+ 


Ca 5 (POJ 3 F 




1.06 


300 


W 


1.3 


0.2 


53 


Nd 3 + 


CaW0 4 




1.06 


300 


Xe 


<0.1 


~0.01 


55 








1.06 


300 


Hg 


~0.01 


~0.01 


57 








1.06 


85 


Hg 


0.5 


0.03 


58 


Nd 3+ 


LaF 3 




1.04 


300 








68 


Nd 3+ 


YA10 3 




1.08 


300 








84 








1.06 


300 


Kr 


6.5 


~0.5 


156 


Nd 3+ 


Y 3 A1 5 12 




1.06 


300 


W 


~25 


1.0 


94 








1.06 


300 


Kr 


250 


2.1 


95 








1.06 


300 


Kr 


llOOf 


2.0 


99 








1.06 


300 


plasma arc 


200 


0.2 


96 








1.06 


300 


Na-doped Hg 


0.5 


0.2 


97 








1.32 


300 


W 


0.03 


~0.01 


87 






Cr 3 + 


1.06 


300 


Hg 


10 


0.4 


98 


Ho 3 + 


CaF 2 


Er 3+ , Tm 3+ , Yb 3+ 


2.1 


77 


Xe 






104 


Ho 3 + 


Er 2 3 


Er 3+ 


2.12 


77 


W 






112 


Ho 3+ 


ETKjYLsAlsOja 


Er 3+ 


2.10 


85 


Hg,W 






113 


Ho 3 + 


Y 3 A1 5 12 


Cr 3 + 


2.10 


85 


W 






113 






Cr 3+ 


2.12 


85 


Hg,W 






113 






Er 3+ , Tm 3+ 


2.12 


85 


W 


15 


5 


118 


Tm 3 + 


CaF 2 


Er 3+ 


1.9 


77 


Xe 






135 


Tm 3 + 


Er 2 3 


Er 3 + 


1.93 


77 


W 






140 


Tm 3 + 


EtlsYlsAIsOw 


Er 3+ 


2.01 


85 


W 






141 


Tm 3 + 


Y 3 A1 5 12 




2.01 


85 


W 






141 






Cr 3+ 


2.01 


85 


Hg,W 






141 


ACTINIDE IONS 


U 3+ 


CaF 2 




2.61 


77 


Hg 


10" 5 




147 


* Over-all efficiency : laser output/electrical energy input to pump lamp. Because the efficiency depends upon a number of factors such 
quality, pump cavity efficiency, and output coupling efficiency, the original references should be consulted when comparing values 
** Nonspiking, single-mode operation. 
t Multiple laser rods in series inside one resonant cavity. 


as rod 



394 



Handbook of Lasers 



150 



100 



50 



E in I0 3 cm" 1 



OUta 




- 2000 



H 3000 

4000 
5000 

_ - 10000 



La C« Pr Nd Pm 

Fig. 1 3-1 . Schematic diagram of the 4f" (white) and 4f" ~ x 5d (black) configuration of divalent rare-earth ions. 154 



13 Insulating Crystal Lasers 395 



Yb 
f" 
Tm 
f' 5 

Er 
f' 2 

Ho 
f" 

Dy 

f lO 

Tb 
!• 

6d 
f 

Eu 



Sm 
f« 

Pm 
f 8 

Nd 
f 4 
Pr 
f s 
C« 
f 2 



10,000 



(cm-')' 
20,000 



30,000 40,000 



T 



T 



% 



2F ( 



*/ 2 



3 H . 3 | H » 



^YKS* 



6h.«. 6 Hi&- 6 P 7/ 
%| 2 ) ^ 




A AA/ 



'■A f'- 



»H 



± 



'^v V 



Fig 
itions of 



10,000 20,000 30,000 40,000 

(cm-')—— 

. 13-2. Absorption spectra of divalent rare-earth ions in CaF 2 . The pos- 
f ->f transitions are indicated by arrows. 155 



396 



Handbook of Lasers 




-4000 
-5000 

— -10000 

Ce Pr Nd Pm Sm Eu Gd Tb Ity "So *Ex Tm Yb Lu 

Fig. 13-3. Schematic diagram of the 4f" (white) and 4f- 1 5d (black) configuration of trivalent rare-earth ions. 154 



13 Insulating Crystal Lasers 397 



'e 

o 

19 

o 



?3<0*C\JOOO<O^-CNJOCO<£>^-C\JOOO<0*CVJO 
WlOlOlOlOMNM CM CM — — — — — 

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o 



— — CMtO K> «*» » 

I I II I I I 

£|CM «n|<M tq|N »>|«l =|fM M «>|CM 0»|*J ^\t» El*" 






tt--**tt*Ftf *+ I I I Ira 

III II I INI I I I I I lr *S 



o x a -i 



* wlc* «l~ H «„ § 

IHIHIh I IF HIH#1*| I I 1/ " 



Oca 
0> 



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x>«— ae 

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f-Jc*l 

Me* io|*J 

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m|csi 


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a en 






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1 ► ► 




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ip uu a < o a. o ae *— > a x >-n q 

= u- a to => w 

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■tlOlOfOlOlOCMCMCMCMCM — — — — — w 

T E 

o 
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398 



Handbook of Lasers 



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13 Insulating Crystal Lasers 399 





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=1 

CM 



262i7 F , -f 



15. 

2 



13 
2 



7R 
Sm 



o 



2F. 



*/t 



(0 

to 
oi 

2^1 



4 I 



4. 



50 ia. 340 *»*- 



34.0J 




PHONONS 




ro 
<0 



HI4 ' 

2 
o 

•2 > 

K 
"OS 

UJ 



Tm 



2* 



Dy 



t 



'* 

u 84 - 



3 A f «T, *A 2 

Ni Co 8,1, Cr 3 * 

(MgF,) (M«F 2 ) (Al 2 9 ) 

Fig. 13-7. Energy levels and laser transitions of divalent rare-earth, actinide, and transition metal ions. 157 



414 



Handbook of Lasers 



20 



15 






U 



15- 



SlO 



0) 

c 

UJ 



OL 



Cr° Nd° Ho° Trrr 



2 E 1^^, _==._. 



^2< 



l /2 



A- ll/ 2 



i- 5 I, 



, 3, 



Yb' 



3+ 



Ho 3+ Er 3+ 



Tm" 



3+ 




Nd 3 * Yb 3+ 



w- 2 . 



^ 



13 



H/2- 
9 /o- 



'5/2 



— — Energy transfer 

— Rapid cascade 

— Laser transition 



2 C 



Er 



3+ 



'7/2 



Ho 3+ Tm 3+ 



n/2 p 



T I3/A^; 



-15/2 



\ 



f/2 "° _| 5/2 

Fig. 13-8. Diagrams of energy cascade and transfer for sensitized laser schemes. 

A: Cr 3+ -*Nd 3+ , Cr 3+ -»Ho 3+ , Cr 3+ ->Tm 3+ ; 

B:Nd 3+ -*Yb 3+ ; 

C: Yb 3+ -^Ho 3+ , Yb 3+ -*Er 3+ , Yb 3+ -*Tm 3+ ; 

D: Er 3+ ^Tm 3+ , Er 3+ -*Ho 3+ , Tm 3+ ->Ho 3+ . 



^ 3 H 4 



'He 



13 Insulating Crystal Lasers 415 



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416 Handbook of Lasers 

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1969. 

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139. L. F. Johnson,/. Appl. Phys. 34, 897, 1963. 

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142. L. F. Johnson and A. A. Ballman, /. Appl. Phys. 40, 297, 1969. 



13 Insulating Crystal Lasers 417 

143. Kh. S. Bagdasarov, A. A. Kaminskii, and B. P. Sobolev, Izv. Akad. Nauk. SSSR, Ser. Neorg. Mat. 5, 617, 1969. 

144. M. Robinson and C. K. Asawa, /. Appl. Phys. 38, 4495, 1967. 

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146. S. P. S. Porto and A. Yariv, Proc. IRE, 50, 1542, 1962. 

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323, 1970. 

153. M. J. Weber and M. Bass, E. Comperchio, and L. A. Riseberg. To be published. 

154. G. H. Dieke and H. M. Crosswhite, "The spectra of the doubly and triply ionized rare earths," Appl. Optics, 2, 675-686, 

155. D. S. McCiure and Z. J. Kiss, " Survey of the spectra of the divalent rare-earth ions in cubic crystals," in " Optical Masers " 
J. Fox, Ed., pp. 357-368, Polytechnic Press, Brooklyn, 1968. 

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Laboratory, 1970. 

157. D. S. McCiure and Z. J. Kiss, /. Chem. Phys. 39, 3251, 1963. 



Section 4" 

Laser Resonators 



Beams, Modes and Resonators* 



Herwig Kogelnik and Tingye Li 

Bell Telephone Laboratories, Incorporated 
Holmdel, New Jersey 07733 



PARAXIAL RAYS 



The passage of paraxial rays through linear optical structures can be described by ray transfer 
matrices. Paraxial rays are rays which have small slopes with respect to the optic axis. As indicated in 
Figure 14-1, a paraxial ray in a given cross-section (z = const) of the structure is characterized by its 
distance x from the optic (z) axis and by its angle or slope x' with respect to that axis. The ray matrix, 
or "y4i?CD-matrix," relates the input quantities x t and x\ to the output quantities x 2 and x' 2 by 



x 2 


= 


A B 
C D 


Xy 



The matrix elements generally satisfy the relation 

AD-BC= 1. 




Fig. 14-1. Reference planes of an optical system. A typical ray 
path is indicated. 

The matrix elements are related to the focal length /of the system and to the location of the principal 
planes by 



h 2 = 



D-\ 

C 
A- 1 



* Most of the following material is based on the review article " Laser Beams and Resonators," which appeared 
jointly in Appl. Optics, 5, 1550, October, 1966 and in the Proc. IEEE, 54, 1312, October, 1966. This article should be 
consulted for further details, explanations, derivations and references. 

421 



422 



Handbook of Lasers 



where h ± and h 2 are the distances of the principal planes from the input and output planes, as shown 
in Figure 14-1. 

Table 14-1 lists the ray transfer matrices of six elementary optical structures. The matrix of No.l 
describes the ray transfer over a distance d. No. 2 describes the transfer of rays through a thin lens of 
focal length/. Here the input and output planes are immediately to the left and right of the lens. No. 3 
is a combination of the first two. It governs rays passing first over a distance d and then through a thin 
lens. If the sequence is reversed the diagonal elements are interchanged. The matrix of No. 4 describes 
the rays passing through two structures of the No. 3 type. The ray transfer matrix for a lenslike medium 
of length d is given in No. 5. In this medium the refractive index varies quadratically with the distance 
r from the optic axis. 



n = n — A 



$n 2 r 



The matrix of a dielectric material of index n and length d is given in No. 6. The matrix is referred to 
the surrounding medium of index 1. 



LASER BEAMS 

Gaussian Beams 

Laser beams behave, in many respects, similarly to uniform plane waves ; however, their intensity 
distributions are not uniform, but are concentrated near the axis of propagation and their phase fronts 
are slightly curved. A laser oscillating in a fundamental transverse (TEM 00 ) mode produces a beam 
with a transverse amplitude distribution that is approximately Gaussian in every cross-section of the 
beam. This is illustrated in Figure 14-2. 



■ 


'E 




1 /~ 




i ^ 


*— w — *■ 


\ E °'/ e 






r 



Fig. 14-2. Amplitude distribution of the fundamental beam. 

BEAM RADIUS. The width of the beam is measured by the "beam radius" w. This is defined 
as the distance at which the field amplitude is l/e times that on the axis. 

BEAM EXPANSION. A Gaussian beam contracts to a minimum diameter 2w at the beam waist 
where the phase front is plane. The beam expands with the distance z from the waist according to 

w 2 (z) = w 2 [l+(Xzlnwl) 2 ] 
The resulting beam contour w(z) is illustrated in Figure 14-3. The far field diffraction angle 9 is given by 

6 = A/nw . 
The radius of curvature R of the wavefront changes according to 

R(z) = z[\ + (nw 2 /lz) 2 ]. 

As the beam propagates, R varies from infinity at the waist to a minimum of 2?,,,^ = 2nwl/X at z = 
izw\\X and approaches z asymptotically. Also, the beam experiences a phase shift O relative to an ideal 
uniform plane wave; it is a phase advance and is given by 

O = arc tan (Xz/nwl). 



14 Beams, Modes and Resonators 423 

TABLE 14-1. RAY TRANSFER MATRICES OF SIX ELEMENTARY 

OPTICAL STRUCTURES 



NO OPTICAL SYSTEM 



1+ d ^ 



1« d »J 



-d r 



d 2 --*< 



t—fc 



iu_____d » 



&& 



i ^*^ - iyavr^ 




RAY TRANSFER MATRIX 



-f 



1-^ d, + d 2 - 



d|d 2 
f, 



i t c<2 d t d 2 d| d|d 2 



cosd 



'M 



' *~d./P 



/n n 2 



. V rvr 2 s. N dyni cosd yg 



d/n 



424 Handbook of Lasers 




/phase front 
Fig. 14-3. Contour of a Gaussian beam. 

COMPLEX BEAM PARAMETER. The real beam parameters w and R are used to define a 
complex beam parameter q 

1_ j__ .J_ 
q~ R J nw 1 ' 

Using the q parameter the laws of beam propagation simplify to 

q 2 = q ± + z, 

where q 1 and q 2 refer to the input and output planes respectively, and z is the distance between these 
planes. 

EFFECT OF LENS. A thin lens of focal length /transforms the q parameters according to 

_L_ l l 

<i2~ qi f' 

where q t and q 2 are measured immediately before and after the lens. 

ABCD-LAW. The input (q ± ) and output (q 2 ) parameters of a laser beam passing through a general 
optical system characterized by its ABCD matrix are related by 

Aq ± + B 
q2 ~Cq t + D' 

Mode Matching 

For matching the modes of one optical structure to those of another, one often needs to transform 
a given Gaussian beam into another prescribed Gaussian beam. This transformation can be accom- 
plished with a thin lens, as indicated in Figure 14-4. The focal length/of this lens must be larger than a 
characteristic length / defined by the confocal parameters b x and b 2 of the two beams as 

/o 2 = #>ib 2 . 

The confocal parameters are related to the waist diameters 2m>! and 2w 2 of the beams by 

b 1 = 2nw\IX, b 2 = 2nw\\X. 

For matching, the distances d x and d 2 between the lens and the beam waists are adjusted to be 

4 =/± ±W(/ 2 //o ) " 1 

rf 2 =/±iW(/ 2 //o)-l> 
where one can choose to use either both plus signs or both minus signs. 



14 Beams, Modes and Resonators 



425 




---dj 



Fig. 14-4. Distances and parameters for a beam transformed 
by a thin lens. 

Table 14-2 lists formulas for the parameters of the exit beams that correspond to the modes of 
various optical structures. They are the confocal parameter b and the distance t, which gives the waist 
location of the emerging beam. System No. 1 is a resonator formed by a flat mirror and a spherical 
mirror of radius R. System No. 2 is a resonator formed by two equal spherical mirrors. System No. 3 
is a resonator formed by mirrors of unequal curvature. System No. 4 is a resonator formed by two 
equal spherical mirrors, with the reflecting surfaces deposited on planoconcave optical plates of index n. 
These plates act as negative lenses and change the characteristics of the emerging beam. System No. 5 
is a sequence of thin lenses of equal focal lengths/. System No. 6 is a system of two irises with equal 
apertures spaced at a distance d. Shown are the parameters of a beam that will pass through both irises 
with the least possible beam diameter. This is a beam which is "confocal" over the distance d. This 
beam will also pass through a tube of length d with the optimum clearance. A similar situation is shown 
in System No. 7, which corresponds to a beam that is confocal over the length d of optical material 
of index n. System No. 8 is a spherical mirror resonator filled with material of index n, or an optical 
material with curved end surfaces, where the beam passing through it is assumed to have phase fronts 
that coincide with these surfaces. 



Circle Diagrams 

The propagation of Gaussian laser beams can be represented graphically on circle diagrams or 
" beam charts." There one can follow a beam as it propagates in free space or passes through lenses. 
The charts contain the beam parameters w, R, w , and z defined above in the section on Gaussian 
beams, and the confocal parameter b = 2nw%/A. The chart proposed by Collins is plotted in the complex 
plane of 



nw 



X 1 



R 



and is shown in Figure 14-5. In this plane lines of constant b/2 = nw\\\ and lines of constant z appear 
as circles through the origin. A beam is represented by a circle of constant b, and the beam parameters 
w and R at a distance z can be read off the coordinate axes. When the beam passes through a lens of 
focal length/, the phase front is changed and a new beam is formed. In the diagram this is represented 
by a vertical line of length 1//, which connects the circles corresponding to the input and output 
beams. The angle O shown in the figure is equal to the relative phase shift O experienced by the beam, 
as given above. 

The chart proposed by Li is the dual to the Collins chart and plotted in the complex plane of 

b 

The sets of circles of both diagrams have the same form, and only the labeling of the axes and circles 
is different. In Figure 14-6 both diagrams are unified in one chart. The labels in parentheses correspond 
to the chart proposed by Li, and 5 is a normalizing parameter, which can be arbitrarily chosen for 
convenience. 



426 Handbook of Lasers 



TABLE 14-2. FORMULAS FOR THE CONFOCAL PARAMETER 

AND THE LOCATION OF BEAM WAIST FOR VARIOUS 

OPTICAL STRUCTURES 



OPTICAL SYSTEM 



t 



d-- 



-d L - 



h--d- 
t 



1-4- 



r -d- 



1-* 



r 



JT^ dl 



£ b = 77W 2/\ 



vZd(R-d) 



lydf 2 R-d) 



/d(R,-dXRa-dXR,+R 2 -d) 



Ri+R 2 -2d 



R n 



r - t?ffc*- 



f f f 



Immwy.mmal 



di 



Ryd( 2R -d) 

2R+d(n*-i) 



iv^ 5 ) 



i- 



d(R 2 -d) 
Ri+R 2 - 2d 



ndR 



2R+d(n 2 -i) 



Td 



T* 



h-- d ^H 



3sb 



■di- 






\*- d ZZ*t A- 
-*i t k- 






WLl 



_d_ 

2n 



nRyd(2R-d) 
2n*R-d(n*-t) 



id 



_d_ 



dR 



2n 2 R-d(n 2 -i) 



1 

R 


I 






i 




"»^Z:>0 




i 
i 

z 
1 
1 

1 
1 


1/ '*/ 






+ 


/L-^^t 










1 \ 


77 






_y i 


Z<0 



\ 

77 WX 



~J 



Fig. 14-5. Geometry for the W-plane circle diagram. 
GAUSSIAN BEAM CHART 

2b/k»* (OR b/b ) 



m ______^_ zb/*«« l or b/b I I 

""l""!" 1 '!""!""!""!""!"" !""!"" ! "" ! "" ! ""!"" ! "" ! ""!"" ! ""!"" ! "" 

2 0.4 0.6 0.8 i.o 1.2 

^^pHlkSe SHIFT IN OeGf»ee s 



2.0 




' " lllllll l lllllll llllllllllllllilliliiliiillillilllllliiiiliiiiliiiiliiiill.iil,i.,lii.. » l iMliiii | 

2b/kv* (OR b/b) 1 

Fig. 14-6. 



428 



Handbook of Lasers 



Other circle diagrams include those proposed by Gordon which allow the graphic determination 
of resonator parameters (see below for definitions). 

Table 14-3 gives a comparison of the parameters that appear in the various circle diagrams. 

TABLE 14-3. PARAMETERS OF BEAM CHARTS 





Collins 


Li 


Gordon 




Parameter plotted 

as ordinate 
Diameter of circles 


l/R 


z 


9i 


92 


centered on ordinate 
Parameter plotted 

as abscissa 
Diameter of circles 


Hz 

X/7TW 2 


R 

TTWllX 


Vff2 

Xd/irw 2 


l/gi 
Xd/irwi 


centered on abscissa 


XJTTWq 


TTW 2 /X 


TTWljXd 


TrwljXd 



LASER RESONATORS 

The resonators used in laser oscillators usually take the form of an open structure consisting of a 
pair of spherical mirrors facing each other, as shown in Figure 14-7. The mirror spacing is d, and the 
radii of curvature of the mirrors are R x and R 2 . 



—J 



«+— 1, 1 




Fig. 14-7. Mode parameters of interest for a resonator with 
mirrors of unequal curvature. 



Stability 

A resonator is stable if 



°<KK->8 



<1. 



In a stable resonator, ray bundles traveling back and forth between the mirrors are periodically re- 
focused so the energy remains in the resonator. However, no refocusing occurs in unstable resonators 
and so a relatively large part of the energy escapes from the resonator on each transversal. 

STABILITY DIAGRAM. In the diagram of Figure 14-8 each resonator type is represented by a 
point. Unstable systems are represented by points in the shaded areas. 

Resonator Types 

Resonator types are distinguished by the mirror curvatures and the relative mirror spacing. For 
example: 

CONFOCAL RESONATOR: R 1 = R 2 = d 
PLANE PARALLEL RESONATOR: R 1 = R 2 =od 
CONCENTRIC RESONATOR: R 1= R 2 = d/2 
HEMISPHERICAL RESONATOR: R 1 = oo, R 2 = d 



14 Beams, Modes and Resonators 429 




Fig. 14-8. Stability diagram. Unstable resonator systems lie 
in shaded regions. 



Resonator Modes 

A mode of a laser resonator is defined as a slowly decaying electromagnetic field configuration 
whose relative distribution does not change with time. It can be represented by a wave propagating 
back and forth between the mirrors. 

DIFFRACTION LOSSES. The modal field decays because the resonator is an open structure 
and light escapes from it. The loss can be thought of as due to diffraction at the finite apertures of the 
mirrors when the wave propagates back and forth in between. 

FUNDAMENTAL BEAT FREQUENCY. The frequency spacing v between neighboring 
(longitudinal) resonances of the laser cavity is 



v = c/2d, 



where c is the light velocity. 



The Integral Equations of Laser Resonators 

Within the approximations that the mirrors are large compared to the wavelength and that the 
field in the resonator is substantially transverse electromagnetic, the Fresnel-Kirchhoff formulation of 
Huygen's principle can be used to derive integral equations that relate the fields at the two opposing 
mirrors of the resonator; the solutions to the equations are the modal fields and their losses. In general, 
the equations take the form 

yCDtfi)^ = f K^\ Sl ,s 2 )E^\s 2 )dS 2 

where the integrations are taken over the mirror surfaces S 2 and S lt respectively. The subscripts and 
superscripts one and two denote mirrors one and two ; s ± and s 2 are symbolic notations for transverse 
coordinates on the mirror surface, e.g., s t = (x lt y t ) and s 2 = (x 2 ,y 2 ) or s t = (r x , ^ t ) and s 2 = (r 2 , <f> 2 ); 
E w and .E (2) are the relative field distribution functions over the mirrors; y (1) and y (2) give the attenua- 
tion and phase shift suffered by the wave in transit from one mirror to the other; the kernels AT (1) and 
K (2) are functions of the distance between s t and s 2 and, therefore, depend on the mirror geometry; 



430 



Handbook of Lasers 



they are equal [K (1 \s 2 , Sl ) = K C2 \s 1 ,s 2 )] but, in general, are not symmetric [J^fo,^) * K (1) (s u s 2 ), 
K«X Sl ,s 2 )*K«\s 2 ,s x )l 

ORTHOGONALITY OF THE MODES. The field distribution functions corresponding to the 
different mode orders are orthogonal over their respective mirror surfaces; that is 

f E^XsMKsJdS^O, m±n 

f E™( S2 )Ei 2 Xs 2 )dS 2 =0, m*n, 

J s 2 

where m and n denote different mode orders. It is to be noted that the orthogonality relation is non- 
Hermitian and is the one that is generally applicable to lossy systems. 

MODE NUMBERS. The modes are distinguished by their mode numbers, which are m, n, and q 
for rectangular geometries and p, I, and q for cylindrical geometries. The mode number q measures 
the number of field zeros of the standing-wave pattern along the z axis. In a rectangular geometry, the 
transverse-mode numbers m and n measure the field nodes in the x and y directions. In a circular 
geometry the transverse mode numbers p and / measure the nodes in the r and (j> coordinates. 

INTEGRAL EQUATIONS FOR RESONATORS WITH SPHERICAL MIRRORS. When the 
mirrors are spherical and have rectangular or circular apertures, the two-dimensional integral equations 
can be separated and reduced to one-dimensional equations. In the case of rectangular mirrors, the 
one-dimensional equations in Cartesian coordinates are the same as those for infinite-strip mirrors; 
for the x coordinate, they are 



yiVfai) = f 2 K(x 1 ,x 2 )u (2 \x 2 )dx 2 

J -a 2 

)4 2) « (2) (x 2 ) = C Kix^xJu^XxJdxt, 

J —n. 



where the kernel K is given by 



K(x u x 2 ) =* J^>expj - ^(g^ 2 + g 2 x\ - lx x x 2 y\. 



Xd 



2d 



Similar equations can be written for the y coordinate, so that E(x,y) = u(x)v(y) and y = y x y,. As 
shown in Figure 14-9 a x and a 2 are the half-widths of the mirrors in the x direction, d is the mirror 




OPAQUE ABSORBING SCREENS 



-2a 



• - — d 



2 W-~tJ) 2 ii-f 



Fig. 14-9. Geometry of a spherical-mirror resonator with finite mirror 
apertures and the equivalent sequence of lenses set in opaque absorbing screens. 



14 Beams, Modes and Resonators 431 

spacing, k is 2n/X, and k is the wavelength. The radii of curvature of the mirrors R t and R 2 are con- 
tained in the factors 

In the case of circular mirrors the equations are reduced to a one-dimensional form by using 
cylindrical coordinates and by assuming a sinusoidal azimuthal variation of the field; that is, E(r, 4>) = 
R 1 (r)e~ jl ' 1 '. The radial distribution functions i?[ 1} and R ( t 2) satisfy the one-dimensional integral 
equations : 



vFWXr&fc = C U? lt r 2 )R?\r 2 )J7 2 dr 2 

y\ 2) R?\r2)Jr~ 2 = C Ur x , r 2 )R\'\r x )^[ dr„ 

where the kernel K x is given by 

Klr u r 2 ) = J —J^ Ji(k rj fy ^r~ 2 expj- J ^{sA + 9 * r % 

and J i is a Bessel function of the first kind and /th order. Here a x and a 2 are the radii of the mirror 
apertures and g x and g 2 are defined as above. 

FRESNEL NUMBER N. The Fresnel Number N is defined as 

N = a x a 2 \Xd. 

It is a key parameter in the solution of the above integral equations. 

Approximate Mode Patterns 

Within certain approximations the modes of spherical mirror resonators are TEM waves with the 
transverse distributions given below. The approximations are valid for stable resonators, and as long 
as the predicted energy distribution is well confined within the apertures of the mirrors. 

MODE PATTERNS FOR RECTANGULAR GEOMETRY. Rectangular geometry can be im- 
posed by mirrors of square or rectangular aperture. For this geometry the transverse field distribution 
E(x, y) of a TEM mn9 mode is approximately described by 

E(x, y) = EoH^JlxMH^y/w) exp(- ^-^)' 

where E is a constant amplitude factor. H n (x) is the Hermite polynomial of nth order defined by 

H n (x) = (-iye* -e ="!£ o v!( „_ 2v) , > 

where [n/2] = n/2 or (« — l)/2, according to whether n is even or odd. Some Hermite polynomials of 
low order are 

H {x) = 1 
H x (x) = 2x 
H 2 (x) = 4jc 2 - 2 
H 3 (x) = 8x 3 - 12* 

The parameter w which appears in these expressions is the beam radius or spot size; formulas 
for w will be given below. Observed mode patterns of some of the lower order modes are shown in 
Figure 14-10a. 



432 



Handbook of Lasers 




TEM, 



TEM, 



TEM 20 




TEMjo 



TEM. 



TEM50 




TEM 2 



Fig, 14-10a. Mode patterns of a gas laser oscillator (rectangular 
symmetry). 

MODE PATTERNS FOR CIRCULAR GEOMETRY. In systems with a circular geometry, 
cylindrical coordinates (r, <£, z) are used. The transverse field distribution E(r, <f>) of a TEM plq mode is 
approximately given by 

where w is again the beam radius. L' p (x) is the generalized Laguerre polynomial defined by 

e*x~ l d p 
L t Jx) = —---(e-*xP +l ) 



p\ dx p 



v = o \p - V/ 



Some low-order Laguerre polynomials are 

L l (x) = I 

L[(x)=l+\-x 

L l 2 (x) = K/ + !)(/ + 2) - (/ + 2)x + ±x 2 - 

Modes of circular geometry are not commonly observed in practice unless the resonator is carefully 
adjusted to be axisymmetric. Some of the observed low-order modes are shown in Figure 14-10b. 



14 Beams, Modes and Resonators 



433 




TF.M, 



TEM ( 



TEM, 




TEM 04 



Fig. 14-10b. Mode patterns of a gas laser oscillator (circular sym- 
metry). From W. W. Rigrod, Appl. Phys. Lett. 2, 51, Feb. 1963. 



Beam Size and Cavity Resonances 

The beam radius w appears as a scaling parameter in the mode patterns above. This section gives 
formulas for the beam radii of various resonator structures of the type shown in Figure 14-7. Also 
given are the resonant frequencies v of the cavity modes. The expressions are written here for the modes 
of rectangular geometry with the mode numbers m and n. For circular geometries the resonant con- 
ditions are obtained by replacing (m + n + I) by (2p + / + 1). 

CONFOCAL RESONATORS (d = R l = R 2 = b). The beam radius w at the mirrors is given by 

and the waist radius w by 
The resonant condition is 



Wq = Abj2n. 



v/v = (?+l) + (m+«+l)/2. 
SYMMETRIC RESONATORS (R r = R 2 = &)• The beam radius w at the mirrors is given by 



(t)AR- 



The beam radius w in the center of the resonator, where the phase front is plane, is given by 



The resonant condition is 



wl=- y /d(2R-d). 



v/v = (q + I) + - (m + n + l)arc cos(l - d/R). 



Figure 14-11 shows the variation of the beam radii with djR for a fixed mirror spacing d. The beam 
radii are normalized to w 0c , the confocal waist radius, defined by 

w^ = Xdjln. 

Figure 14-12 shows the variation of the beam radii with d/R for a fixed mirror curvature. Here w 0e 
is defined by 

w 2 Qc = XRjln. 



434 



Handbook of Lasers 

4 



O 
O 











1 




































d = CONST 


















































































































































































w/w oc 


















































































^b /w oc 















































































0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 20 

d/2f=d/R 
Fig. 14-11. Beam radii as a function of d/R for fixed mirror 
spacing. 



° 3 
o ° 

\ 





















































































































































R=2f= CONST 


























































































































































W/W 0C^ 
























































w /w oc 






































"— - 

































































0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 
d/2f = d/R 

Fig. 14-12. Beam radii as a function of d/R for fixed mirror 
curvature. 



RESONATORS WITH MIRRORS OF UNEQUAL CURVATURE. The beam radii w ± and w 2 at 
the mirrors are given by 

w\ = (XRJn) 2 ^4 i - 

1 17 ' R x - d R t + R 2 - d 

wj = (XR 2 /n) 2 ^^4 v 

2 v 2I ' R 2 -d R t +R 2 -d 

The diameter of the beam waist 2w , which is formed either inside or outside the resonator, is given by 



K 



-© 



X\ 2 d(R x - d){R 2 - d)(R 1 + R 2 -d) 



(i?i + R 2 - 2d) 2 

The distances t x and t 2 between the waist and the mirrors, measured positive as shown in Figure 14-7, 
are 

d(R 2 - d) 



U = 



U = 



R x +R 2 - 2d 

d(R x - d) 
Rt+R 2 - 2d' 



14 Beams, Modes and Resonators 



435 



The resonant condition is 

v/v = (q + 1) + - (m + n + l)arc cosV(l - d/RJil - d/R 2 ), 

where the square root should be given the sign of (1 - d/RJ, which is equal to the sign of (1 - d/R 2 ) 
for a stable resonator. 

Polarization of the Modes 

Field patterns of linearly polarized modes are shown in Figure 14-13. Since the modes are approxi- 



t 




f ! * 




* ; t ; ♦ 


♦ I ♦ 




♦!♦!♦!♦ 




*l*it|ti*l* 


t 




t|» 




i 1 1 ' * 



TEM 00 




TEM, 




TEM 20 


* 1 ♦ 

"♦"TV" 




t i I 

1\V 




h- - 



TEM C 



TEM„ 



TEM 2( 



• 1 ♦ 




1 


t 




J_li.Lt. 


♦ t ♦ 




t 


I 




l!tU 


♦ 1 ♦ 




1 


t 




"tT'Tt" 



TEM 02 TEM, 2 TEM a 

SQUARE MIRRORS 




TEM 20 



CIRCULAR MIRRORS 



Fig. 14-13. Linearly polarized resonator mode configurations for square and 

circular mirrors. 

mately TEM, the arrows represent the direction of either the electric or the magnetic fields. 

Figure 14-14 gives an example of how different polarization configurations can be synthesized 
from the TEM 01 mode of Figure 14-13. 






® 







Fig. 14-14. Synthesis of different polarization con- 
figurations from the linearly polarized TEM i 
mode. 



436 



Handbook of Lasers 



Exact Mode Patterns for N = 1 

The mode patterns obtained from a numerical solution of the resonator integral equation are 
shown below. They are for the case of symmetrical resonators with circular mirrors and a Fresnel 
number of N = a 2 IXd = 1. The data are shown for various values of the parameter 

Figure 14-15 shows the transverse amplitude and phase distributions of the fundamental TEM 00 
mode. Figure 14-16 shows the amplitude and phase distributions of the TEM 01 mode. 



0.8 










0.6 








x*. x^ XV X. 


0.4 


- 






x. xp\\ 






TEM 00 
N = 


MODE 
1.0 


V ^^NVs 


0.2 








No v. 







1 i 


I I 


I I I 





=- ^"^^ 9 


= 












"575o 




- 








^ 


- 










- 








\^ 


- 










I 1 1 


1 1 1 


1 


1 


1 



0.2 0.4 0.6 0.8 1.0 

r/a 

Fig. 14-15. Relative field distributions ofthe TEMoo mode for 
a resonator with circular mirrors (N= 1). 



Diffraction Losses and Phase Shifts 

The diffraction loss of a resonator mode is defined as the fractional energy lost per transit due to 
diffraction effects at the mirrors. The phase shift fi is the phase shift suffered by the mode in transit 
from one mirror to the other, in addition to the geometrical phase shift, which is given by IndJX. The 
resonant frequency of a mode is given by 

v/v = (q + 1) + PM- 

The diffraction losses for the two lowest order (TEM 00 and TEM 01 ) modes of a stable resonator 
with a pair of identical, circular mirrors (a x = a 2 , g\ = g% = g) are given in Figures 14-17 and 14-18 
as functions of the Fresnel number N and for various values of g. The curves are obtained by a numerical 
solution of the resonator integral equations. Corresponding curves for the phase shifts are shown in 



14 Beams, Modes and Resonators 437 





Mnindwv 3Mivnab 



(saauoaa) asvHd aAiivnau 



438 



Handbook of Lasers 




0.1 0.2 0.4 0.6 1.0 



4 6 10 20 40 60 100 



N= a 2 /\d 



Fig. 14-18. Diffraction loss per transit (in decibels) for the 
TEMoi mode of a stable resonator with circular mirrors. 











gro 


















0.50 


40 














0.80 


20 




0.90 






0.95 






0.97 


^ 10 










55 e 


0.99 


& 4 










1 2 








\ro 


if) 
< 










0.6 


~ 


TEM 00 


MODE 




0.4 










0.2 










0.1 




! ::<■•■! 


— : 1 — ... ; 


Mil 1 1 ! 1 : : II 



0.1 0.2 0.4 0.6 1.0 2 4 6 10 20 40 60 100 

N= a2/\d 

Fig. 14-19. Phase shift per transit for the TEM 00 mode of a 
stable resonator with circular mirrors. 



14 Beams, Modes and Resonators 439 




40 60 100 



N = a 2 /Xd 

Fig. 14-20. Phase shift per transit for the TEM i mode of a 
stable resonator with circular mirrors. 

Figures 14-19 and 14-20. The horizontal portions of the phase shift curves can be calculated from the 
formula 

P = (2p + / + l)arc cos^/g 1 g 2 
= (2p + I + l)arc cos g, for g x =g 2 . 

It is to be noted that the loss curves are applicable to both positive and negative values of g, while the 
phase-shift curves are for positive g only; the phase shift for negative g is equal to 180 degrees minus 
that for positive g. 

Equivalent Resonator Systems 

BASIC RESONATOR PARAMETERS. Resonators of the kind shown in Figure 14-9 are charac- 
terized by three basic parameters, N, G x and G 2 , which are defined as 

N = a y a 2 \kd (Fresnel number) 

a 2 a 2 

G 2 =g 2 a -± = ^(l-d/R 2 ). 

If these three parameters are the same for any two resonators, then they have the same diffraction loss, 
the same resonant frequencies, and mode patterns that are scaled versions of each other. Equivalent 
resonators can be obtained by changing the curvature of the mirrors and at the same time their apertures. 

G-FACTOR REVERSAL. The diffraction loss and the intensity pattern of a resonator mode 
remain invariant if both g x and g 2 are reversed in sign; the eigenfunctions E and the eigenvalues y of the 
integral equations merely take on complex conjugate values. An example of such equivalent systems 
is that of plane-parallel (g x =g 2 = l) and concentric {g x = g 2 = - 1) resonator systems. 

RESONATOR WITH INTERNAL OPTICAL SYSTEM. A resonator with a general optical 
system of large aperture inserted between the mirrors has an equivalent resonator without the optical 
system in it. The basic parameters of this equivalent resonator are given by 



N = 



IB 



*-2("-& 



440 Handbook of Lasers 

where a x and a 2 are the radii of the mirror apertures, R x and R 2 are the radii of curvature of the mirrors, 
and A, B, C, and D are the ray matrix elements of the internal optical system. 

As an example, consider a resonator with an internal lens of focal length/ as shown in Figure 
14-21. If the lens aperture is large enough, this system is equivalent to a lensless resonator with the 
following basic parameters 



X {d 1 + d 2 - d -f)' 

G -lH-i;M-^)) 



where d x and d 2 are the distances between the lens and the mirrors. 




Fig. 14-21. Resonator with internal lens and the equivalent lensless 
resonator. 

A further example is the symmetric resonator with an internal limiting aperture in its central plane, 
as shown in Figure 14-22(a). The mirrors are assumed to be infinitely large. Such a resonator is equiva- 
lent to a Fabry-Perot resonator with a lens in its middle, as shown in Figure 14-22(b). The latter, by 
virtue of the example given above, has an equivalent as shown in Figure 14-22(c), with the basic para- 
meters given by 



N = 



-M) 



G 1 =G 2 = 1--. 
1 2 R 



14 Beams, Modes and Resonators 441 






( 


a) 






r—i ' 


T 

A 


d - 

2 


t- 


\- H 


i\ 




♦ 








f 


V 

R 
= 2 





(b) 



J/yi-d/2R / 



\ o/y, -d/ 



2R 



(C) 
Fig. 14-22. Resonator with internal aperture and equivalent resonators. 



Section 5 

Modulator, Nonlinear, 
and Raman Active Materials 



Page 

445 General Introduction to Modulator Materials 

447 Linear Electrooptic Materials 

460 Magnetooptic Materials 

478 Elastooptic Materials 

489 Non-Linear Optic Materials 

526 Stimulated Raman Scattering 



General Introduction to Modulator Materials 

Hans Jaffe 

Gould Laboratories 
Cleveland, Ohio 44108 

Control of optic path length from d.c. to microwave frequencies may be obtained by exposing the 
transmitting medium to electric field (Pockels effect), mechanical stress (elasto-optic effect), or magnetic 
field (Faraday effect). The three following sections deal with these effects. 

In principle these modulating effects may be regarded as second order effects in the superposed 
fields of the light wave and the applied control signal. In particular, the linear electro-optic (Pockels) 
coefficients r ik are of the same nature and symmetry as the 2nd order non-linear optic coefficients 
treated in Chapter 18. The numerical values are, however, substantially different for the non-linear 
coefficients (all fields at optic frequency) and the r ik (one field at optic, the other at low frequency). The 
changes in refractive index that can be achieved with practical levels of electric field or applied stress 
are at best of the order 10~ 3 . While this is marginal for steering of light beams by change of the de- 
flection angles of prisms, it is more than adequate for modulating the phase and hence by interference 
the intensity of visible or near infrared light, or of light diffraction from elastic waves. 

The electro-optic and elasto-optic coefficients show not much dependence on wavelength. The 
phase change for a given refractive index difference is, however, inversely proportional to wavelength. 
Hence substantial modulation becomes increasingly more difficult towards the farther infrared, even 
for the most favorable materials such as cadmium telluride. Similarly the intensity diffracted from an 
ultrasonic wave of given power is inversely proportional to light wavelength. 

Refractive index changes proportional to the square of an applied field are permitted by symmetry 
in all materials, but are significant only in strongly polar substances. On this is based the historic 
nitrobenzene Kerr cell, in which a birefrigence An = 2.13 • 10 ~ 8 • E 2 (in kV/cm) is induced by a field 
normal to the light beam. (At X = .59 n, slowly decreasing with increasing X (Ref. 1).) 

Recently much interest for modulators as well as optic data storage has developed for polycry- 
stalline ferroelectrics of the lead zirconate titanate family. The birefringence due to the quadratic 
electro-optic effect of a remanent polarization of 35 \i Coul/cm 2 is .01 1 in a typical composition (Ref. 2). 
The incremental linear electro-optic coefficient near remanence is r c = 610 • 10" 12 m/Volt, quite com- 
parable to the corresponding coefficients of single crystal ferroelectrics reported in the Tables. 

The only magneto-optic effect of sufficient magnitude for modulator devices is the Faraday effect, 
which is an equal increase and decrease in the refractive index of left and right circularly polarized light 
proportional to magnetic induction parallel to the light beam. It results in rotation of the azimuth of 
plane polarized light: 

0(radians) = 7r(» righ t - n u{ ^)l/X, 

where / is path length and X the wavelength in vacuum. At a given level of refractive index change the 
Faraday rotation is inversely proportional to wavelength, but the Tables show that this effect is over- 
shadowed by specific dispersion near absorption bands. For modulators in the longer wave infrared 
the Faraday effect of free carriers in semiconductors deserves consideration. For wavelengths below 
that corresponding to cyclotron resonance, this Faraday rotation increases proportional to X 2 (Ref. 3). 
For instance, 45° rotation of 10.6 \i radiation was obtained with 5300 gauss for a path of 0.5 mm in 
w-type InSb of carrier concentration 2 x 10 17 /cm 3 . Absorption losses were 10% (Ref. 4). 

445 



446 Handbook of Lasers 



REFERENCES 

1. "International Critical Tables VII," 109-111. 

2 " CW *"c. 8 Sta'l-1 f;?9 d 7l" HOt PreSSed (Pb ' ^^ Ti) ° 3 fem,electric ceramics for electro-optic applications," /. Am. 

3. S. D. Smith T. S. Moss, and K. W. Taylor, "The energy-dependence of electron mass in indium antimonide determined from 
measurements of the infrared Faraday effect," /. Phys. Chem. Solids, 11, 131-9 1959 <»"™omae determined trom 

1967. DemUS ' " 10 - 6 " Micron four -P°rt circulator using free carrier rotation in InSb," IEEE J. Quant. Electronics, QE-3, 416, 



Linear Electrooptical Materials 



Ivan P. Kaminow and Edward H. Turner 

Bell Telephone Laboratories, Incorporated 
Holmdel, New Jersey 07733 



DEFINITIONS 1 



(1) The linear electrooptic (or Pockets) effect refers to a change in relative optical dielectric im- 
permeability B u proportional to an applied electric field E k , whose highest frequencies are below the 
lattice resonances of a crystal. 

(2) The refractive index of a crystal is described by an ellipsoid (indicatrix) 

BijXiXj = 1 = B ll X 1 + B 2 2%2 + ^33^3 + 22?23^2^3 + ^-B^X^X^ + 2B l2 XiX 2 » 
in which summation over repeated indices is understood and B tJ = B Jt . By definition 



B ij = s dE i /dDj={^ i 



with e the vacuum permittivity and e the relative dielectric constant. 

(3) The electrooptic coefficient r ijk = r lk is defined by 

AB tJ = r ijtk E k 
&B t = r lk E k 

in which the indices i, j, k each cover the rectangular coordinate axes 1, 2, 3 and / = (ij) refers to the 
six reduced combinations 1 =(11), 2 = (22), 3 = (33), 4 = (23), 5 = (13), 6 = (12). 

(4) If r iJJk is determined at constant strain — for example, by making a measurement at high 
frequencies well above acoustic resonances of the sample — the crystal is clamped, as indicated by the 
letter (S) or r£ >fc . If r ij>k is determined at constant stress — for example, at low frequencies well below the 
acoustic resonances of the sample— the crystal is free, as indicated by the letter (T) or rJ JJk . Thus, 

r ij,k ~ r ij,k + Pij,r S dk,rs 

in which p u „ and d k>rs are elastooptic and piezoelectric coefficients, respectively. 

(5) The linear electrooptic effect occurs only in acentric crystals. The form of the electrooptic 
tensor is determined by the point group symmetry of the crystal. Only the 21 acentric groups (those 
lacking a center of inversion) may have non-vanishing coefficients. Their reduced matrix forms are 
summarized in Table 15-1. 

(6) A nonlinear susceptibility x ijk can be defined 2 by 

Pi = £o XijkEj Sk- 
in a principal axis system where B tj = for i #y, and B u = B t = 1/e, 

ABij= -ASij/SiBj, 
for Ae y ^ e t , 8j . Then 

r iLk =-2B i B j Xij, k {-<0',<o,Q) 

447 



448 Handbook of Lasers 

and 



or 



r iJ>k = -4B t Bjd kJ Jp; co, -co) 



r lk = -^BiBjd^O; co, -co) 



in which d kl (0;co, -co) is the optical rectification coefficient for optical frequency co, and the arguments 
in parenthesis represent the frequencies of the (i,j, k) fields, respectively. 

(7) If an electrooptic coefficient is defined in terms of polarization as suggested by Pockels, 3 
rather than electric field, the resulting coefficient 



Jij,k 



r ij,k 



e O 0* ~ 1) 



varies over a much narrower range, for a variety of crystals, than r IM . The Miller delta 4 is a similar 
coefficient 



X _ %ij,k 

°ij,k — 



2( Ei - l)(sj - l)(e k - 1) 

£j &j ^"ij,k 

= 4( £i - l)(e 7 . - l)( £jt - 1) 

with e,. and e,- optical dielectric constants and e* the dielectric constant at the modulating frequency. 

(8) If the principal refractive indices are n\ = e a , in the presence of an applied electric field E p , 
then 



— -Mj)=-(t)-^ 



for Ae a <^ e a . For applications of the electrooptic effect to modulation of light, a. figure of merit F may 
be defined for a particular substance by 5 



f _"^ = /2£o\/ l\ 2 A/ \ 



where e p is the dielectric constant at the modulating frequency, X is the optical wavelength, A/ is the 
modulating bandwidth, P is the modulating power, and rj a is the phase modulation index. 

(9) The half-wave voltage of an electrooptic crystal, [E k • /] A/2 , is the product of applied electric 
field strength, E k , and propagation distance, /, required to produce a phase difference of n between 
orthogonal polarizations, i.e., a half-wave retardation. In the case of uniaxial crystals in which the 
optic axis is the z (or 3) axis, and the propagation direction is normal to this axis, 



[^3 *Ja/2 — ~3 3 — = -5 — 

nir 33 -nir 13 n%r c 



Here, r c = r 33 - («?/n|)r 13 . 



TABLES OF COEFFICIENTS 

The tables are divided according to the general structure of the electrooptic materials. Table 15-2 
contains isomorphs of ferroelectric KH 2 P0 4 and antiferroelectric NH 4 H 4 P0 4 . Table 15-3 contains 
AB0 3 -type crystals, which are ferroelectric or pyroelectric. Table 15-4 contains tetrahedrally coor- 
dinated binary AB compounds, which are semiconductors. Table 15-5 contains the remaining mis- 
cellaneous materials that do not fit the previous categories. 

We have attempted to select the most recent and reliable data; however, the reader should consult 
the original work to determine its reliability. Typical accuracies for r lk are ± 15 %. References containing 



15 Linear Electrooptical Materials 449 

more extensive wavelength and temperature dependence are indicated by X and t, respectively. Electro- 
optic coefficients are stated in MKS units (m/volt); to convert to CGS units (cm/stat volt), multiply 
by 3 x 10 4 . Unless stated explicitly, the signs of r lk have not been determined. 

As a rule, r lk has little optical wavelength dependence in the transparent region of a crystal, and 
little modulating frequency dependence below infrared lattice mode resonances and above dimen- 
sional acoustic mode resonances. In ferroelectrics and other materials exhibiting a phase transition, 
the electrooptic coefficients may depend strongly on temperature and generally increase approximately 
in proportion to (e - 1) as the transition temperature, T c , is neared. For the most part, electrooptic 
coefficients are quoted for room temperature. 



TABLE 15-1. ELECTROOPTIC MATRICES 



&B 22 
Afi 3 3 
Afl 23 

LBt. 



\&B 12 J \ 



TRICLINIC -1-d 

Iru r 12 r 13 \ 

^21 ^22 *23 

^31 ^32 r 33 

^41 f*2 ^43 

fsi r S2 ^53 

f~61 ^62 ^63 J 



(18) elements 



/o 





Ui 



r S i 



r 2 i 

/*22 

r 2 3 


r S 2 










^43 


r 6 3 



MONOCLINIC 



(2\\X 2 ) 



(8) 




(m±X 2 ) 



°l do) 



ORTHORHOMBIC 

222 — D 2 mm2 — C 2 



/o 




r 4 i 



, r 52 
\0 










(3) 







o n 2 







r 13 ' 
r 23 




r 33 






(5) 



TETRAGONAL 



4-C* 





















f41 


r S i 


r S i 


—r*i 









r i3 \ 

ris 

r 3 3 





°/ 



(4) 



/o 




r 51 
\° 







r S i 





^13^ 

— ri3 







r 6 3J 



/° 










(4) \° 



422 - D A 






-/41 





o\ 





°/ 



(1) 



4mm — C* v 



\° 



r sl 
r 5 i 







r%3 



r 33 





V 



42m - D 2d 




(2\\X t ) 



(2) 



450 



Handbook of Lasers 



TABLE 15-1. ELECTROOPTIC MATRICES (Continued) 



-rxi 


>41 

—r 2 2 



3-C 3 

— J*22 
/*22 


r S i 



^3 3 






TRIGONAL 





>41 

°/ (6) \ ° 



32 -D 3 






— >41 

— fll 



o\ 





°/ 



3m 



(2) 






— ^22 


rn\ 





/*22 


ris 








^33 





''si 





rsi 





o . 


f~22 





0/ 



(4) 



/o 




>41 

\° 



6-C 6 





r S i 





r i3 

^33 




HEXAGONAL 



ru —r 22 0\ 

-fn >22 







(4) \—r 2 2 —ru 0J 








(2) \° 



622 - D 6 





—r*i 




»\ 








°1 



(1) 



6mm — C 6v 



6m2 - D 3h 



/o 





\° 







r S i 





fl3\ 

ris 

7*33 





°) 0) \ 








-r 2 2 



f"22 
A*22 








o\ 







0n-L*l) 



(1) 



CUBIC 



432-0 




25 and 43m - T and T d 


/o o o\ / \ 



























A-41 









r 41 




\0 


(0) 


\ r A1 


0) 



15 Linear Electrooptical Materials 

TABLE 15-2. KDP- AND ADP-TYPE CRYSTALS 

42m ABOVE T P 



451 





T c 

(°K) 

[6] 


Electrooptic coefficients 


Refractive index 


Dielectric const. 




r 63 (lO- 12 m/V) 


r 41 (10- 12 m/K) 


"3 


"i 


e 3 


d 


KH 2 P0 4 (KDP) 


123 


(r)-10.5[7];[8,A];[9,f] 
(T)9.37[10] 


+ 8.6[7] 


1.47 


1.51[13,14;A,f] 


(7/)21 


42[15] 






(5)8.8[16]; f8,A] 
(5)8.15[17];r 63 <0[ll] 


r 41 <0[12] 






(5)21 


44[18] 


KD 2 P0 4 (DKDP) 


222 


(r)26.4H9][8,A][9,/] 
(5)24.0[20]; .93rh [8,A] 


8.8[21] 


1.47 


1.51 [14 A'] 


(D50[19] 
(5)48 


58[22] 


KH 2 As0 4 (KDA) 


97 


(r)10.9 


12.5[21] 


1.52 


1.57[21] 


(7)21 
(5)19 


54[15] 
53[22] 


KD 2 As0 4 (DKDA) 


162 


(D18.2[23,A] 






1.56[23] 






RbH 2 P0 4 (RDP) 


147 


(D15.5[23,A] 
(S).91 rh [8,A] 






1.51 [23] 






RbH 2 As0 4 (PvDA) 


110 


(r)13.0[21] 




1.52 


1.56[21] 


(7027 
(5)24 


41 [24] 
39[24] 


RbD 2 As0 4 (DRDA) 


178 


(D21.4[23,A] 






1.56[23] 






CsH 2 As0 4 (CDA) 


143 


(D18.6[23,A] 






1.57[23] 






CsD 2 As0 4 (DCDA) 




(D36.6[23,A] 






1.57[23] 






NH 4 H 2 P0 4 (ADP) 


148* 


(D -8.5[7], [25], [8,A] 
(S)5.5[7],4.1[27],[8,A] 


24.5[21],23.1[26] 
r 41 < 0[12] 


1.48 


1.53[13,14;A,f] 


CT)15 
(5)14 


56[15] 
58[22] 


ND 4 D 2 P0 4 (DADP) 


242* 


(D11.9[23,A], [28,f] 






1.52[23] 






NH 4 H 2 AsQ 4 (ADA) 




(r)9.2[23,A] 






1.58[23] 







* Antiferroelectric transition. 



452 Handbook of Lasers 

TABLE 15-3. ABO3-TYPE COMPOUNDS 



Material and Symmetry 


Electrooptic coefficients 






Refractive index 


Dielectric const. 
















(critical temp., °K) 


r l3 (lO- 12 m/V) 


r lk (10- 12 m/K) 


A(ju,»i) 




fit 


\(fim) 


£i 


LiNb0 3 , 3m 


(T)r c =19 


(r>22 = 7 


.633[29] 


"i 


= « 2 = 2.3780 


.45(38,A] 


(T) £l = e 2 = 78(37,/ 


(1470) 


(7> c =17.4 


(7>22 = 3.2 


.633[30] 




2.2716 


.70[39,/,A] 


(T)e 3 = 32 






(7> 51 = 32 






2.2370 


1. 00(41, /,A] 


(5^=62 = 43(61] 




(7> 33 =+32.2 


( r> 22 = 6.8 


.633[31,/] 




2.1974 


2.00 


(S)e 3 = 28 




(7> 13 = +io 








2.1155 


4.00 






(T)r c =18 


(7> 22 = 6.7 


.633[34] 




« 3 = 2.2772 


.45 






(T)r c =17 


(T)r 22 = 5.7 


1.15[34] 




2.1874 


.70 






(7>c =16 


(7> 22 = 3.1 


3.39[34] 




2.1567 


1.00 






All(r> (J >0 




.633[32] 




2.1250 


2.00 






(S)r 33 = 


(,S)r 22 = 3.4 


.633[35] 




2.0553 


4.00 






+30.8 
















(5)r 13 = +8.6 


(S>5i = +28 














CS> 33 = 28 


(S)r 22 = 3.1 


3.39[36] 












(S)r 13 = 6.5 


(S)r sl = 23 












LiTa0 3 , 3m 


(7> c =22 




.633[40] 


«i 


= w 2 = 2.1834 


.60[42,A] 


(7>2 = £l = 51(43] 


(890) 


(5)r 33 = 30.3 


(S)r 51 = 20 


.633(40] 




2.1305 


1.20 


(7> 3 = 45 




(S)r 13 = 7 


(S)r 22 & 1 






2.0335 


4.00 


(S)e 2 = ei = 41 




GS>3 3 = 27 


(S)r 5l = 15 


3.39(36] 




n 3 = 2.1878 


.60 


GS)e 3 = 43 




CS> 13 =4.5 


(JS)r 22 «» .3 






2.1341 


1.20 






All (7>„ > 




.633(33] 




2.0377 


4.00 




BaTi0 3 , 4mm 


(7> c =108 


(7> 51 = 1640 


.546(44,/] 


"i 


= n 2 = 2.46 


.546[47A] 


(7> x = e 2 = 3600 


(395) 














[47/] 




(S> c =23 


(£>5i = 820 


.546(45,/] 




n 3 = 2.40 




(De 3 = l 35(48 ;47/] 




(S)r e =19 




.633(46] 


«i 


= « 2 =2.41 


.633[47A] 


(5)6! = e 2 = 2300 
[47/] 




(5>3 3 = 28 








n 3 = 2.36 




(S)e 2 = 60(48; 47/] 




(S)r 13 = 8 














K3Li 2 Nb 5 Oi5, 4mm 


(7> 33 = 78 




.633(49] 


«i = 


= n 2 = 2.277 


.633(49] 


(7>! = e 2 = 309(49] 


(693) 


(7> 13 = 8.9 








« 3 = 2.163 




(7> 3 = 100(49] 


Sr.75Ba.25Nb 2 6 , 4mm 


(7> c =1410 




.633(50] 


"i 


= « 2 = 2.3117 


.633(50] 


e 3 = 3400(50] 


(~330) 


(7> 33 = 1340 
(7> 13 = 67 
(S)r c =1090 


(7> 51 = 42 






n 3 = 2.2987 




(15MHz) 


Sr. 5 Ba. 5 Nb20 6 , 4mm 


(7> c =218 
(15MHz)r c 
= 96 




.633(50] 


"i : 


= « 2 = 2.3123 
n 3 = 2.2734 


.633(50] 


£ 3 = 450(50] 
(15MHz) 


Sr 25Ba.7sNb 2 06, 4mm 






.633(50] 


"i 


= n 2 = 2.3144 


.633(50] 


£3 = 118(50] 


(-520) 


(15MHz)r c 

= 45 












(15MHz) 


KTa,Nbi_ x 3 ,¥/M/n 


(7> c =450 


(T)r 51 = +50 


.633(51,/] 


"i = 


= « 2 = 2.318 


.633(51,/] 




(-330) 










n 3 = 2.277 






PbTi0 3 , 4mm 


(5)r 33 = 5.9 




.633(52] 


«i = 


= n 2 = 2.668 


.633(52] 


GS)e 3 = 31(52] 


(765) 


(S)r 13 = 13.8 








n 3 = 2.659 






KSr 2 Nb 5 15 , 4mm 


(7> c =130 




.633(53,/] 


n — 


2.25 


.633(53] 


(r)£ 3 = 1000(53,/] 


(433) or 4 














(r)£ x = 1200 


LiI0 3 , 6 


CS> 33 = +6.4 


(,S> 41 = 1.4 


.633(54] 


«i : 


= n 2 = 1.881 


.633(55,A] 


(T)e 3 = 554(54,/] 


(Pyroel.) 


(S)r 13 = +4.1 


GS>si = 

+3.3 






« 3 = 1.736 




(T) £l = 65 

(5)£ 3 = 6.5(56] 
(S) £l = 8(57] 


Ba 2 NaNb s Oi5, mm2 


(T)r c =34 




.633(59,/] 




«i = 2.322 


.633[58,A] 


(T)£i = 235(60] 


(833) 


(7> 33 =48 


(r>42 = 92 


.633(58] 




n 2 = 2.321 




(7> 2 = 247 




(7> 13 = 15 


(7> 51 = 90 






n 3 = 2.218 




(T)e 3 = 51 




(7> 23 = 13 












(5)£i = 222 




(S)r 33 = +29 


(5)r 42 = 75 


.633(52] 








(S)e 2 = 227 




(S)r 23 = 8 


(S)r sl = 88 










(5)£ 3 = 32 




(5> 13 = 7 















15 Linear Electrooptical Materials 453 
TABLE 15-4. AB-TYPE COMPOUNDS 





Sym 


Electrooptic coefficients 


Refractive index 


Dielectric const. 


Material 


r lk (lO- 12 m/v) 


X(jim) 


n, 


A(/xm) 


£i 


GaAs 


43m 


(S)r 41 = 1.2 


.9 to 
1.08[63] 
3.39[64] 


n = 3.60 


.9[70] 


(5)e = 13.2[72] 






(S)r 41 = -1.5 


n = 3.50 


1.02[70] 


(5)£ = 12.3[73] 






(S+7> 41 = 1.2 


1.0 to 


n = 3.42 


1.25 [70] 


(De=12.5[71] 






to 1.6 


3.0[65] 












(7> 41 = 1.0 


4.0 to 


« = 3.30 


>5.0[71] 








to 1.2 


12.0[65] 












(7> 41 = 1.6 


10.6[66,67] 












(£)r 41 = 1.5 


Raman Scat. 
68,69 








GaP 


43m 


(5)r 41 = -1.07 


.56 to 


n = 3.4522 


.545[74] 


(5)e = 12[76] 






to -.97 


3.39[74] 


to 3.2462 

n = 3.2422 

to 3.01 37 


to .7 
•7[74] 
to 4.0 


(5)e = 10[77] 


ZnTe 


43m 


(7> 41 = 4.45 


.59[78,A] 


n = 3.1 


.57[78,A] 


(7>=10.1[82] 






to 3.95 


.69[78,A] 


2.91 


.7[78,A] 


(5)e=10.1[82] 






(7> 41 = 1.4 


10.6[67] 


2.76 


1.24[79] 








(5)r 4x (rel.) 


5.8 to 
6.9[81,A] 


2.71 


2.06[79] 








(S)r 41 = 4.3 


.633[84] 


2.70 


10.6[80] 








(5)r 41 = 3.2 


3.39[84] 








ZnSe 


43m 


(7> 41 = 2.0 
(5)r 41 = 2.0 


.546[85] 
.633[84] 


«o = 2.66 


.546[79] 


(r)e = 9.1[82] 
(5)e = 9.1[82] 






(7> 41 = 2.2 


10.6[88] 


n = 2.3 


10.6[88] 




ZnS 


43m 


(7> 41 = 1.2 


.4[86,A] 


wo = 2.471 


.45[75] 


(De=16[87] 






(7> 41 = 2.1 


.65[86,A] 


2.364 


•6[75] 


(S)e = 12.5[87] 






(5)r 41 = 1.6 , 


.633[84] 


2.315 


.8[75] 


(r,5)e = 8.3[82] 






(£)r 41 = 1.4 


3.39[84] 


2.260 


2.4[75] 




ZnS 


6mm 


(S)r 33 = 1.8 


.633[84] 


n 3 = 2.709 


.36[89] 


(r) £l = £ 3 = 8.7[96] 






(5)r 33 = 1.7 


3.39[84] 


"i = «2 = 2.705 


.36[89] 


(5)e! = 8.7 






(S)r l3 = .9 


.633[84] 


« 3 = 2.368 

«! =n 2 = 2.363 


.6[89] 
.6[89] 




ZnO 


6mm 


(S)r 33 = +2.6 


.633[84] 


« 3 = 2.123 


.45[75] 


(5)6! = e 2 = 8.15[90] 

xe 3 






(S)r 13 = -1.4 


.633[84] 


«! = n 2 = 2.106 


.45[75] 






(5)r 33 =+1.9 


3.39[84] 


n 3 = 2.015 


.6[75] 








(5)r 13 = + .96 


3.39[84] 


«i ="2 = 1999 

n 3 = 1.9068 

Hl =„ 2 = 1.8891 


•6[75] 
4.0[75] 
4.0[75] 




CdTe 


43m 


(7> 41 = 6.8 


3.39[91] 


n = 2.82 


1.3[79] 








(7> 41 = 6.8 


10.6[91] 


«o = 2.60 


10.6[93] 


GS)e = 9.4[73] 






(7> 41 = 5.5 


23.35[92] 


n Q = 2.58 


23.34[93] 








(7> 41 = 5.0 


27.95[92] 


/to = 2.53 


27.95[93] 




CdSe 


6mm 


(S)r 33 = 4.3 


3.39[84] 


n 3 = 2.542 


1.15[75] 


(7> 3 = 10.65[82] 






(S)r 13 = 1.8 


3.39[84] 


«! = « 2 = 2.522 

n 3 = 2.471 

"i = n 2 = 2.452 


1.15[75] 
3.39[75] 
3.39[75] 


(Dd = 9.70[82] 
(5)e! = 9.33[82] 
(5)e 3 = 10.20[82] 


CdS 


6mm 


(7> c =4 


.589[94] 


n 3 = 2.48 


.63[80] 


(T)e 3 = 10.33[82] 






(7> 51 = 3.7 


.589[94] 


"i = «2 = 2.46 


.63[80] 


(T)sx = 9.35[82] 






(7> c =5.5 


10.6[67] 


n 3 = 2.3 


10.0[80] 


(5)e x = 9.02[82], 
8.7[83] 






(5)r 33 = 2.4 


.633[84] 






(S)e 3 = 9.53[82], 
9.25[83] 






(S)r 13 = 1.1 


.633[84] 









454 



Handbook of Lasers 



TABLE 15-4. AB-TYPE COMPOUNDS (Continued) 





Sym 


Electrooptic coefficients 


Refractive index 


Dielectric const. 


Material 


r lk (lO- 12 m/V) 


X(fxm) 


itt 


X(/j,m) 


St 


CuBr 


43m 


(7> 41 = .85 


.525[95] 


n = 2.16 
n = 2.09 


.535 [96] 
.656[96] 




CuCI 


43m 


(7>4i = 3.6 

(7> 41 = 3.2 
(5> 41 = +2.35 
(SKi = +2.20 


.633[97] 
10.6[97] 

.633 [84] 
3.39[84] 


n = 2.02 
«o = 1.958 
n = 1.91 
n =1.90 


.5[98] 
.633[98] 
3.39[98] 
10.0[98] 


(5)£ = 7.5[99] 


HgS 


32 


(5)r 11 =3.1 
(5)r 41 = 1.4 
(S)r 1± = 4.2 
(5> 41 = 2.4 


.633[100] 
.633[100] 
3.39[100] 
3.39[100] 


n 3 = 3.232 

"i = n 2 = 2.885 

n 3 = 2.900 

"i = n 3 = 2.637 


.633[101] 
.633[101] 
3.39[101] 
3.39[101] 





TABLE 15-5. MISCELLANEOUS CRYSTALS 





Sym 


Electrooptic constants 


Refractive index 


Material 


r lk (10- 12 n 


t/V) 


A(/iw) 


ni 


XQjLm) 


Bi4(Ge04>3 


43m 


(7> 41 = 1.03 




.45 to .62[102] 


n = 2.07 


[102] 


(CH 2 ) 6 N 4 :(HMT- 
hexamethylenetet- 
ramine) 


43m 


(7> 41 = 0.71 - 
(7> 41 = 0.78 
(5)r 41 < 0.14 


0.8 


.546[103] 
.633[105] 
.633[105] 


n = 1.591 
n = 1.594 


.589[104] 
.633[105] 


Hauynite (mineral) 


43m 


(7> 41 < .04 




[106] 


n = 1.496 




Langbeinites: 
K 2 Mg2(S0 4 )3 
(NH 4 )2Cd 2 (S04) 3 
(NH 4 )2Mn 2 (S04) 3 
Tl 2 Cd2(S0 4 )3 
K 2 Mn 2 (S04)3 


23 
23 
23 
23 
23 


(7>4i = 0.40 
(7>4i = 0.70 
(7> 41 = 0.53 
(7> 41 = 0.37 
(7> 41 = 2.0 




.546[107] 
.546[107] 
.546[107] 
.546[107] 
.453 to .642[108] 


n = 1.535 
n = 1.606 
n =1.57 
n = 1.730 
1.62 


.589[107] 
.589[107] 
.589[107] 
.589[107] 
.45 to .65 


Rb 2 Mn 2 (S04) 3 


23 


(7>4! = 1.9 




.453 to .642[108] 


1.60 


[108] 
.45 to .65 


Tl 2 Mn 2 (S0 4 )3 


23 


(7> 41 = 2.1 




.453 to .642[108] 


1.80 


[108] 
.45 to .65 


K 2 Ni 2 (S0 4 )3 


23 


(r> 41 = 1.0 




.453 to .642[108] 


1.70 


[108] 

.45 to .65 

[108] 


NaC10 3 


23 


(7> 41 = .4 




.589[109] 


n = 1.515 


[110] 


Na 3 SbS 4 -9H 2 


23 


vT)n?r 4 i = 5.66 
(r)n?r4i = 5.62 




.42[111] 
1.08[111] 






Sodium uranyl 
acetate 


23 


(7> 41 = .87 




.546[112] 


n = 1.507 


.546[112] 


LiKS0 4 


6 


(T)r c - 1.6 




.546[113] 


n 3 xn l = n 2 = 1.474 


.546[113] 


LiNaS0 4 


3m 


(T)r 22 < .02 




.546[113] 


|«3 = 1.495 
U 1 =n 2 = 1.490 


[110] 



15 Linear Electrooptical Materials 
TABLE 15-5. MISCELLANEOUS CRYSTALS (Continued) 



455 





Sym 


Electrooptic constants 


Refractive index 


Material 


r lk (lO- 12 m/V) 


A(/i/w) 


n t 


A(/im) 


Tourmaline 


3m 


(T)r 22 = 0.3 


.589[109] 


r« 3 = i.65 


[110] 






CS>33 = r 13 = 1.7 


.633[129] 


l«! = « 2 = 1.63 




Na 3 Li(Cr0 4 ) 2 -6H 2 


3m 


(7> 22 = 0.92 


.50[134] 


«i =n 2 = 1.643 


.50[134] 






(T)r 22 = 0.82 


.52[134] 


«! = « 2 = 1.635 


.52[134] 






(7> 22 = 0.77 


.60[134] 


"1 =« 2 = 1612 


.60[134] 


Ag 3 AsS 3 (Proustite) 


3m 


CS)(«i/-i3-"ir 3 3) = 70 


.633[114] 


«x = 3.02 


.633[114] 






(S)n\r 22 = 29 


.633[114] 


n 3 = 2.74 


.633[114] 




NOTE: 


Transparent 0.6 to 13 /im; 


Si. x e 3 = 20; p = 


= 10 5 Ocm[114]. 




K.2S2O6 


32 


(7> 11 =0.26 


.546[113] 


(n 3 = 1.1518 
l«! =« 2 = 1.456 


[110] 
[113] 


Cs 2 C 4 H 4 6 


32 


(T)r tl = 1.0 


.546[113] 


|«3 = 1.546 

l/ij =n 2 = 1.564 


[113] 


SrS 2 5 -4H 2 


32 


(0^=0.1 


.546[113] 


|«3 = 1.528 

in, =« 2 = 1.532 


[110] 










[110] 


Se 


32 


(S)n 3 iril =89 


1.15[115] 


«! = 2.737, 
n 3 = 3.573 


1.15[116,A] 






(5K, -2.5 


10.6[117] 


«x = 2.64, 
« 3 = 3.41 


10.6[116,A] 




NOTE: Absorption-edge ~ 


8/u,m [11 8,A], e^ 


= 8 [119]. 




SiQ 2 (Quartz) 


32 


(T) ril = -0.47 


.409 to .605[109], n 3 = 1.555 


.546[109] 








[120A] 










(7> 41 = 0.20 


[109] 


"1 ="2 = 1.546 


.546[109] 



(S)r t t = 0.23 (calculated) [121 ] 

(5)r 11= 0.29 .633[122] 

(5)r lt =0.174 .633[123] 

NOTE: r lt < and r 41 > in left-handed quartz [123]. 



(C 6 H 12 6 ) 2 NaBrH 2 


32 


{T)r lt =QA 


.546[113] 


n 3 = 1.560 


.546[113] 


AgGaS 2 


42m 


(7> 63 = 3.0 
(7> 41 = 4.0 

NOTE: (S)e 3 


.633[130] 
= 14, OSK = 10[130]. 


n 1 =n 2 = 2.55 
« 3 = 2.50 


.633[131,A] 


Gd 2 (Mo0 4 ) 3 


42m 


(T)nfr 63 = 17 (450°K) .633[125f] 


«i =« 2 = 1-528 






(450°K) 






n t xn 2 = 1.848 


.633[125] 




mm2 


(T)nfr 13 - nlr 33 = 


17.5 .633[125r] 


« 3 = 1.901 


.633[125] 




(300°K) 


(300°K) 
NOTE: T c = 


= 432°K, e 3 = 8 [125?]. 






CdGa 2 S 4 


4 


(7> 13 = 0.37 

r 63 = 3.5 


.50[135]1 
.50[135]i 


«i = «2 = 2.3 


.50[135] 


(NH 4 )2C 2 4 H 2 


222 


(7> 41 = 230 
(7> 52 = 330 


.633[136] 


«! = 1.437 
« 2 = 1.547 


.65[138] 



456 Handbook of Lasers 

TABLE 15-5. MISCELLANEOUS CRYSTALS (Continued) 



Electrooptics coefficients 



Refractive index 



Material 



Sym 



r lk (lO- 12 m/V) 



A(jLtm) 



«i 



A(/x/w) 



(7> 63 = 250 
(T)r <4 250 

(S>63 » 2 



n 3 = 1.590 



.633[137] 
.633[129] 



Rochelle Salt 

NaN0 2 



222 See Ref. [120] 

mm2 (J)r 22 - 1 ^ I r 32 = 4.1 .546[126/] 
(7> 32 -|-| r 12 = 4.2 



(T)r 2 . 






»i = 1.347 
« 2 = 1.415 
« 3 = 1.661 



.546[126] 



(7> 43 =-1.9 
(7> 61 = -3.0 

NOTE: Author takes X 2 as polar axis. Transition to mmm at 423°K, [126]; (S)ei = 5, e 2 = 4, £ 3 = 8 [132*]. 



Triglycine sulfate 
(TGS) and deuter- 
ated triglycine 
sulfate (DTGS) 


2 


see Ref. [120] 
NOTE: (S) s, see 
[132,/]. 








C(CH 2 OH) 4 


2 


(7> 52 = 1.45 
(r)|r ia -r 32 | = 0.7 


.46to.70[127] 
.46 to .70[127] 


«x = 1.528 
« 2 x « 3 = 1.56 


[109] 


Ca 2 Nb 2 7 


2 


CO 


nl 

^22 — Z5 r 12 

n 2 


= 12 


.63[128] 


«i = 1.97 


[128] 






CO 


nl 

''22 — r3 r 32 
"2 


= 14 


.63[128] 


n 2 = 2.16 


[128] 






(S) 


^22 — l3'"32 

n 2 


= 13 


.63[128] 


n 3 = 2.17 


[128] 






(S)r 12 = 6.7 
(S)r 22 = 25.5 
(S)r 32 = 6.4 
(5> 41 = 2.7 
(S)r S2 < 0.6 
(S)r 63 = 0.9 


.63[133] 












E 


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458 Handbook of Lasers 

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Electronics, QE-4, 23, 1968. 

68. A. Mooradian and A. L. McWhorter, " Light scattering from plasmons and phonons in GaAs," p. 297 in " Light scattering 
spectra of solids," G. B. Wright, ed. Springer, New York, 1969. 

69. W. D. Johnston, Jr., and I. P. Kaminow, "Contributions to optical nonlinearity in GaAs as determined from Raman scat- 
tering efficiencies," Phys. Rev., 188, 1209, 1969. 

70. D. T. F. Marple, " Refractive index of GaAs," /. Appl. Phys., 35, 1241, 1964. 

71. K. G. Hambleton, C. Hilsum and B. R. Holeman, "Determination of the effective ionic charge of gallium arsenide from 
direct measurements of the dielectric constant," Proc. Phys. Soc, 77, 1147, 1961. 

72. S. Jones and Shing Mao, " Further investigation of the dielectric constant of gallium arsenide," /. Appl. Phys., 39, 4038, 1968. 

73. C. J. Johnson, G. H. Sherman and R. Weil, " Far infrared measurement of the dielectric properties of GaAs and CdTe at 
300K and 8K," Appl. Optics, 8, 1667, 1969. 

74. D. F. Nelson and E. H. Turner, " Electrooptic and piezoelectric coefficients and refractive index of gallium phosphide," 
/. Appl. Phys., 39, 3337, 1968. 

75. W. L. Bond, " Measurement of the refractive indices of several crystals," /. Appl. Phys., 36, 1674, 1965. 

76. I. P. Kaminow and E. H. Turner, "Electrooptic light modulators," Proc. IEEE, 54, 1374, 1966. 

77. C. Hilsum and A. C. Rose-Innes, "Semiconducting III-V Compounds," New York, Pergamon, 1961. 

78. T. R. Sliker and J. M. Jost, "Linear electrooptic effect and refractive indices of cubic ZnTe," /. Opt. Soc. Am., 56, 130, 
1966. 

79. D. T. F. Marple, " Refractive index of ZnSe, ZnTe, and CdTe," /. Appl. Phys., 35, No. 3 (Part 1), 1964. 

80. L. R. Shiozawa and J. M. Jost, " Research on II-VI compound semiconductors," Clevite Corporation, Palo Alto, California, 
Report AD 620297, May 1965. 

81. H. Pursey, P. A. Page and M. J. P. Musgrave, " On the dispersion of optical and electrooptical coefficients in zinc telluride," 
/. Phys. C. (Solid State Physics) 2, 1085, 1969. 

82. Don Berlincourt, Hans Jaffe and L. R. Shiozawa, " Electroelastic properties of the sulfides, selenides and tellurides of zinc 
and cadmium," Phys. Rev., 129, 1009, 1963. 

83. A. S. Barker, Jr., and C. J. Summers, "Infrared dielectric function of CdS," /. Appl. Phys. 41, 3552-3554, 1970. 

84. E. H. Turner, to be published. 

85. R. W. McQuaid, "Electrooptic properties of zinc selenide," Proc. IRE (correspondence), 50, 2484, 1962; and "Correction 
to 'Electrooptic properties of zinc selenide,'" Proc. IEEE, 51, 470, 1963. 

86. S. Namba, " Electrooptical effect of zincblende," /. Opt. Soc. Am., 51, 76, 1961. 

87. S. J. Czyzak, D. C. Reynolds et al, "On the properties of single cubic zinc sulfide crystals," /. Opt. Soc. Am., 44, 864, 
1954. 

88. C. Kojima, T. Shikama, S. Kuninobu, A. Kawabata and T. Tanaka, "The electrooptic effect in cubic ZnSe at 10.6/a," 
Jap. J. Appl. Phys., 8, 1361, 1969. 

89. T. M. Bieniewski and S. J. Czyzak, "Refractive indexes of single hexagonal ZnS and CdS crystals," /. Opt. Soc. Am., 53, 
496, 1963. 

90. R. J. Collins and D. A. Kleinman, "Infrared reflectivity of zinc oxide," /. Phys. Chem. Solids, II, 190, 1959. 

91. James E. Kiefer and Amnon Yariv, "Electrooptic characteristics of CdTe at 3.39 and 10.6/x," Appl. Phys. Lett., 15, (1), 
26, 1969. 

92. C. J. Johnson, "Electrooptic effect in CdTe at 23.35 and 27.95 microns," Proc. IEEE, 56, 1719, 1968. 

93. O. G. Lorimer and W. G. Spitzer, "Infrared refractive index and absorption of InAs and absorption of InAs and CdTe," 
/. Appl. Phys., 36, 1841, 1965. 

94. D. J. A Gainon, " Linear electrooptic effect in CdS," J. Opt. Soc. Am., 54, 270, 1964. 

95. L. M. Belyaev, G. F. Dobrzhanskii, Yu. U. Shaldin, "Electrooptical properties of copper chloride and bromide crystals," 
Sov. Phys.-Solid State, 6, 2988, 1965. 

96. Landolt-Bornstein, "Zahlenwerte and Funktionen," II Band, 8 Teil, Optische Konstanten. 

97. T. Sueta, T. Matsushima, T. Nishimoto and T. Makimoto, "Modulation of 10.6 micron laser radiation by CuCl," Proc. 
IEEE, 58, 1378, Sept. 1970. 

98. Albert Feldman and Deane Horowitz, "Refractive index of cuprous chloride," /. Opt. Soc. Am., 59, 1406, 1969. 

99. P. Alonas, G. Sherman, C. Wittig and P. D. Coleman, " Dielectric properties of CuCl at 300K in the 3-30/u. region," Appl. 
Optics, 8, 2557, 1968. 

100. E. H. Turner, " Linear electrooptic effect in HgS (cinnabar) at .63 and 3.39 microns," IEEE, J. Quant. Electronics, QE-3, 
695, 1967. 

101 . W. L. Bond, G. D. Boyd and H. L. Carter, Jr., " Refractive indices of HgS (cinnabar) between .62 and 1 1ft," /. Appl. Phys., 
38, 4090, 1967. 

102. R. Nitsche, " Crystal growth and electrooptic effect of bismuth germanate, Bi4.(Ge0 4 ) 3 ," /• Appl. Phys., 36, 2358-2360, 1965. 

103. R. W. Lee, " Linear electro-optic (Pockels) effect in hexamethylenetetramine : Influence of crystal strain," J. Opt. Soc. Am., 
59, 1574-1580, 1969. 

104. G. H. Heilmeier, " The dielectric and electrooptic properties of a molecular crystal-hexamine," Appl. Opt., 3, 1281-1287, 1964. 

105. K. F. Rodgers, "The Pockels effect in hexamine," Appl. Optics, 8, 2369-2370, 1969. 

106. K. K. Thornber and E. H. Turner, "A determination of the electrooptic coefficients of haiiynite, langbeinite and gallium 
phosphide," unpublished. 

107. A. S. Vasilevskaya, I. G. Ganeev, I. S. Rez and A. S. Sonin, "Electrooptic properties of thallium-cadmium langbeinite," 
Sov. Phys.-Cryst. 14, 421-422, 1969. 



15 Linear Electrooptical Materials 459 

108. F. P. Emmenegger, R. Nitsche and A. Miller "Crystal growth and electro-optic effect of some double sulfates with the 
' langbeinite structure," /. Appl. Phys. 39, 3039, 1968. . 

109. R. Bechmann, " Piezooptische and elektrooptische konstanten von piezoelectrische kristallen, Landolt-Bornstein, Zanlen- 
werte and Funktionen," II Band, 8 Teil, " Optische Konstanten ;" K-H and A.M. Hellwege, eds., Springer-Verlag, Berlin, 
1962, pp. 2-453^64. ^ . 

110. A. N. Winchell and H. Winchell, "The microscopical characters of artificial inorganic substances, New York: Academic, 

111. C. F. Buhrer, L. Ho and J. Zucker, " Electrooptic effect in optically active crystals," Appl. Opt., 3, 517-521, 1964. 

112. J. Warner, D. S. Robertson and H. T. Parfit, "The electrooptic effect of sodium uranyl acetate," Phys. Lett., 19, 479^80, 
1965. 

113. T. R. Sliker, "Linear electrooptic effects in class 32, 6, 3m, and 43m crystals," /. Opt. Soc. Am., 54, 1348-1351, 1964. 

114. J. Warner, "The electrooptic effect in proustite (Ag 3 AsA 3 )," Brit. J. Appl. Phys. (J. Phys. D.), 1, 66-67, 1968. 

115. E. H. Turner, I. P. Kaminow and E. D. Kolb, "Electrooptic effect in trigonal selenium at 1.15 microns," IEEE J. Quant. 
Electronics 7, 234, 1968. 

116. L. Gampel and F. M. Johnson, "Index of refraction of single-crystal selenium," /. Opt. Soc. Am., 59, 72-73, 1969. 

117. M. C.TiechandT. Kaplan, " Electrooptic effect in trigonal selenium at 10.6/*m," IEEE J. Quant. Electronics, 2, 702-703, 

118. G. G. Roberts, S. Tutihasi and R. C. Keezer, " Optical absorption-edge of trigonal selenium," Phys. Rev., 1, 637-643, 1968. 

119. V. Prosser, M. Sicha and E. Klier, "Dielectric constant of hexagonal selenium single crystals," in "Recent Advances in 
Selenium Physics," European Selenium-Tellurium Committee, London: Pergamon, 1965, p. 105. 

120. R. Bechmann, "First and second order piezooptic and electrooptic constants of crystals," Landolt-Bornstein, Group III, 
vol. 2, K. H. Hellwege, ed. Springer-Verlag, New York, 1969, pp. 126-166. 

121. W. G. Cady, "Piezoelectricity." New York: McGraw-Hill, 1964, p. 721. 

122. R. D. Rosner, E. H. Turner, I. P. Kaminow, " Clamped electrooptic coefficients of KDP and quartz," Appl. Optics, 6, 779, 

123. H. Pursey and R. J. Newman, " Measurements of the Pockels effect in quartz at 9 GHz," Brit. J. Appl. Phys., (J. Phys. D), 
1, 707-710, 1968. 

124. J. F. Ward and G. H. C. New, " Optical rectification in ammonium dihydrogen phosphate, potassium dihydrogen phosphate 
and quartz," Proc. Roy. Soc. A299, 238-263, 1967. 

125. A. W. Smith and G. Burns, "Optical properties and switching in Gd 2 (Mo0 4 ) 3 ," Phys. Letters, 28 A, 501-502, 1969. 

126. A. R. Johnston and T. Nakamura, "Determination of the low-frequency electro-optic coefficients of NaN0 2 ," /• Appl. 
Phys., 40, 3656-3658, 1969. 

127. O. G. Blokh, I. S. Zheludev and U. A. Shamburov, "The electrooptic effect in crystals of pentaerythntol C(CH 2 OH) 4 , ' 
Soviet Phys.-Cryst., 8, 37-40, 1963. 

128. C. H. Holmes, E. G. Spencer, A. A. Ballman and P. V. Lenzo, "The electrooptic effect in calcium pyroniobate, Appl. 
Opt., 4, 551-553, 1965. 

129. E. H. Turner, unpublished. 

130. V. M. Cound, P. H. Davies, K. F. Hulme and D. Robertson, "The electrooptic coefficients of silver thiogallate (AgGaS 2 ), 
/. Phys. C, 3, L83-L84, 1970. 

131. M. V. Hobden, "Optical activity in a non-enantiomorphous crystal: AgGaS 2 ," Acta Crystallogr., 24A, 676-680, 1968. 

132. E. Nakamura, " Measurement of microwave dielectric constants of ferroelectrics Part II. Dielectric constants and dielectric 
losses of NaNO z and (Glycine) 3 . H 2 S0 4 ," /. Phys. Soc. Jap., 17, 961-966, 1962. 

133. R. D. Rosner and E. H. Turner, "Electrooptic coefficients in calcium pyroniobate," Appl. Optics, 7, 171-173, 1968. 

134. A. Miller, A. G. Karipides and T. M. Peltz, "Enhancement of electro-optic effects at wavelengths in the proximity of elec- 
tronic resonances," to be published. 

135. A. V. Cafiero, A. G. Karipides and A. Miller (unpublished). 

136. A. S. Vasilevskaya, L. I. Kuznetsova, I. S. Rez and A. S. Sonin, "A new crystal with a large electro-optic effect," Sov. 
Phys. Solid State, 10, (5), 733-734, 1968. 

137. Private communication, K. S. Hulme and independently, D. A. Draegert. 

138. A. N. Winchell, "Optical properties of organic compounds," Academic Press, New York, 1954. 



Magnetooptical Materials 

Di Chen 

Honeywell Corporate Research Center 
Hopkins, Minnesota 55343 

The magneto-optic Faraday rotation 4> F is defined as the rotation of the direction of polarization 
of a linearly polarized light in passing through a medium under the influence of an external magnetic 
field or its magnetization. In a paramagnetic or diamagnetic material medium it is given by 

<t> F =VHl cosy, (1) 

where V is the Verdet constant, H is the applied field, / is the path length of the light in the medium 
and y is the angle between the field direction and the beam propagation direction. 

For a ferromagnetic material, the magnetic field H in the above equation is replaced by the mag- 
netization M and the Verdet constant is replaced by the Kundt constant K. A useful physical constant 
of a ferromagnetic material is the Faraday rotation at saturation magnetization M s per unit path 
length, defined as the specific Faraday rotation F for light traveling parallel to M s , i.e., 

F=KM S . (2) 

In utilizing the magneto-optic Faraday rotation in a material medium the optical attenuation must 
also be taken into account. A material figure of merit for paramagnetic and diamagnetic material is 
V/cc, and that for ferromagnetic material is 2F/a, where a is the optical absorption coefficient or ab- 
sorbance from the Beer-Lambert Law, /= I exp(— a/). 

Since the value of the Faraday rotation or specific Faraday rotation is in general a complex 
quantity, subscripts 1 and 2 are used to designate the real and imaginary part respectively. A real 
quantity is assumed when no subscripts are used. The real part of Faraday rotation corresponds to 
the rotation of polarization direction and the imaginary part to the ellipticity of the transmitted light 
beam, which was originally linearly polarized. 

The usual right-hand rule applies to the sign convention of (f> F and F. That is, positive values of 
<j) F and F are associated to the case where the light travels along the direction of the applied field 
or magnetization, and the rotation of the polarization vector is clockwise like a right-hand screw. 



Acknowledgment 

The author gratefully acknowledges contributions by Drs. J. F. Dillon, Jr., C. D. Mee, D. L. Wood, G. Fan, 
W. J. Tabor and especially C. C. Robinson, who has made available unpublished data on certain glasses. 



460 



16 Magnetooptical Materials 461 



TABLE 16-1. FERROMAGNETIC, FERRIMAGNETIC AND 
ANTIFERROMAGNETIC MATERIALS 



The following symbols are used in this table. 

T c = Curie temperature 
T p = Phase transition temperature 
T N = Neel temperature 
T co = Compensation temperature 
AttM,, = Saturation induction at 0°K, gauss 



F= Specific Faraday rotation, deg/cm 
a = Absorption coefficient, cm -1 
2F/a. = Figure of merit, degrees 
T = Temperature, °K 
A = Measurement wavelength, m\i 



Structure! ^.^ 

composi- _ 47tM s 
,. o/ temp. 
tion,% y 


F 


a. 


2F/oc 


T 


A 


Ref. 


Remark 


TRANSITION METALS 



bec 



r c =1043 21,800 



hep 



T c =1390 18,200 



fee 



T c = 633 



6,400 



IRON 



3.5 x 10 5 


7.6 x 10 5 


0.92 


300 


546 


1 




5.1 x 10 5 


3.2 x 10 5 


3.1 


300 


1000 


2,3 




4.4 x 10 5 


6.5 x 10 5 


1.4 


300 


500 


4 


a 


6.5 x 10 5 


5 x 10 5 


2.6 


300 


1000 


4 


a 


7 x 10 5 


4.2 x 10 5 


3.3 


300 


1500 


4 


a 


7 x 10 5 


3.5 x 10 5 
COBALT 


4.0 


300 


2000 


4 


a 


3.6 x 10 5 


8.5 x 10 5 


0.85 


300 


546 


1 




2.9 x 10 s 


- 


- 


300 


500 


4 


a 


5.5 x 10 5 


6.1 x 10 5 


1.8 


300 


1000 


4 


a 


5.5 x 10 5 


4.5 x 10 5 


2.4 


300 


1500 


4 


a 


4.8 x 10 5 


3.6 x 10 5 
NICKEL 


2.7 


300 


2000 


4 


a 


0.99 x 10 5 


8.0 x 10 5 


0.25 


300 


546 


1 




7.2 x 10 5 


4.2 x 10 s 


3.4 


300 


4000 


2,3 




0.8 x 10 5 


- 


- 


300 


500 


4 


a 


2.6 x 10 5 


5.8 x 10 5 


0.9 


300 


1000 


4 


a 


1.5 x 10 5 


4.8 x 10 5 


0.6 


300 


1500 


4 


a 


1 x 10 5 


4.1 x 10 5 


0.25 


300 


2000 


4 


a 


NICKEL SINGLE CRYSTAL FILM 










0.79 x 10 s 


- 


- 


300 


546 


5 


b 


0.88 x 10 5 


- 


- 


300 


546 


5 


c 


0.97 x 10 5 


- 


- 


300 


546 


5 


d 



BINARY COMPOUNDS AND ALLOYS 



fee/ 


Ni: 


82 


Fe: 


18 


Ni 


:Fe% 


100 





90 


10 



PERMALLOY 

r c = 803 10,700 1.2 x10 s 6 x10 s 0.4 

NICKEL-IRON 

6,000 1.2 x10 s 7.05 x10 s 0.34 
8,400 1.6 x10 s 7.14 x10 s 0.45 



300 



300 
300 



500 



632.8 
632.8 



6,7 



8,9 
8,9 



Refer to Fig. 16-l(a) for F and 16-l(b) for a of Fe, Co, Ni in the wavelength region from 500 to 2500 m/x (Reference (1)). 
For light beam transmission in the <100> direction. 
For light beam transmission in the <110> direction. 
For light beam transmission in the <1 1 1 > direction. 



462 



Handbook of Lasers 



- o.i 

1 
u. 

-0.1 
-0.2 
-0.3 
-0.4 
-0.5 
-0.61- 



F, (IRON) 




0.5 



^°N 



\ 1.5 2.0 2.5 

v^ \ WAVELENGTH K IN MICRONS 

N T % v F 2 (NICKEL) 



\ 



'\ 



\ 



F,(IR0N) 



F 2 (C0BALT) 



XlO 

' E 7.0 
o 

c 

O 

,_ 6.0 

z 

UJ 

o 



o 
o 



5.0 



4.0 



Q. 
O 

(/> 3.0 

OD 

< 



2.0 



1.0 



COBALT 




0.5 



1.0 1.5 

WAVELENGTH X IN MICRONS 



2.0 



Fig. 16-1. Wavelength dependence of (a) specific Faraday rotation F=Fi + iF 2 in degrees/cm 
and (b) the absorption coefficient a in cm -1 of iron, cobalt and nickel at room temperature. 1 



16 Magnetooptical Materials 463 



TABLE 16-1. FERROMAGNETIC, FERRIMAGNETIC AND 
ANTIFERROMAGNETIC MATERIALS (Continued) 



Structure/ 

composi- 

tion,% 


Critical 
temp. 


4ttM s 


F 


a 


2F/oc 


T 


A 


Ref. 


Remark 








NICKEL-IRON (Continued) 










80:20 




10,800 


2.2 x 10 s 


7.10 x 10 s 


0.62 


300 


632.8 


8,9 




70:30 




12,900 


2.7 x 10 s 


7.0 x 10 5 


0.77 


300 


632.8 


8,9 




60:40 




14,900 


2.9 x 10 s 


7.54 x 10 5 


0.77 


300 


632.8 


8,9 




50:50 




16,000 


2.8 x 10 s 


8.13 x 10 5 


0.69 


300 


632.8 


8,9 




40:60 




14,400 


2.2 x 10 5 


8.17 x 10 5 


0.54 


300 


632.8 


8,9 




30:70 




8,000 


- 


8.13 x 10 5 


- 


300 


632.8 


8,9 




20:80 




19,400 


3.3 x 10 5 


8.1 x 10 5 


0.81 


300 


632.8 


8,9 




10:90 




20,800 


3.6 x 10 5 


8.13 x 10 5 


0.88 


300 


632.8 


8,9 




0:100 




21,600 


3.5 x 10 5 


8.13 x 10 5 


0.86 


300 


632.8 


8,9 




35:65 




12,400 


2.1 x 10 s 


7.7 x 10 s 
MnBi 


0.55 


300 


400-700 


10 




Normal 


T c = 639 


7,700 


4.2 x 10 5 


6.1 x 10 5 


1.4 


300 


450 


11, 12 


a 


(l.t.p.): 




(7,500 at 5.0 x 10 5 


5.8 x 10 5 


1.7 


300 


500 


11, 12 


a 


NiAs 




300°K) 


7.0 x 10 s 


5.1 x 10 5 


2.8 


300 


600 


11, 12 


a 








7.7 x 10 5 


4.5 x 10 5 


3.4 


300 


700 


11, 12 


a 








7.6 x 10 5 


4.3 x 10 5 


3.5 


300 


800 


11, 12 


a 








7.5 x 10 s 


4.2 x 10 5 


3.6 


300 


900 


11, 12 


a 








7.4 x 10 5 


4.1 x 10 5 


3.6 


300 


1000 


11, 12 


a 


Quenched 


T c = 453 


(5500 at 


3.2 x 10 s 


6.1 x 10 s 


1.0 


300 


450 


11, 12 


a 


(h.t.p.): 




300°K) 


3.3 x 10 s 


5.8 x 10 5 


1.1 


300 


500 


11, 12 


a 


distorted 






3.3 x 10 5 


5.1 x 10 5 


1.3 


300 


600 


11,12 


a 


NiAs 






3.3 x 10 5 


4.7 x 10 5 


1.4 


300 


700 


11, 12 


a 








3.3 x 10 s 


4.5 x 10 5 


1.4 


300 


800 


11, 12 


a 








3.2 x 10 s 


4.4 x 10 s 


1.4 


300 


900 


11, 12 


a 








3.2 x 10 5 


4.4 x 10 5 
MnAs 


1.4 


300 


1000 


11, 12 


a 


NiAs 


r c = 313 




0.44 x 10 s 


5.0 x 10 s 


0.174 


300 


500 


13 










0.49 x 10 s 


4.9 x 10 5 


0.200 


300 


600 


13 










0.59 x 10 s 


4.6 x 10 s 


0.26 


300 


700 


13 










0.78 x 10 s 


4.5 x 10 5 


0.34 


300 


800 


13 










0.62 x 10 s 


4.4 x 10 s 
CrTe 


0.28 


300 


900 


13 




NiAs 


T c = 334 


1015 


0.5 x 10 5 


2.0 x 10 5 


0.5 


300 


550 


14 










0.4 x 10 5 


1.2 x 10 5 


0.7 


300 


900 


14 










0.4 x 10 5 


0.6 x 10 s 
FeRh 


1.3 


300 


2500 


14 






T p = 333 




0.9 x 10 5 


3.3 x 10 5 


0.56 


348 


700 


15 




FERRITES 










YIG 












Garnet 


7* = 560 


2500 


240 


0.069 


7 x 10 3 


300 


1200 


16, 17 
18, 19 


b 








2400 


1500 


3.2 


300 


555 


16, 17 
18, 19 


b 



a Refer to Fig. 16-2 forF, a and 2F/a of MnBi in the wavelength region from 200 to 1200 m/x. at room temperature 
(reference 11, 12). 

b Refer to Fig. 16-4(a) for a and Fig. 16-4(b) for 2F/x of YIG in the infrared wavelength region, and Fig. 16-4(c) for a 
and F in the visible wavelength region. The data to the left of P and P' in Fig. 16-4(b) represent the lower limit; the dashed lines 
are the expected values. 



464 



Handbook of Lasers 




o 

UJ 
0. 

in 



1.0- 



200 



2F/a (QUENCHED) 



400 600 800 

WAVELENGTH IN m/u. 



1000 



4.0 



3.5 

UJ 

3.0 «** 
o 

UJ 

o 
2.5 z 

a 

I li- 
2.0 " 

t 

UJ 

1.5 s 



UJ 

1.0 ^ 
o 



0.5 



1200 



Fig. 16-2. Wavelength dependence of the specific Faraday rotation F in degrees/cm, absorp- 
tion coefficient a in cm -1 , and figure of merit 2F/a in degrees pf MnBi at room temperature. 11 



> o 



UJ 

2 



UJ 
O 




1.0 1.5 

X (MICRONS) 

Fig. 16-3. Wavelength dependence of the figure of merit V/cc in minutes/Oe of various optical glasses: 



16 Magnetooptical Materials 465 



TABLE 16-1. FERROMAGNETIC, FERRIMAGNETTC AND 
AJNTITFERROMAGNETIC MATERIALS (Continued) 



Structure/ 
composi- 
tion 


Critical 
temp. 


4itM s 


F 


a. 


2F/oc 


T 


A 


Ref. 


Remark 








YIG {Continued) 


















1750 


1350 


2.6 


300 


588 


16, 17 
18, 19 


a 








1250 


1400 


1.8 


300 


625 


16, 17 
18, 19 


a 








800 


1150 


1.4 


300 


667 


16, 17 
18, 19 


a 








900 


670 


2.7 


300 


715 


16, 17 
18, 19 


a 








750 


450 


3.3 


300 


770 


16, 17 
18, 19 


a 








175 


<.06 
GdIG 


>3 x 10 3 


300 


5000- 
1500 


16, 17 
18, 19 


a 


Garnet 


7W = 564 


7300 


-2000 


6000 


0.6 


300 


500 


18-21 


b 




T co = 286 




-1050 


900 


2.3 


300 


600 


18-21 










-450 


400 


2.3 


300 


700 


18-21 










-300 


100 


6 


300 


800 


18-21 


b 








-220 


230 


1.9 


300 


900 


18-21 


b 








-80 


70 
NiFeO* 


2.3 


300 


1000 


18-21 


b 


Spinel 


T N = 858 


3350 


2.0 x 10* 


5.9 x 10 4 


0.7 


300 


286 


22,23 










2.4 x 10 4 


7.4 x 10 4 


0.7 


300 


330 


22,23 










-0.75 x 10* 


16 x 10 4 


0.09 


300 


400 


22,23 










-1.0 x 10 4 


10 x 10 4 


0.2 


300 


500 


22,23 










+0.12 x 10 4 


1 x 10 4 


0.2 


300 


660 


22,23 










-120 


38 


6 


300 


1500 


22,23 










+40 


32 


2.5 


300 


2000 


22,23 










+75 


15 


10 


300 


3000 


22,23 










+ 110 


15 


15 


300 


4000 


22,23 










+ 110 


32 
CoFe 2 4 


7 


300 


5000 


22,23 




Spinel 


T N = 793 


4930 


2.75 x 10 4 


12 x 10 4 


0.5 


300 


286 


22,23 










3.8 x 10 4 


14 x 10 4 


0.5 


300 


330 


22,23 










3.6 x 10 4 


17 x 10 4 


0.4 


300 


400 


22,23 










1.3 x 10 4 


13 x 10 4 


0.2 


300 


500 


22,23 










-2.5 x 10 4 


6x 10 4 
MgFe 2 4 


0.8 


300 


660 


22,23 










-60 


100 


1 


300 


2500 


24 










-40 


40 


2 


300 


3000 


24 













12 





300 


4000 


24 










+30 


4 


15 


300 


5000 


24 










+35 


6 


11 


300 


6000 


24 










+50 


13 


8 


300 


7000 


24 





" Refer to Fig. 16-4(a) for a and Fig. 16-4(b) for 2F/a of YIG in the infrared wavelength region, and Fig. 16-4(c) for a 
and F in the visible wavelength region. The data to the left of P and P' in Fig. 16-4(b) represent the lower limit; the dashed lines 
are the expected values. 

b Refer to Fig. 16-5(a), for F, 16-5(b) for a and 16-5(c) for 2F/oc of GdIG measured in the visible wavelength at room 
temperature. 



466 



Handbook of Lasers 



xlO" 



2 
o 

z 

a 




J L 



5 6 7 8 9 10 
xl0 3 CM" 1 
WAVE NUMBER 

(a) 




8 9 10 
xl0 3 CM"' 
WAVE NUMBER 

(b) 



2800 



2400- 



o 2000 h 



1600- 



o. 

O 
(/> 
CD 

< 



1200- 



800- 



400- 




14 16 

ENERGY IN CM 

(C) 



18 
-l 



Fig. 16-4. Wavelength dependence of (a) absorption coefficient a in cm" 1 , (b) figure of merit IF /a in de- 
grees in the infrared wavelength and (c) room temperature absorption coefficient a and specific Faraday rota- 
tion in degrees/cm in the visible wavelength of YIG. [(a) and (b) are from ref. 16; (c) from ref. 19.] 



16 Magnetooptical Materials 467 



o 

CO 

u 
u 

(X. 

o 
u 
o 



Si 

I- 
o 
a: 

> 
< 

< 

a 




4000 6000 8000 
WAVELENGTH, A 

(a) 



1 0000 



2000 4000 6000 8000 I0000 
WAVELENGTH.A 

(b) 



Fig. 16-5. Wavelength dependence of (a) specific Faraday rotation in degrees/cm and (b) absorption coeffi- 
cient in cm -1 of GdlG. The numerals indicate: (1) 0.7 /xm polycrystalline sample on glass substrate (2) 1.0 
/xm sample on (111) oriented YAG substrate and (3), single crystal samples. 20 



2 3 




Fig. 16-5. (c) Wavelength depend- 
ence of figure of merit 2F/a in degrees 
for a hot pressed GdlG sample. 21 



'xlO 3 



1 5 


- 


/""N. T « 5°K 


a. 

> 3 

<t 
o 2 

« 

u. 




i i i i 


r \ H * 20.8k0e 
\ t * I530A 
\ M II T 

i i \ I i I i 


1 - 
a. -2 

CO 


- 




10 






8 






'S 6 






° 4 






2 









i i i i 


L _.iii T 1 i 



300 



500 



700 



900 



1100 



1300 



WAVELENGTH (m^) 

Fig. 16-6. Wavelength dependence of the specific 
Faraday rotation in degrees/cm measured at 5°K and 
absorption coefficient measured at 8°K for EuO. 38 



468 



Handbook of Lasers 



TABLE 16-1. FERROMAGNETIC, FERRBMAGNETIC AND 
ANTIFERROMAGNETIC MATERIALS (Continued) 



Structure/ 
composi- 
tion 



Critical 
temp. 



4ttM. 



2F/at 



Ref. Remark 



Hexagonal 



Hexagonal 





Lio.5Fe2.5O4 










-440 


150 


6 


300 


1500 


24 


-190 


135 


3 


300 


2000 


24 


+ 10 


85 


0.2 


300 


3000 


24 


+ 85 


60 


3 


300 


4000 


24 


+ 110 


44 


5 


300 


5000 


24 


+ 125 


44 


6 


300 


6000 


24 


+ 135 


80 
BaFei 2 Oi9 


3 


300 


7000 


24 


-50 


-38 


3 


300 


2000 


24 


+75 


20 


7.5 


300 


3000 


24 


+ 130 


13 


20 


300 


4000 


24 


+ 150 


20 


15 


300 


5000 


24 


+ 160 


20 


16 


300 


6000 


24 


+ 165 


22 
Ba 2 Zn 2 Fe 12 1 9 


15 


300 


7000 


24 


+90 


120 


1.5 


300 


5000 


24 


+80 


70 


2 


300 


6000 


24 


+75 


65 


2 


300 


7000 


24 


+70 


85 


2 


300 


8000 


24 



FLUORIDES 











RbNiF 3 












Perov- 


T„ = 220 


1250 


360 


35 


20 


77 


450 


25 


a 


skite 






210 


12 


35 


77 


500 


25 


a 








70 


10 


14 


77 


600 


25 


a 








-70 


30 


5 


77 


700 


25 


a 








310 


70 


9 


77 


800 


25 


a 








100 


60 


3 


77 


900 


25 


a 








75 


25 
RbNio.75Coo.25F3 


6 


77 


1000 


25 


a 


Perov- 


r N =i09 




180 


9 


40 


77 


600 


26 


b 


skite 








RbFeF 3 








27 




Perov- 


T p = 102 




3400 


7 


900 


82 


300 


28 


c 


skite 






1600 


3 


1100 


82 


400 


28 


c 








950 


4.6 


410 


82 


500 


28 


c 








620 


1.5 


830 


82 


600 


28 


c 








420 


1.2 


700 


82 


700 


28 


c 








300 


2.5 
FeF 3 


240 


82 


800 


28 


c 




T c = 365 


40 


670 


14 


95 


300 


349 


29 


d 






(300°K) 


415 


8.2 


101 


300 


404 


29 


d 








180 


4.4 


82 


300 


522.5 


29 


d 



" Measured along the c-axis, which is the magnetic hard axis. 
b Measured along the c-axis, which is the magnetic easy axis. 
c Measured along the c-axis ([100] direction at room temperature). 
d Strong natural birefringence interferes with the Faraday effect. 



16 Magnetooptical Materials 469 

TABLE 16-1. FERROMAGNETIC, FERRIMAGNETIC AND 
ANITFERROMAGNETIC MATERIALS (Continued) 



Structure/ 
composi- 
tion 



Critical 
temp. 



4ttM s 



2F/oc 



Ref. Remark 



TRIHALIDES 



CrCI 3 



Bil 3 


T c =i6.8 


3880 


2000 


200 


20 


1.5 


410 








-500 


300 


3 


1.5 


450 








-1000 


70 
CrBr 3 


30 


1.5 


590 


Bil 3 


T c = 32.5 


3390 


3x 10 5 


3x 10 3 


200 




478 








1.6 x 10 s 


1.4 x 10* 
Crl 3 


23 


1.5 


500 


Bil 3 


T c = 68 


2690 


1.1 x 10 5 


6.3 x 10 3 


35 


1.5 


970 








0.8 x 10 5 


3x 10 3 


53 


1.5 


1000 



34,35 



36 



34,37 



BORATES 



FeBO, 



Calcite 



T c = 348 



115 


3200 


140 


45 


300 


500 


29 


b 


(300°K) 


2300 


40 


115 


300 


525 


29 


b 




1100 


100 


22 


300 


600 


29 


b 




450 


38 


24 


300 


700 


29 


b 



CHALCOGENIDES 



NaCl 



7; = 69 



23,700 



NaCl 



16.3 



NaCl 



T c = l 



13,200 



EuO 



-1.0 x 10 5 


0.5 x 10* 


40 


5 


1100 


38,39 


c 


+3.2 x 10 5 


7.5 x 10* 


8.5 


5 


800 


38,39 


c 


+5 x 10 5 


9.7 x 10* 


10 


5 


700 


38,39 


c 


+3.6 x 10 5 


9.7 x 10* 


7.5 


5 


600 


38,39 


c 


+0.5 x 10 5 


7.8 x 10* 


1.3 


5 


500 


38, 39 


c 


3 x 10 4 


>0.5 


-10 s 


20 


2500 


40 




660 


>1.0 
EuS 


~130O 


20 


10600 


40 




-1.6 x 10 5 


~0 


- 


6 


825 


41 




-9.6 x 10 5 


3.3 x 10* 


58 


6 


690 


41 




+5.5 x 10 5 


1.2 x 10 5 


92 


6 


563 


41 




+5.1 x 10 5 


1.0 x 10 5 
EuSe 


10 


6 


495 


41 




1.45 x 10 5 


80 


3600 


4.2 


750 


42 




1.17 x 10 5 


70 


3340 


4.2 


775 


42 




0.95 x 10 5 


60 


3170 


4.2 


800 


42 





Refer to Fig. 16-7 for a and Fof CrCl 3 , CrBr 3 and Crl 3 at 1.5°K in the visible wavelength (reference 34). 

Strong natural birefringence interferes with the Faraday effect. 

Refer to Fig. 16-6 for a at 8°K and F at 5°K of EuO in the visible wavelength (reference 38). 



470 



Handbook of Lasers 



XIO 



UJ 

o 

b. 
U. 
UJ 
O 
O 



CL 

rr 
o 
(/) 

CD 




10' 



8 
6 

4 
2h 















i 




Crl 3 


. 


•4 


J 




— 




< 1 1 1 1 


i i i i 





xlO 



52 



1.5 o 
u 



- 1.0 



8 



12 14 16 18 20 22 
PHOTON ENERGY (CM' 1 ) 



24 26 



Fig. 16-7. Wavelength dependence of the absorption coefficient in cm 1 and the specific Faraday rotation 
in degrees/cm CrCl 3 , CrBr 3 and Crl 3 . (From ref. 34 by courtesy of Pergamon Press.) 



16 Magnetooptical Materials 471 

TABLE 16-1. FERROMAGNETIC, FERRIMAGNETIC AND 
ANTIFERROMAGNETIC MATERIALS (Continued) 



Material 



Saturation 

induction 

AttM s in 

gauss 



Intrinsic specific Faraday rotation in °jcm 

at 300° K at wavelength in m[L 
600 800 1,000 1,200 1,400 1,600 



Absorption 
coefficient 
a. in cm~ l at 
wavelength 
l,250m/n 



Ref. 



Remark 



ORTHOFERRITES 



EuFe0 3 


83 










GdFe0 3 


94 










TbFe0 3 


137 










DyFe0 3 


128 










HoFe0 3 


91 } ||"c" 


8000 


2200 


1000 


ErFe0 3 


81 










TmFe0 3 


140 










YbFe0 3 


143 










LuFe0 3 


119j 










SmFe0 3 


84 ||"a" 


3400 


700 


400 


YFe0 3 


105 








LaFe0 3 


83 








PrFe0 3 


71 








NdFeQ 3 


62 











800 700 



300 200 



600 



150 



38 


30-33 


a 


10 


30-33 


a 


29 


30-33 


a 


40 


30-33 


a 


10 


30-33 


a 


15 


30-33 


a 


5 


30-33 


a 


12.5 


30-33 


a 


5 


30-33 


a 


50 


30-33 


a 


10 


30-33 


a 


10 


30-33 


a 


35 


30-33 


a 


10 


30-33 


a 



Strong natural birefringence interferes with the Faraday effect. 



472 Handbook of Lasers 

TABLE 16-2. PARAMAGNETIC MATERIALS 



Rare earth 



Host 
material 



Valency 



Measurement 

temperature 

in°K 



Measurement 
wavelength in mjx 



Verdet 

constant 

min/Oe-cm 



Absorption 

coefficient 

in cm -1 



V/<x in 
min/Oe 



Ref. 



RARE EARTH IONS IN CRYSTALS 



Eu 3% 


CaF 2 


2+ 


4.2 


430 


29 


11.5 


2.5 


43 








4.2 


440 


22 


1.8 


12 


43 


Nd 2.9% 


CaF 2 


3 + 


4.2 


426.4 


0.19 


5 


0.04 


43 


Eu 


EuF 2 


2 + 


300 


450 


4.5 


20 


0.2 


42 








300 


500 


2.6 


7 


0.4 


42 








300 


550 


1.6 


6 


0.3 


42 








300 


600 


1.1 


5.5 


0.2 


42 








300 


650 


0.8 


5 


0.16 


42 



Material 



Measurement 

temp. 

°K 



Measurement 
wavelength 
in mfj. 



Verdet 

constant V in 

min/Oe-cm 



Wavelength 

in m\i at 

oc = 10*cm- 1 



Wavelength 
in mfji 
at <x = \crn~ 1 



Ref. 



PEROVSKITES {OXIDES) 



SrTiO, 



298 



BaTa0 3 403 



KTa0 3 296 



413 


0.78 


496 


0.31 


620 


0.14 


826 


0.066 


427 


0.95 


496 


0.38 


620 


0.18 


826 


0.072 


352 


0.44 


413 


0.19 


496 


0.096 


620 


0.051 


826 


0.022 



368 



380 



327 



413 



446 



370 



Material Temp. °K 



405 



450 



Verdet constant in min/Oe-cm 
at wavelength m\i 
480 520 546 578 



635 



670 



44 



44 



44 



Ref. 



RARE EARTH ALUMINUM GARNETS 


TbAlG* 300 


-2.266 


-1.565 


-1.290 


-1.039 


-0.912 


-0.787 


-0.620 


-0.542 


46 


77 








-3.425 


-3.051 


-2.603 


-2.008 


-1.815 


46 


4.2 




-102.16 


-83.45 


-64.80 


-58.35 


-53.77 


-48.39 


-45.15 


45 


1.45 




-200.95 


-172.52 


-139.28 


-125.07 


-111.27 


-97.47 


-93.42 


45 


DyAlG 300 


-1.241 


-0.942 


-0.803 


-0.667 


-0.592 


-0.518 


-0.411 


-0.359 


46 


HoAlG 300 


-0.709 


-0.320 


-0.260 


-0.335 


-0.304 


-0.299 




-0.206 


46 


ErAlG 300 


-0.189 


-0.240 


-0.154 


-0.162 


-0.157 


-0.145 


-0.105 


-0.089 


46 


TmAlG 300 


+0.151 


+0.103 


+0.093 


0.076 


0.069 


+0.059 


+0.048 




46 


YbAlG 298 


0.287 


0.215 


0.186 


0.140 


0.133 


0.116 


0.094 




47 


77 


0.718 


0.540 


0.481 


0.393 


0.342 


0.302 


0.239 




47 



* Absorption coefficient, a = 0.2-0.6 cm -1 at room temperature. 



16 Magnetooptical Materials 473 



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476 Handbook of Lasers 

TABLE 16-3. GLASSES (Continued) 



Glass type 



Composition, 
wt% 



Verdet constant at 

room temperature 

in min/Oe-cm 

at wavelength in m/A 

700 853 1060 



Ref. 



MISCELLANEO US 



Bi 2 3 
PbO 



T1,0 



SnO 
TeO, 



Sb 2 3 



95 Bi 2 3 , 5B 2 3 

95 PbO, 5B 2 3 

82 PbO, 18 Si0 2 

50 PbO, 15 K 2 0, 35 Si0 2 

95 T1 2 0, 5 B 2 3 

82 T1 2 0, 18 Si0 2 

50 T1 2 0, 15 K 2 0, 35 Si0 2 

76 SnO, 13B 2 3 , 11 Si0 2 

75 Te0 2 , 25 Sb 2 3 

80 Te0 2 , 20 ZnCl 2 

84 Te0 2 , 16BaO 

70 TeO 2 ,30WO 3 

20 Te0 2 , 80 PbO 

25 Sb 2 3 , 75 Te0 2 

75 Sb 2 3 , Cs 2 0, 5A1 2 3 

75 Sb 2 3 10 Cs 2 0, 10 Rb 2 0, 5 A1 2 3 



.086 


.051 


.033 


54 


.093 


.061 


.031 


54 


.077 


.045 


.027 


54 


.032 


.020 


.011 


54 


.092 


.061 


.032 


54 


.100 


.067 


.043 


54 


.036 


.022 


.012 


54 


.071 


.046 


.026 


54 


.076 


.052 


.032 


54 


.073 


.046 


.025 


54 


.056 


.041 


.029 


54 


.052 


.035 


.022 


54 


.128 


.075 


.048 


54 


.076 


.050 


.032 


54 


.074 


.044 


.025 


54 


.078 


.052 


.030 


54 



Glass type Si0 2 



Composition, % 
B 2 3 K 2 CaO A1 2 3 As 2 3 Na 2 BaO 



ZnO PbO 



BSC 


69.6 


6.7 


20.5 


2.9 


0.3 


0.1 


- 


- 


- 


- 


HC 


72.0 


- 


10.1 


11.4 


0.3 


0.2 


6.1 


- 


- 


- 


LBC 


57.1 


1.8 


13.7 


0.3 


0.2 


0.1 


- 


26.9 


- 


- 


LF 


52.5 


- 


9.5 


0.3 


0.2 


0.1 


- 


- 


- 


37.6 


BLF 


45.2 


- 


7.8 


- 


- 


0.4 


- 


16.0 


8.3 


22.2 


DBC 


36.2 


7.7 


0.2 


0.2 


3.5 


0.7 


- 


44.6 


6.7 


- 


DF 


46.3 


- 


1.1 


0.3 


0.2 


0.1 


5.0 


- 


- 


47.0 


EDF 


40.6 


- 


7.5 


0.2 


0.2 


0.2 


0.1 


- 


- 


51.5 



Glass type Density 



N D 



Verdet constant at room temperature 

in min/Oe-cm at 

wavelength in mfi 

365.0 404.7 435.8 546.1 578.0 



Ref. 



BSC 


2.49 


1.5096 


0.0499 


0.0392 


0.0333 


0.02034 


0.01798 


55 


HC 


2.53 


1.5189 


0.0561 


0.0440 


0.0372 


0.0225 


0.01995 


55 


LBC 


2.87 


1.5406 


0.0609 


0.0477 


0.0403 


0.0245 


0.0216 


55 


LF 


3.23 


1.5785 


0.1143 


0.0850 


0.0693 


0.0394 


0.0344 


55 


BLF 


3.48 


1.6047 


0.1112 


0.0832 


0.0685 


0.0393 


0.0344 


55 


DBC 


3.56 


1.6122 


0.0662 


0.0517 


0.0435 


0.0261 


0.0231 


55 


DF 


3.63 


1.6203 


0.1473 


0.1076 


0.0872 


0.0485 


0.0423 


55 


EDF 


3.9 


1.6533 


0.1725 


0.1248 


0.1007 


0.0556 


0.0483 


55 



REFERENCES 



1. W. Breuer and J. Jaumann, Z. Physik, 173, 117, 1963. 

2. Landolt-Borstein, "Optische Konstanten" 6th ed., Bd II 18, Springer- Verlag, Berlin, 1962. 

3. G. S. Krinchik, Fiz. Metalloved. 5, 694, 1959. 

4. K. H. Clemens and J. Jaumann, Z. Physik, 173, 135, 1963. 

5. O. S. Heavens and R. F. Miller, Proc. Roy. Soc. A. 266, 547, 1962. 

6. R. M. Bozorth, " Ferromagnetism," Van Nostrand Inc., New York, 1951, p. 102. 

7. C. C. Robinson,/. Opt. Soc. Am. 53, 681, 1963. 

8. "American Institute of Physics Handbook," 5-207, 1958. 

9. L. V. Kirenskii, N. I. Syrova and I. S. Edelman, Dokl. Akad. Nauk SSSR, 175, 413 (1967), in Russian; English translation 
in Sov. Phys. Dokl. 12, 819, 1968. 



16 Magnetooptical Materials 477 

10. H. H. Weider and D. A. Collins, Appl. Opt. 2, 411, 1963. 

11. D. Chen, R. L. Aagard and T. S. Liu, /. Appl. Phys. 40, 1395, 1970. 

12. D. Chen and R. L. Aagard, /. Appl. Phys. 41, 2530, 1970. 

13. A. M. Stoffel and J. Schneider, /. Appl. Phys. 41, 1405, 1970. 

14. R. L. Comstock and P. H. Lissberger, /. Appl. Phys. 41, 1397, 1970. 

15. A. M. Stoffel, /. Appl. Phys. 40, 1238, 1969. 

16. R. C. LeCraw, D. L. Wood, J. F. Dillon, Jr., and J. P. Remeika, Appl. Phys. Lett. 7, 27, 1965. 

17. C. D. Mee, Contemp. Phys. 8, 385, 1967. 

18. R. Pouthenet, /. Appl. Phys. 29, 253, 1958. 

19. J. F. Dillon, Jr., /. Phys. Radium, 20, 374, 1959, and /. Appl. Phys. 29, 539, 1958. 

20. R. E. MacDonald and J. W. Beck, /. Appl. Phys. 40, 1429, 1969. 

21. P. Coeure, F. Forrat and J. C. Gay, IEEE Trans, MAGS, 289, 1969. 

22. E. W. Gorter, Proc. IRE, 43, 1945, 1955. 

23. R. L. Coren and M. H. Francombe, /. Phys. Radium, 25, 233, 1964. 

24. G. Zanmarchi and P. F. Bongers, /. Appl. Phys. 40, 1230, 1969. 

25. M. W. Shafer, T. R. McGuire B. E. Argyle and G. Fan, Appl. Phys. Lett. 10, 202, 1967. 

26. J. C. Suits, T. R. McGuire and M. W. Shafer, IEEE MAG-4, 425, 1968. 

27. R. V. Pisarev, I. G. Sing, N. N. Nesterova, G. A. Smolensky and P. P. Syrnikov, Phys. Stat. Sol. 30, 367, 1968. 

28. F. S. Chen, H. J. Guggenheim, H. J. Levinstein and S. Singh, Phys. Rev. Lett. 19, 948, 1967. 

29. R. Wolfe, A. J. Kurtzig and R. C. LeCraw, /. Appl. Phys. 41, 1218, 1970. 

30. A. H. Bobeck, R. F. Fischer, A. J. Perneski, J. P. Remeika and L. G. Van Uitert, IEEE MAGS, 544, 1969. 

31. W. J. Tabor, A. W. Anderson and L. G. Van Uitert, /. Appl. Phys., 41, 3018, 1970. 

32. M. V. Chetkin and Yu. I. Shcherbakov, Sov. Phys. Sol. 11, 1314, 1969. 

33. D. L. Wood, J. P. Remeika and E. D. Kolb, to be published. 

34. J. Dillon, Jr., H. Kamimura, and J. P. Remeika, /. Phys. Chem. Solids, 27, 1531, 1966. 

35. A. Narath, Phys. Rev. 131, 1929, 1963. 

36. J. F. Dillon, Jr., H. Kamimura and J. P. Remeika, Phys. Rev. Lett. 9, R529-1, 1962 and also /. Appl. Phys. 34, 1240, 1963. 

37. J. F. Dillon, Jr., and C. E. Olson, /. Appl. Phys. 36, 1259, 1965. 

38. K. Y. Ahn and J. C. Suits, IEEE MAGS, 453, 1967. 

39. B. T. Matthias, R. M. Bozorth and J. H. Van Vleck, Phys. Rev. Lett. 7, 160, 1961. 

40. J. O. Dimmock, C. E. Hurwitz and T. B. Reed, Appl. Phys. Lett. 14, 49, 1969. 

41. G. Guntherodt, J. Schoenes and P. Wachter, /. Appl. Phys. 41, 1083, 1970. 

42. J. C. Suits, B. E. Argyle and M. J. Freiser, /. Appl. Phys. 37, 1391, 1966. 

43. Y. R. Shen and N. Bloembergen, Phys. Rev. 133, A515, 1964. 

44. W. S. Baer, /. Chem. Solids, 28, 677, 1967. 

45. W. Desorbo, Phys. Rev. 158, 839, 1967. 

46. C. B. Rubinstein, L. G. Van Uitert and W. H. Grodkiewicz, /. Appl. Phys. 35, 3069, 1964. 

47. C. B. Rubinstein and S. B. Berger, /. Appl. Phys. 36, 3951, 1965. 

48. M. W. Shafer and J. C. Suits, /. Am. Ceramic Soc. 49, 261, 1966. 

49. C. B. Rubinstein, S. B. Berger, L. G. Van Uitert and W. A. Bonner, /. Appl. Phys. 35, 2338, 1964. 

50. C. C. Robinson and R. E. Graf, Appl. Opt. 3, 1190, 1964. 

51. S. B. Berger, C. B. Rubinstein, C. R. Kurkjian and A. W. Treptow, Phys. Rev. 133, A723, 1964. 

52. C. C. Robinson, Appl. Opt. 3, 1163, 1964. 

53. C. C. Robinson and A. Cleri, private communication. 

54. N. F. Borrelli, /. Chem. Phys. 41, 3289, 1964. 

55. V. Sivaramakrishnan, /. India Inst. Sci. A, 39, 19, 1957. 



Elastooptical Materials 

Douglas A. Pinnow 

Bell Telephone Laboratories, Incorporated 
Murray Hill, New Jersey 07974 

INTRODUCTION 

The photoelastic effect in a material couples mechanical strain to the optical index of refraction. 
This effect is important to laser applications for two principal reasons. First, it leads to a class of active 
optical devices such as switches, modulators, 1,2 correlators, 3 " 5 filters, 6 and scanners, 7 " 9 which are 
driven by launching an acoustic (strain) wave into a medium through which a light beam passes. In the 
presence of such a strain wave, the photoelastic effect causes the medium to respond as an optical phase 
grating. The grating spacing is equal to the acoustic wave length, which can be varied by changing the 
driving frequency, while the grating depth is determined by the drive power. A large elasto-optic inter- 
action is desired for all such devices. On the other hand, the photoelastic effect degrades the performance 
of optical materials such as solid state laser hosts, and glass used to make lenses, etc., since frozen-in or 
thermally induced strains cause optical phase distortions. A minimum elasto-optic interaction is obviously 
desired in these cases. 

The details of the photoelastic effect in amorphous and crystalline materials are presented below and 
experimental results are tabulated. The operation of acousto-optic devices is summarized and related to 
various material properties, which are also tabulated. 

PHOTOELASTIC EFFECT 

The photoelastic effect occurs in all states of matter and in particular in crystalline media belonging 
to all symmetry groups. The effect is described analytically by a fourth rank strain-optic tensor, p ijkl , 
which couples the strain tensor, S kl , to the indicatrix, (l/«%-, where n is the index of refraction. 10,11 
In particular, the change, A, in the indicatrix is directly proportional to the strain : 



'(-2) = t Pi. 

\ n / ij k,l=l 



ijkl ^kl ' 



0) 



The components of the strain optic tensor are dimensionless, since the indicatrix and strain are both 
dimensionless. Typically, the absolute value of the p components (which may be either positive or 
negative) range from 0.1 to 0.3 and the maximum value observed is less than 0.6. 

Since the strain and indicatrix tensors are symmetric tensors, Eq. (1) is unaffected by a change in 
order of the ij or the kl subscripts. It is therefore convenient to rewrite this equation in reduced notation 

A (A) = I PtjSjl »V/=1,2,...,6. (2) 

using the standard subscript contraction : 

Subscript Contracted Subscript 



11 


1 


22 


2 


33 


3 


23 and 32 


4 


13 and 31 


5 


12 and 21 


6 



478 



17 Elastooptical Materials 479 



TABLE 17-1. FORM OF THE STRAIN-OPTIC TENSOR 

(After Nye 10 ) 
KEY TO NOTATION 

• zero component 

• non-zero component 
• • equal components 

• o components numerically equal, but opposite in sign 

(•) a component equal to the heavy dot component to which it is joined 

(3) a component equal to minus the heavy dot component to which it is joined 

X i(Pn -Pi 2 ) 




CLASSES 
4,4,4/m 

XI..! 



TETRAGONAL 



CLASSES 
4mm , 42m ,422,4/mmm 



• • • 



X 



(10) 






TRIGONAL 



CLASSES 
3 m 1 32,3 m 




X>M8) 



CLASSES 
6,6, 6/m 



HEXAGONAL 



CLASSES 




6m 2, 6mm, 622, 6/m mm 

XI:. 



\ 



X/(8) 



X/(6) 



CLASSES 
23, m3 




CUBIC ^ CLASSES 

43 m,432, m 3m 




(3) 



SOTROPIC 




X/(2) 



480 Handbook of Lasers 

TABLE 17-1. FORM OF THE STRAIN-OPTIC TENSOR (Continued) 



TRICLINIC 
Both Classes 



(36) 



Diad || X 2 

(Standard 
Orientation 




MONOCLINIC 
All Classes 
Diad || x 3 



(20) 







(20) 




(12) 



In this form it is clear that the strain-optic tensor can be represented by a 6 x 6 array of components. 
In triclinic crystals all 36 components may be different. Fortunately for the experimentalist, in crystals 
of higher symmetry many of these components are related or known to be zero. 10 Table 17-1 summarizes 
the form of the strain-optic tensor for all the various crystal point groups as well as for isotropic materials 
such as glass. 

In crystals that are electro-optic (i.e., those that lack a center of symmetry) both an applied strain 
and an applied electric field, E k , can cause a change in the indicatrix. That is, 



v). 



: Li Pijkl $kl 
k,l = l 



+ L r 

k=l 



s rr 

ijk -£' 



'*> 



(3) 



where pf jkl is the strain-optic tensor component measured at constant electric field conditions and rf jk 
is the usual electro-optic coefficient measured at constant strain. The superscripts S and E are used to 
emphasize the conditions of measurement. These two effects are coupled together by the piezoelectric 
effect. For example, if only a strain wave is applied, piezoelectric coupling can produce an associated 
electric field that, due to the electro-optic effect, can either add or subtract from the primary photoelastic 
effect. The effective strain-optic coefficient in this case is 



\Pijkl)eff. — Pijkl ~~ 



2-,m,n=l r ijm e nkl ^m ™ n 



(4) 



V 3 f s N N 

where N is the unit normal to the acoustic wave front, e nkl is the piezoelectric tensor, and e£„ is the 
dielectric tensor measured at constant strain. 12 In ferroelectric materials such as crystalline lithium 
niobate, where the piezoelectric coupling is large, the electro-optic contribution is of the same order of 
magnitude as the primary photoelastic effect. 12 However, in most materials the piezoelectric effect is 
sufficiently small that the electro-optic contribution may be neglected. This is fortunate, because most 
of the photoelastic measurements made prior to 1968 did not consider or even recognize the electro- 
optic contribution. In fact, lithium niobate is the only material for which the primary photoelastic effect 
and electro-optic contribution have been completely determined. 12 

A compilation of reported and unpublished photo-elastic data is found in Table 17.2. 



17 Elastooptical Materials 481 
TABLE 17-2. PHOTOELASTIC PROPERTIES OF MATERIALS 

1. All data measured at room temperature. 

2. Typical accuracy of a good measurement of p i} is ±5%. 

3. If the sign of p i} is not specified, this implies only the absolute value is known. 

4. Acousto-optic figure of merit, M 2 , has been normalized relative to fused silica. To convert 
these relative values to absolute values, multiply by 1.51 x 10 -18 sec 3 /gm. 

5. Reported M 2 values are the maximum known. However, if all the strain-optic tensor com- 
ponents are not specified, it may be assumed that larger M 2 values may exist in the material. 

ISOTROPIC 



Material 



Wavelength 

A(/x) Pl1 



Pl2 



M 2 



Footnote 



Fused silica (Si0 2 ) 


0.63 


+0.121 


+0.270 


1.0 


1 


As 2 S 3 -glass 


1.15 


+0.308 


+0.299 


230 


1 


Dense flint (SF-4) 


0.63 


+0.232 


+0.256 


3.0 


1 


Water 


0.63 


0.31 


0.31 


106 


1 


Ge 3 3 Se 5 5 Asi 2 -glass 


1.06 


0.21 


0.21 


164 


2 


Sb 2 3 


0.63 






18 


3 


Various optical glasses 




0.09- 


0.18- 






(range of values) 


0.59 


0.24 


0.28 




4,5 


Dense flint 












(Schott SF-59) 


0.63 


0.27 


0.24 


12.5 


6 


PbO: 2Sb 2 3 


0.63 






18.5 


3 


Lucite 


0.63 


0.30 


0.28 


33 


7 


Polystyrene 


0.63 


0.30 


0.31 


84 


7 



CUBIC 

Classes 43m, 432, and m3m 



Material 



A(/u) 



Pn 



Pl2 



/>44 



M 2 



Footnote 



GaP 


0.63 


-0.151 


-0.082 


-0.074 


29.5 




GaAs 


1.15 


-0.165 


-0.140 


-0.072 


69. 




Y 3 A1 5 12 (YAG) 


0.63 


-0.029 


+0.009 


-0.061 


0.048 




Y 3 Fe s 12 (YIG) 


1.15 


0.025 


0.073 


0.041 


0.22 




/8-ZnS 


0.63 


+0.091 


-0.01 


+0.075 


2.3 




Ge 


10.6 


+0.27 


+0.235 


+0.125 


540 


8 


ZnAl 2 4 


0.63 


<0.009 


0.03 




0.005 


9 


SrTi0 3 


0.63 


0.15 


0.095 


0.072 


1.1 


10 


Y 3 Ga 5 12 


0.63 


0.091 


0.019 


0.079 


0.56 


10 


Bi 4 Ge 3 12 


0.63 








3.3 


11 


KRS-5 














(Thallium bromoiodide) 


0.63 








118. 


7 


Diamond 


0.59 


-0.31 


-0.03 






12 




0.59 


-0.43 


+0.19 


-0.16 




13 


LiF 


0.59 


+0.02 


+0.128 


-0.064 




14 


MgO 


0.59 


-0.32 


-0.08 






14 


KBr 


0.59 


+0.22 


+0.171 


-0.026 




14 


KC1 


0.59 


+0.17 


+0.124 






14 


KI 


0.59 


+0.210 


+0.169 






14 


NaCl 


0.59 


+0.110 


+ 0.153 


-0.010 




14 



1 . R. W. Dixon, " Photoelastic properties of selected materials and their relevance for applications to acoustic light modu- 
lators and scanners," /. App. Phys. 38, 5149-5153, 1967. 

2. J. T. Krause and D. A. Pinnow, unpublished data. 

3. D. A. Pinnow and D. B. Fraser, unpublished data. 

4. K. Vedam, " Elastic and photoelastic properties of some optical glasses," Proc. Indian. Acad. Sci., A31, 450-458, 1950. 

5. N. F. Borrelli and R. A. Miller, " Determination of the individual strain-optic coefficients of glass by an ultrasonic tech- 
nique," Appl. Optics, 7, 745-749, 1968. 

6. D. A. Pinnow and S. R. Williamson, unpublished data. 

7. T. M. Smith and A. Korpel, " Measurement of light-sound interaction efficiencies in solids," IEEE J. Quantum Elect. 
QE-1, 283-284, 1965. 

8. R. L. Abrams and D. A. Pinnow, "The acousto-optic properties of crystalline germanium," /. Appl. Phys., 41, 2765- 
2768, 1970. 

9. D. A. Pinnow and L. G. Van Uitert, unpublished data. 

10. J. Reintjes and M. B. Schulz, " Photoelastic constants of selected ultrasonic delay-line crystals," /. Appl. Phys. 39, 
5254-5258, 1968. 

11. D. A. Pinnow, S. R. Williamson, and A. A. Ballman, unpublished data. 

12. E. D. D. Schmidt, J. L. Kirk, and K. Vedam, " Variation of the refractive index of diamond with hydrostatic pressure 
to 7 kilobars," Am. Mineralogist, 53, 1404-1406, July-August 1968. 

13. G. N. Ramachandran, Proc. Ind. Acad. Sci. 32A, 171-173, 1950; and Proc. Ind. Acad. Sci., 25A, 208, 1957. 

14. E. Burstein, P. L. Smith, and B. Henvis, Phys. Rev., 73, 1262, 1948. 



482 Handbook of Lasers 

TABLE 17-2. PHOTOELASTIC PROPERTIES OF MATERIALS {Continued) 

CUBIC 

Classes 23 and m3 



Material 



Mi>) 



pn 



Pl2 



Pl3 



Pax 



M 2 



Footnote 



Ba(N0 3 ) 2 


0.63 


0.15 


0.35 


0.29 


0.02 


15. 


1 


Bi 12 GeO 20 


0.63 










6.6 


2 


B112S1O20 


0.63 










6.0 


2 


Pb(N0 3 ) 2 


0.63 










17. 


3 


NaBr0 3 


0.59 


0.185 


0.218 


0.213 


-0.0139 




4 


NaC10 3 


0.59 


0.162 


0.24 


0.20 


-0.198 




4 



TRIGONAL 

Classes 3m, 32, and 3m 



Material 



Afc) 



Pn 



P12 



Pl3 



PlA 



LiTa0 3 


0.63 


0.08 


0.08 


0.09 


0.03 


a-Al 2 3 


0.63 


0.20 


0.078 


~o 




Te 


10.6 


0.155 


0.130 






LiNb0 3 (p E ) 


0.63 


-0.02 


+0.08 


+0.13 


-0.08 


Ruby 












(Al 2 O 3 +0.05%Cr) 


0.63 


-0.23 


-0.03 


+0.02 


0.00 


a-Quartz (Si0 2 ) 


0.59 


+0.16 


+0.27 


+0.27 


-0.03 






+0.138 


+0.25 


+0.259 


-0.029 


CaC0 3 




+0.095 


+0.189 


+0.215 


-0.006 



Material 



/>31 



/>33 



Pa-i 



PaA 



M 2 



Footnote 



LiTa0 3 


0.09 


0.15 


0.02 


0.02 


0.91 


5 


a-Al 2 3 


~o 


0.252 




0.09 


0.22 


5 


Te 










2,920 


5 


LiNb0 3 (/> E ) 


+0.17 


+0.07 


-0.15 


+0.12 


9. 


6 


Ruby 














(Al 2 O 3 + 0.05%Cr) 


-0.04 


-0.20 


+0.01 


-0.10 




7 


a-Quartz (Si0 2 ) 


+0.29 


+0.10 


-0.047 


-0.079 




8 




+0.258 


+0.098 


-0.042 


-0.0685 




9 


CaC0 3 


+0.309 


+0.178 


+0.01 


-0.090 




10 






TRIGONAL 












Classes 3 and 3 









Material A(ju.) M 2 Footnote 



Li 2 W0 4 0.63 2.5 



11 



1. D. A. Pinnow, unpublished data. 

2. E. L. Venturing E. G. Spencer, and A. A. Ballman, " Elasto-optic properties of Bi 12 GeO 20 , Bi 12 SiO 20 and 
Sr^Bai^NbaOe,"/. Appl. Phys., 40, 1622-1624, 1969. 

3. T. M. Smith and A. Korpel, "Measurement of light-sound interaction efficiencies in solids," IEEE J. Quantum Elect. 
QE-1, 283-284, 1965. 

4. T. S. N. Murthy, Proc. Indian Acad. ScL, A40, 167, 1954. 

5. R. W. Dixon, " Photoelastic properties of selected materials and their relevance for applications to acoustic light modu- 
lators and scanners," /. Appl. Phys. 38, 5149-5153, 1967. 

6. G. A. Coquin, " Acousto-optic interactions in piezoelectric crystals," presented at the 1969 IEEE Ultrasonics Symposium, 
St. Louis, Mo. 

7. A. D. Franklin and H. S. Bennett, editors, "ARPA-NBS program of research on high temperature materials and laser 
materials," National Bureau of Standards Technical Note 514, January 1970. 

8. T. S. Narasimhamurty, "Photoelastic constants of a-quartz," J. Opt. Soc. Amer., 59, 682-685, 1969. 

9. F. Pockels, Ann. Phys. Chem {Leipzig), 37, 144, 1889. 

10. F. Pockels, Ann. Phys. {Leipzig), 11, 726, 1903. 

11. D. A. Pinnow, S. R. Williamson, and A. A. Ballman, unpublished data. 



Elastooptical Materials 483 
TABLE 17-2. PHOTOELASTIC PROPERTIES OF MATERIALS (Continued) 



HEXAGONAL 

Classes 6m2, 6mm, 622, and 6/mmm 


Material 


Mh) 


Pll Pl2 P31 />44 


M 2 


Footnote 


CdS 


0.63 


0.142 0.066 0.041 0.054 


8.0 


1 



HEXAGONAL 

Classes 6, 6, and 6/m 



Material 


AQi) 


/>n 


P31 


Pl6 


M 2 


Footnote 




LiI0 3 


0.63 


0.32 


0.41 


0.03 


8.3 


2 





TETRAGONAL 

Classes 4mm, 42m, 422, and 4/mmm 



Material 


M& 


Pn 


Pl2 


Pl3 


P31 


Ti0 2 (Rutile) 


0.63 


-0.011 


+0.172 


-0.168 


-0.096 


ADP (Ammonium dihydrogen 












phosphate) 


0.63 


+0.302 


+0.246 


+0.236 


+0.195 


KDP (Potassium 












dihydrogen phosphate) 


0.63 


+0.251 


+0.249 


+0.246 


+0.225 


ZrSiO* 


0.63 


0.06 




0.13 


0.07 


Te0 2 


0.63 


0.0074 


+0.187 


+0.340 


+0.090 


Sr .75Ba .25Nb 2 O 6 


0.63 


0.16 


0.10 


0.08 


0.11 


Sr . 5 Bao. 5 Nb 2 6 


0.63 


0.06 


0.08 


0.17 


0.09 


Material 


P33 


/>44 


/>6 6 


M 2 


Footnote 


Ti0 2 (Rutile) 


-0.058 






2.6 


1,3 


ADP (Ammonium dihydrogen 












phosphate) 


+0.263 




0.075 


4.2 


1,3 


KDP (Potassium dihydrogen 












phosphate) 


+0.221 




0.058 


2.5 


1,3 


ZrSiO* 


0.09 




0.10 


2.4 


A 


Te0 2 


+0.240 


-0.17 


-0.046 


525. 


5 


Sr .75Bao. 25 Nb 2 6 


0.47 






26. 


6 


Sr . 5 Bao. 5 Nb 2 6 


0.23 






5.8 


6 



1. R. W. Dixon, " Photoelastic properties of selected materials and their relevance for applications to acoustic light modu- 
lators and scanners," /. App. Phys. 38, 5149-5153, 1967. 

2. A. W. Warner, D. A. Pinnow, J. G. Bergman, Jr., and G. R. Crane, " Piezoelectric and photoelastic properties of lithium 
lodate," /. Acoust. Soc. Amer., 47, 791-794, March 1970. 

3. T. A. Davis and K. Vedam, "Pressure dependence of the refractive indices of the tetragonal crystals: ADP KDP 
CaMo0 4 , CaW0 4 , and rutile," /. Opt. Soc. Amer. 58, 1446-1451, 1968. 

4. D. A. Pinnow, unpublished data. 

5. N. Uchida and Y. Ohmachi, " Elastic and photoelastic properties of Te0 2 single crystals," /. Appl. Phys., 40, 4692-4695, 

6. E. L. Venturini, E. G. Spencer, and A. A. Ballman, " Elasto-optic properties of Bi 12 Ge0 20 , Bi,,Si02n and 
Si^&y.^^O^ J. Appl. Phys., 40, 1622-1624, 1969. ° 



484 Handbook of Lasers 

TABLE 17-2. PHOTOELASTIC PROPERTIES OF MATERIALS {Continued) 



TETRAGONAL 

Classes 4, 4, and 4/m 


Material 


AQ*) 


Pn 


Pl2 Pl3 P31 


P33 


M 2 


Footnote 




PbMoO* 
CdMo0 4 
PbW0 4 


0.63 
0.63 


0.24 
0.12 


0.24 0.255 0.15 
0.10 0.13 0.11 


0.29 

0.18 


23.7 

4.5 

21.0 


1 

2 
3 




ORTHORHOMBIC 

All Classes 


Material A([m) 


i 


Pn 


Pl2 Pl3 


P21 


P22 


P23 


P31 



(I-HIO3 


0.63 


0.406 


0.277 


0.304 


0.279 


0.343 


0.305 


0.50: 


Ca(Nb0 3 ) 2 


0.63 
















PbC0 3 


0.63 


0.15 


0.12 


0.16 


0.05 


0.06 


0.21 


0.14 


Ba 2 NaNb 5 15 
















0.17 


BaS0 4 


0.59 


+0.21 


+0.25 


+0.16 


+0.34 


+0.24 


+0.19 


+0.27 



Material 



P32 



P33 



Pa* 



Pss 



P66 



M 2 



Footnote 



a-HI0 3 


0.310 


0.334 


Ca(Nb0 3 ) 2 






PbC0 3 


0.16 


0.12 


Ba 2 NaNb 5 15 






BaSO* 


+0.22 


+0.31 



+0.002 



-0.012 



0.092 



+0.037 



55. 


4 


1.3 


5 


15. 


6 


5.-10. 


7 




8 



MONOCLINIC 

All Classes 


Material 


A(/x.) M 2 Footnote 


Pb 2 MoO s 


0.63 27. 3 



1. D. A. Pinnow, L. G. Van Uitert, A. W. Warner, and W. A. Bonner, "Lead molybdate: a melt-grown crystal with a high 
figure of merit for acousto-optic device applications," Appl. Phys. Lett., 15, 83-86, 1969. 

2. D. P. Schinke and W. Viehmann, unpublished data. 

3. D. A. Pinnow and L. G. Van Uitert, unpublished data. 

4. D. A. Pinnow and R. W. Dixon, " Alpha-iodic acid : a solution-grown crystal with a high figure of merit for acousto-optic 
device applications," Appl. Phys. Lett., 13, 156-158, 1968. 

5. D. A. Pinnow, S. R. Williamson, and A. A. Ballman, unpublished data. 

6. D. A. Pinnow and S. R. Williamson, unpublished data. 

7. E. G. Spencer and L. G. Van Uitert, "Elastic properties of Ba 2 NaNb 5 Oi 2 ," Phys. Lett. 27 A, 626-627, 1968. 

8. K. Vedam, Proc. Indian Acad. Sci. A34, 161, 1951. 



ACOUSTO-OPTIC MATERIALS 

The acousto-optic interaction has been treated in depth by several authors 1 ' 13 " 17 to whom the reader 
is referred. In order to establish requirements for acousto-optic materials the operation of a rudimen- 
tary light beam deflecting device is reviewed here. This device is representative of acousto-optic devices 
in general and has the geometry shown in Fig. 17-1. A traveling acoustic wave is launched into the 
deflector when the piezoelectric transducer is electrically excited. The dimensions of the flat rectangular 
transducer H and L are those of the acoustic beam waist. In most cases, the acoustic wavelength is much 
smaller than H and L, so that the acoustic beam is well collimated as it propagates away from the 
transducer and intercepts the light beam, which for generality has been taken to have an elliptical 



17 Elastooptical Materials 485 



TRANSDUCER 




">- 



Fig. 17-1. Simple light beam deflector. A portion of the incident light beam is deflected by angle <f> after passing 
through the region of material in which ultrasonic wave exists. The ultrasonic wave originates at the transducer and pro- 
pagates in the X direction. Power in the ultrasonic wave decreases exponentially as a function of distance from the trans- 
ducer, due to acoustic loss. 



cross section. In the usual Bragg limit, one finds that the fraction I/I of the incident light intensity that 
is deflected is related to the amplitude A# of the acoustically established optical phase grating by 



— = sin 

In 



Acf) 



The amplitude A</> is 



A<t> 



"V?® 



M 2 P a 



(5) 



(6) 



where X is the optical wavelength, P ac is the acoustic power, and M 2 is a group of material parameters 
known as the acousto-optic figure of merit. It is apparent from Eqs. (5) and (6) that as P ac increases A</> 
also increases, and that in principle any fraction of the incident light beam, up to 100 percent, may be 
deflected. A useful approximation relating acoustic power to the fractional deflection efficiency, rj, is 
given by 



( atn*77^ l - i m \ 2 

lW S) ~ \Lj M 2 (relative to fused silica) \0.633/ *' 



(7) 



which holds for r\ < 0.7. In this expression the figure of merit is expressed relative to that of fused silica, 
a common reference material. Equation (7) emphasizes that the acoustic power required to deflect a 
given fraction of a light beam decreases with increasing figures of merit, but increases with increasing 
wavelength. As an example, if fused silica were chosen as the acousto-optic medium (M 2 = 1) and the 
aspect ratio H/L of the acoustic beam waist were chosen to have a typical value of unity, then 38.5 wattsof 
acoustic power would be required to deflect 50% (rj = 0.5) of a He-Ne laser beam (A = 0.633/*). The 
reason for selecting a material with a higher figure of merit than fused silica is simply to reduce the drive 
power. 

The figure of merit is a combination of well-known material properties : 



M 2 = n 6 p 2 fpV 3 , 



(8) 



where n is the index of refraction, p the strain-optic component, p the density, and V the acoustic 
velocity. It should be noted that n, p, and V are all related to tensor quantities and therefore vary with 
crystal orientation. A crystal cut that maximizes the figure of merit is, of course, chosen for a device 
application. 



486 



Handbook of Lasers 



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488 Handbook of Lasers 

Frequently one finds several modified expressions for the figure of merit in the literature. 18 Al- 
though M 2 is a directly measured quantity in the techniques developed by Dixon and Cohen 19 and 
Smith and Korpel, 20 two alternate expressions 



M t s 



n'p 2 



pV 
and (9) 



M % = 



[ 3 



pV 2 



are applicable to particular device designs where constraints placed upon device geometry relate to 
material properties. 16 

A high figure of merit is desirable, though not sufficient, for a material to be suitable for device 
applications. In addition, the material must have low optical and acoustic losses in its intended opera- 
ting range and must be available in high optical quality. Other desirable features are good mechanical 
properties and low cost. There is no single material that is the best choice for all applications. Table 17-3 
summarizes those materials that have one or more superior properties, which make them the preferred 
choice for device applications. Additional data on the figure of merit of other materials is included in 
Table 17-2. 



REFERENCES 

1. E. I. Gordon, "A review of acousto-optical defection and modulation devices," Proc. IEEE, 54, 1391-1401, 1966. 

2. D. Maydan, "Acousto-optical pulse modulators," IEEE J. Quant. Electronics, QE-6, 15-24, 1970. 

3. M. B. Schulz, M. G. Holland, and L. Davis, Jr., " Optical pulse compression using Bragg scattering by ultrasonic waves," 
Appl. Phys. Lett. 11, 237-240, 1967. 

4. J. H. Collins, E. G. H. Lean, and H. J. Shaw, "Pulse compression by Bragg diffraction of light with micro-wave sound," 
Appl. Phys. Lett. 11, 240-242, 1967. 

5. M. P. Wenkoff and M. Katchky, " An improved read-in technique for optical delay line correlators," Appl. Optics, 9, 135-147, 
January 1970. 

6. S. E. Harris and R. W. Wallace, " Acousto-optic tunable filter," /. Opt. Soc. Am. 59, 744-747, 1969. 

7. A. Korpel, R. Adler, P. Desmares, and W. Watson, " A television display using acoustic deflection and modulation of coherent 
light," Proc. IEEE, 54, 1429-1437, 1966. 

8. D. A. Pinnow, L. G. Van Uitert, A. Warner, and W. A. Bonner, "Lead molybdate: a melt-grown crystal with a high figure 
of merit for acousto-optic device applications," Appl. Phys. Lett. 15, 83-86, 1969. 

9. N. Uchida and Y. Ohmachi, "Acousto-optical light deflection using Te0 2 single crystal," Jap. J. Appl. Phys. 9, 155-156, 
1970. 

10. J. F. Nye, " Physical Properties of Crystals," Oxford : Clarendon Press, 1967, pp. 243-257. 

11. W. P. Mason, "Crystal Physics of Interaction Processes," New York: Academic Press, 1966, pp. 165-183. 

12. G. A. Coquin, "Acousto-optic interactions in piezoelectric crystals," presented at the 1969 IEEE Ultrasonics Symp., St. Louis, 
Mo. 

13. C. F. Quate, C. D. W. Wilkinson, and D. K. Winslow, "Interaction of light and microwave sound," Proc. IEEE, 53, 1604-1623, 
1965. 

14. W. R. Klein and B. D. Cook, " Unified approach to ultrasonic light diffraction," IEEE Trans. Sonics and Ultrasonics, SU-14, 
123-134, July 1967. 

15. R. Adler, "Interaction between light and sound," IEEE Spectrum, 4, 42-54, May 1967. 

16. D. A. Pinnow, "Guidelines for the selection of acousto-optic materials," IEEE J. Quant. Electronics, QE-6, ll'i-l'il, 1970. 

17. G. A. Coquin, J. P. Griffin, and L. K. Anderson, "Wideband acousto-optic deflectors using acoustic beam steering," IEEE 
Trans. Sonics and Ultrasonics, SU-17, 34-40, January, 1970. 

18. R. W. Dixon, " Photoelastic properties of selected materials and their relevance for applications to acoustic light modulators 
and scanners," /. Appl. Phys., 38, 5149-5153, 1967. 

19. R. W. Dixon and M. G. Cohen, "A new technique for measuring magnitudes of photoelastic tensors and its application to 
lithium niobate," Appl. Phys. Lett. 8, 205-206, 1966. 

20. T. M. Smith and A. Korpel, " Measurement of light-sound interaction efficiencies in solids," IEEE J. Quant. Electronics, QE-1. 
283-284, 1965. 



Non-Linear Optical Materials 

S. Singh 

Bell Telephone Laboratories 
Murray Hill, New Jersey 07974 

INTRODUCTION 

When a material substance is subjected to electromagnetic radiation the electrons of the medium 
tend to be polarized. For small values of the electric field E associated with the radiation, the induced 
polarization 0* or the electric dipole moment per unit volume of the medium is linear in the field, i.e., 

&> = e oX {i) -E, (1) 

where x (1) is the linear optical susceptibility of the medium and e is the permittivity of free space and 
has the value of 8.85 x 10~ 12 C 2 • sec 2 /kg • m 3 . (The mks system of units is used in this chapter.) The 
linear polarization assumed in Eq. (1) is responsible for the familiar linear optical phenomena of 
reflection and refraction. The linear susceptibility x (1) is related to the index of refraction, n, of the 
medium by 

X (1) =" 2 -l. (2) 

For large values of the optical electric field, such as those available from the laser sources, the induced 
optical polarization can be represented as a series expansion 

9 = £ [/ (1) • E + X (2) • E 2 + * (3) • £ 3 + . . .], (3) 

where x (2 \ Z (3) > etc. are the non-linear optical susceptibilities of the medium and are responsible for a 
large variety of non-linear optical phenomena. Most of the interesting non-linear effects arise from the 
terms of electric polarization that are quadratic or cubic functions of the electric field amplitudes. The 
quadratic polarization gives rise to the phenomena of second harmonic generation (SHG), 1 d.c. recti- 
fication, 2 linear electro-optic (EO) or Pockel's effect, 3 and parametric generation (PG). 4 The effects 
arising from the cubic polarization term are third harmonic generation (THG), 5 quadratic electro-optic 
or Kerr effect, 3 two photon absorption, 6 and stimulated Raman, 7 Brillouin, 8 and Rayleigh 9 scattering. 
Good review articles on the subject of non-linear optical effects can be found in references 3, 10, 11, 12, 
13, 14 and 15. 

SECOND ORDER POLARIZATION AND ITS SYMMETRY 
PROPERTIES 

In this chapter we consider only the lowest order non-linear susceptibility of crystalline media. For 
the general case of two light waves of angular frequencies (o t and co 2 incident upon such a medium, the 
rth Cartesian component of the induced second order polarization & at the sum or difference frequencies 
co ± ± co 2 can be written as 

0>{<oi±*2) = ( g = 2 )e £ d\j k <0l±<02 ' <0i ' ±{0l) -Ef ,l) 'Ei ±0>2 \ (4) 

j,k= 1,2, 3 

where d iJk is the non-linear optical coefficient of the medium and £, and E k are the electric field ampli- 
tudes (actually the spatially dependent Fourier amplitude) associated with the two waves. The degeneracy 
constant g arises from the number of distinguishable permutations of the frequencies. 

489 



490 



Handbook of Lasers 



For the specific case of SHG, w 1 = co 2 = co andg = 1, the second order polarization at the harmonic 
frequency is given by 



i2a> 



= eo 



j(-2<d,o, to) . p(o>) . p(<o) 



j,k= 1,2,3 



Hjk 



(5) 



The SHG coefficient dig is a (3 x 3 x 3) third rank tensor. Since the order in which the two electric 
field components are written in the right hand side of Eq. (5) is of no significance, the SHG coefficients 
satisfy the permutation symmetry 16 dig = d£f. This property is similar to that of the piezoelectric 
tensor (by virtue of which an electric polarization is produced in a medium when it is subjected to a 
stress). By analogy with the piezoelectric tensor, it is possible to write for convenience the non-linear 
optical tensor dig in a contracted form in which the symmetric suffixes j and k are replaced by a single 
suffix / that takes the values 1 to 6. The relation between / and ./ft is 

jk I 

11<->1 

22<->2 

33<->3 (6) 

23 or 32^4 
31 or 13<->5 
12 or 21<->6 

In the contracted form the d t 's are 18 in number and the components of the second order polariza- 
tion at the harmonic frequency of 2co can be written in the matrix form. 

^ii ^12 d l3 d i4 d 15 d l6 \ 



= e 



"21 "22 "23 "24 "25 "26 

i^3i ^32 ^33 d 34 d 35 d 36 2E xE 



2E y E z 



(7) 



2E x E y 



The number of non- vanishing, independent elements of the second harmonic tensor depends upon 
the point group symmetry of the medium. (For the procedure to obtain the number of non- vanishing 
elements of a third rank tensor subjected to the point group symmetry of a crystal, see Ref. 17 and 18.) 
Since the non-linear tensor dig is a polar tensor of odd rank, its elements are identically zero for any 
medium possessing a center of inversion. For the 21 out of 32 crystal classes that lack a center of inver- 
sion, the contracted form of the second harmonic tensor is given in Table 18-1. For the choice of the 
non-linear optic axes x, y, and z we follow the IRE convention. 19 

TABLE 18-1. FORM OF THE SHG-TENSOR FOR THE VARIOUS CRYSTAL 

CLASSES 

TRICL1N1C SYSTEM 



Class 1—d 



MONOCLINIC SYSTEM 



d 3 i 



d 2 i 




rfi: 
d 2 : 
d 3 ; 



di2 

d 2 2 





d 22 
d 3i 



du 
d 2A 
dzt 



Class m-^C. 



d 13 

d 23 





d lt 
d 2i 
d 3! 



d u 
d 2< 
d 3t 



m±_ z 



18 Non-Linear Optical Materials 491 

TABLE 18-1. FORM OF THE SHG-TENSOR FOR THE VARIOUS CRYSTAL 

CLASSES (Continued) 



Class m — C s 




d 31 







d 31 





d 2l 




ORTHORHOMBIC SYSTEM 



TETRAGONAL SYSTEM 



TRIGONAL SYSTEM 







d 31 






d 3 l 



d 12 



d 32 



di3 



d 33 











d 15 



d 35 



Class 2 — C 2 



d 14 . d 15 

d 24 d 2S 





Class 2 — C 2 





d 23 




d 14 



d 34 



Class mm2 — C 2v 











d 32 d 33 

Class 222— D 2 



d i5 









d 3 i 



d 1A 







d 2S 




d 1( 



d 3( 



Class 4—Ca. 



d 14 

d ls 









d 3 i —d 31 



Class 4 — £4. 

dt* 
-d 15 




d ls 

—d 14 





d 15 

diA 





Class 4mm — C 4 » 





d 15 




d 15 





C/aw 42m — D 2i 



dtA 







<*14 









d 3 6 



Class 422— D 4 



di4 







diA 




( 



Class 3—C 3 



m± Y 
(IRE-convention) 



2IIZ 



2\\Y 
(IRE-convention) 



du —d lt 

— «22 «22 

^31 ^31 



diA 

d 15 





^15 — d 22 
—diA —d lt 




Class 3m — C 3v 



(0 d 15 -d 22 \ 

-d 22 d 22 d 15 

rf 3 i rf 3 i rf 33 0/ 



m±X 
(IRE-convention) 



492 



Handbook of Lasers 



TABLE 18-1. FORM OF THE SHG-TENSOR FOR THE VARIOUS CRYSTAL 

CLASSES {Continued) 



HEXAGONAL SYSTEM 



CUBIC SYSTEM 



Class 3m — C 3 





d 3 l 




d$i 



d lt 







d 15 












-d 1} 





m±_ Y 



Class 32— D 3 



d 14 





-d 14 . —du 



Class 6 — C 3h 



du 
—d%2 




d 22 




-d 22 
-d lt 




Class 6—C 6 







d 3 i 







d 3i 



di4 

d ls 





d 15 

-d l4 





Same as Class 4 — C 4 
Class 6m2 — D 3h 





-d 2 2 













-d 2 , 





Class 6m2 — D 3h 



-d tl 







-du 




mLX 
(IRE-convention) 



mi y 



C/om 6mm — C 6v 







d 3i 






^31 





d ls 









Same as Class 4mm — C 4o 
Class 622— D 6 



d 14 , 
-d 14 




Same as Class 422 — D* 



Class 23— T 



d 14 







d 14 




Class 43m— T d 












du 



Class 432— O 
All elements vanish. 



18 Non-Linear Optical Materials 493 

In certain cases, the number of non-vanishing elements of the non-linear optical tensor is further 
reduced by an additional symmetry condition, 20 if it is assumed that the optical frequencies involved lie 
far enough removed from the characteristic ultraviolet and infrared absorption bands of the medium. 
The dispersive effects can then be neglected and the non-linear optical tensor becomes independent of 
the frequencies and should become symmetric for the interchange of any two suffixes in d$. As a 
result of this symmetry the following equalities are obtained: 

d l2 = d 26 » d 13 = d 35 , d l4 . = d 2S = d 36 ,d l5 = d 3l , 

die = d 2 i > d 23 = d 24 . and d 24 = d 32 . 

SECOND HARMONIC POWER AND COHERENCE LENGTH 

The second harmonic power p 2m generated by a single mode Gaussian beam of angular frequency 
co and power p" incident along a principal axis of a plane parallel slab of thickness L of a nonabsorbing 
nonlinear crystal is given by 

2m _ W'W'W-dS-OT'-g . r sin(LAX/2)- | 2 
P ~ ttw 2 • n 2< ° ■ (n<°) 2 L (LAK/2) J ' 



where 



w = spot radius of the fundamental beam 

ri° = refractive index of the crystal at the fundamental wavelength 
n 2 <° = refractive index of the crystal at the second harmonic wavelength 

d n = pertinent SHG coefficient 

H = permeability of free space 

e = permittivity of free space 
AK = (2K 10 - K 2t0 ), the wave vector mismatch between the bound and free harmonic waves in the 

crystal, 

and the powers p m and p 2(0 are both internal to the crystal. 

In general, because of dispersion in the medium, AA # and the bracketed term in the right of Eq. 
(8) indicates that the second harmonic power undergoes periodic oscillations, known as Maker 21 
oscillations, as a function of thickness, the period of the oscillation being given by / coh = n/AK, which 
is known as the " coherence length." For normal incidence the coherence length is given by 

/ = Al (9) 

coh 4(n 2(O -n 0> y 

where X x is the free-space wavelength of the fundamental wave. In an anisotropic medium, since rf and 
n 2( ° depend upon the electric polarization direction of the fundamental and second harmonic waves 
respectively, it follows from Eq. (9) that in such media, each non-linear optical coefficient has a coherence 
length associated with it. 

PHASE-MATCHED SECOND HARMONIC GENERATION 

It follows from Eq. (8) that for efficient second harmonic conversion, the wave vector mismatch A# 
between the interacting waves should be zero. This is termed phase matching. Because of the dispersion 
of the refractive index between the fundamental and second harmonic wavelengths, phase matching is 
difficult to achieve in an isotropic crystal. However, it was shown independently by Giordmaine 22 and 
Maker et al. 21 that, in an anisotropic crystal it is often possible to obtain AA: = by a suitable choice of 
direction of propagation and polarization. Depending upon the choice of polarization, two types of 
phase matching in birefringent crystals are possible. SHG with fundamental waves of parallel polari- 
zation is termed type I, and with orthogonal polarization type II. 



494 Handbook of Lasers 

PHASE MATCHING IN UNIAXIAL CRYSTALS 

For a beam propagating in a uniaxial crystal so that the wave normal of the beam makes an angle 
m with the optic axis of the crystal, the refractive index is given by the equation 

1 cos 2 m sin 2 fl„ 

[n{B m )f- n\ + nl ' (10) 

where n and n e are the ordinary and extraordinary refractive indices respectively. 
In a negative (n e < n ) uniaxial crystal the index matching conditions are, 

fortypel:n 2 <»(0 m ) = <> (11) 

for type II : n 2 <°(6 J = i[«<°(0 m ) + «-]. (12) 

For positive (n e > n ) uniaxial crystals, index matching requires 

fortypeI:nl (O =n°>(0 m ) (13) 

for type II : n 2o > = W(0J + <]. (14) 

By combining Eq. (13) and (14) each with Eq. (10), the phase matching angles m (I) and m (II) for a 
positive uniaxial crystal are given by 

" W (n?)- 2 -«)- 2 (15) 

Sln «°>- (<K f _ ! • (1« 

The phase matching angles for a negative uniaxial crystal can be similarly obtained by combining Eqs. 
(11) and (12) each with Eq. (10). 

PHASE MATCHING IN BIAXIAL CRYSTALS 

For a wave propagating in a biaxial crystal at angles and <f> with respect to the principal axes z 
and x respectively, the refractive index is given by Fresnel's equation 

sin 2 cos 2 6 sin 2 sin 2 <b cos 2 

= 2+ ,.v2 ,..v-2 + ^-2 ,..x-2 =0 > (17) 



(n)" 2 - (n x y 2 (n)- 2 - («„)- 2 T (»)" 2 - („J 

where «*, « y and « z are the principal indices of refraction. Hobden 23 has computed the possible loci 
0(0) of directions for both type I and type II phase matching in biaxial crystals. (For the stereographic 
projections and refractive index conditions for these loci, see Fig. 3 and Table I of Ref. 23). 

When the wave propagation is confined within one of the principal planes zx or zy, in which case 
4> = 0° or </> = 90° respectively, then Eq. (17) is greatly simplified. The phase matching angle m is then 
easily calculated by combining the appropriate index matching condition with Eq. (17). For example, 
for a wave propagating in the principal plane zx of a negative biaxial crystal, the phase matching angles 
m (I) and m (II) for type I and type II processes respectively are given by, 24,25 

(n m Y 2 — (n 2m V 2 

■fr'^- o^"-^" (18) 

and 

In order to obtain the corresponding phase matching angles for a wave propagating in the zy-plane, 
n x and n y are interchanged in Eqs. (18) and (19). 



18 Non-Linear Optical Materials 495 

SECOND HARMONIC CONVERSION EFFICIENCY FOR 
CRITICAL PHASE MATCHING 

When phase matched SHG is achieved by propagating the fundamental along a direction different 
from a principal axis of a birefringent crystal, it is termed critical phase matching (CPM). With a 
focused fundamental beam, the second harmonic conversion efficiency of the crystal is limited by the 
effects of double refraction and beam divergence. 26-28 These limitations can be described 28 in terms of 
a focusing parameter 

f =LV27OT*wg ( 2 °) 

and a double-refraction parameter 

B = pCnLn* /!^) 1 ' 2 , (21) 

where p is the double refraction angle and the other quantities have been defined above. For the beams 
propagating in a principal plane, p can be obtained from the relation 29,30 

l(n /n e ) 2 - l]tan fl„ 
l+("o/>O 2 tan 2 0„ 

The optimum phase matched second harmonic power/? 210 inside a non-linear material of thickness L due 
to its effective non-linear optical coefficient (d n ) eff * s given by 28 

p 2 °> = C • (jO 2 ■L-K° > -h m - exp[(-a w + a 2 72)L], (23) 

where 

„ 2Qi ) 3 ' 2 ( eo ) 1 ' 2 co 2 (4,) 2 ff 

C ~ nn 2 °>-(n*) 2 K ' 

k m = 2n/A u wave vector of the fundamental and h m is a function containing B and £. The function h m is 
conveniently plotted as a function of the focusing parameter £ for several values of B in Figure 2 of 
Ref. 28. For a given beam radius w it is often convenient to define an aperture length 30 



WoWe) - JJtan u m . 

tan P = , . r.. ,.. N2 + n „2 n ■ ( 2Z > 



and an effective length of the focus 2 



#-^ (25) 



l,~=f-. (26) 



Then, in limiting cases the asymptotic form of Eq. (23), neglecting absorption is 28 

L 2 for (l a , l f >L) (27) 

Ll a foi(l f >L>l a ) (28) 

p 2<o = 9^t.h f l a fot{L>l f >lJ (29) 

41} for (L>l a > I f ) (30) 

4.75/^ fot(l a >L>l f ) (31) 

SECOND HARMONIC CONVERSION EFFICIENCY FOR 
NON-CRITICAL PHASE MATCHING 

Phase matched SHG for 9 m = 90° is termed noncritical phase matching (NCPM). In this case, the 
walk-off angle p = 0, i.e., the direction of energy flow (Poynting vector) of the fundamental and second 
harmonic beams, is collinear. The second harmonic generated by an unfocused beam is then approxi- 
mated by Eq. (27). For optimizing 90° phase matching with a focused beam, the curve for B = in 



496 Handbook of Lasers 

Figure 2 of Ref. 28 is used, from which it is found that £ = 2.84 and h m = 1.068. Using these values in 
Eq. (23), the optimum second harmonic power is given by 

p 2(0 = (1.068)C(i> to ) 2 •LK'°' exp[(- <x m + a m /2)L]. (32) 

A convenient method 32,24 of obtaining NCPM consists of adjusting the temperature of the non- 
linear crystal to an appropriate value T m , at which the refractive index of the fundamental equals that 
of the second harmonic. The phase matching temperature is given by the equation 

.-co j.20) 

Tm = To + dn 2 °> dn" (33) 



dT dT 
where T is the room temperature. 

MEASUREMENT OF SHG-COEFFICIENTS 

The two most commonly employed methods of measuring SHG-coefficients are: 

1. Phase-matched SHG technique, 33 " 36 in which both cw and pulsed lasers have been used. All 
absolute measurements of SHG coefficients reported so far have been made using this technique. Since 
this method is limited to phase-matchable coefficients only, it can not always be used to determine all 
of the non-vanishing elements of the SHG tensor of a given crystal class. 

2. Maker oscillations technique 21 provides a simple way to determine both the magnitude and 
sign 24,37-39 of all non-zero elements of the SHG tensor of a crystal. Although, in principle a cw laser 
can be used, only pulsed and Q-switched lasers have been used. A majority of SHG-coefficients reported 
have been obtained by this technique. 

3. Other techniques that have been used to determine SHG-coefficients of single crystals are those 
utilizing reflection, 40,41 parametric fluorescence, 42,43 and the wedge technique. 

THEORETICAL ESTIMATE OF THE SHG COEFFICIENTS 

Optical non-linearities have an electronic origin. In the electric dipole approximation, only the 
valence electrons contribute to the second order non-linear susceptibility. The magnitude of the non- 
linear coefficient depends upon the distortion of the electronic wave functions and the asymmetry of the 
electronic clouds. The experimentally observed values of the SHG coefficients shown in Table 18-2, 
vary by four orders of magnitude among the various materials. 

It was suggested by Miller 44 that if electric polarizations instead of electric fields are used as the 
independent variables to describe SHG, then the second order non-linear coefficient df£ can De expres- 
sed in terms of the linear optical susceptibility xtj (defined in Eq. (3)) and a new third rank tensor d 2 $ 
(called Miller-<5) by the relation 

dijk = £o £ Xil°X%iXkn^lmn' (34) 

l,m,n 

For crystals with symmetry other than triclinic or monoclinic, Eq. (34) can be rewritten in the principal 
axis coordinate system of the x 2co -tensor as 

df^eoXlrxJiXtk-SlZ' ( 35 > 

The data in Table 18-2 show that the variation in the elements of df$ from one material to another is 
generally less than that exhibited by the corresponding d ijk \. Thus, if in the empirical relation Eq. (35), 
<5?£ is taken to be a constant with a value «0.07 m 2 /C for all materials, then an order of magnitude 
estimate of d$ for any material can be obtained from its refractive index data. 

In principle, it is possible to calculate the magnitude of the non-linear optical coefficients from 
general expressions, which may be derived 11,16 ' 45 " 48 by using the standard time-dependent perturba- 
tion technique of quantum mechanics. In practice, however, it is a difficult task because, in order to 
calculate the coefficients from these expressions, it is necessary to know the electron wave functions 



18 Non-Linear Optical Materials 497 



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6000*0 0O 



*--H 

-Hos os o 

•* od oo r-^ 

CO -«t ■* £h 



tj'Q'^ 



g 

«0 



s 



s 
*o 




co >* 

VO v© 



co 

00 00 00 00 ^ , 

in <o «r> >r> os 

o vo o vo oovo vq 

>-H © '-H©' rtrtO © 



© © « 

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OS VO *-i 

<s cs ■* 



os 
vo 



■* 


os 


T-H 


Os co 


o 


~ ^ 


23 


?2 


<s vo 


<s © 


cs r- 


to ir> 



■rt to 



-H-H -H-H 

t-^ co vo vo 

HOO Tf © 

co f- CS CO 



tSTS tt "W 



VO «o 
vo«lco 

I I OS CO 

J -H-H 

vn VO »-H 



5 



s 

A 

«0 



I 
CO 
CS 









•a 



*> S "^ 



3 

co CO 

SN 



.IS 

NN 



P Ul 

'•3'S 
3* 



"•3^ 

&£ 



506 Handbook of Lasers 

TABLE 18-3. SIGNS OF SECOND HARMONIC COEFFICIENTS 



Material d\ i 


d 14 . 


d 22 d 31 


d 3 2 


^33 


References 


1. Barium sodium niobate 










72 


2. Barium titanate 











70 


3. Beryllium oxide 











51,72 


4. Cadmium selenide 




± 




=F 


72 


5. Cadmium sulfide 








+ 


70 


6. Cadmium telluride 


_ 








72 


7. Cuprous chloride 


+ 








74 


8. Gadolinium molybdate 







+ 


_ 


72 


9. Gallium antimonide 


+ 








119 


10. Gallium arsenide 


+ 








119 


11. Gallium phosphide 


+ 








78, 119 


12. Indium arsenide 


+ 








119 


13. Lead niobate 




± 


± 


± 


98 


14. Lead titanate 




T 




± 


94 


15. Lithium formate monohydrate 






- 


+ 


72 


16. Lithium gallate 




_ 


+ 




70 


17. Lithium iodate 









_ 


50,72 


18. Lithium niobate 




+ - 




_ 


8,70 


19. Lithium tantalate 




+ - 






70 


20. Potassium dihydrogen phosphate 


+ 








80 


21. Quartz (1) + 










72 


22. Silicon carbide (h) 




=F 




± 


89 


23. Sodium nitrite 




T 


± 




120 


24. Terbium molybdate 






+ 





72,73 


25. Zinc oxide 




+ 




— 


70 


26. Zinc selenide (z) 


+ 








72 


27. Zinc sulfide (z) 


+ 








74 


28. Zinc sulfide (h) 









+ 


74 


29. Zinc telluride 


+ 








72 



very accurately— a condition which is rarely fulfilled. When approximate ground state wave functions 
are used for some covalent materials, rough agreement is obtained between the calculated and experi- 
mentally observed magnitudes of the SHG coefficients. 49-51 

A crude theoretical estimate of <5g can be made 52 by using a simple but highly qualitative and 
phenomenological model 11 of a classical anharmonic oscillator. Discussions of several other models 
that have been used for calculating the nonlinear optical coefficients can be found in references 53, 54, 
55 and 56. For a review of the various theoretical models for calculating the second order non-linear 
optical coefficients of solids, see reference 57. 

TABLES OF SHG COEFFICIENTS 

In Table 1 8-2 are listed the SHG coefficients dl m and dff in the mks units of m/V and m 2 /C respec- 
tively for a variety of crystals. Since in the literature both cgs and mks units are used, the following con- 
version relations can be used. 

47T 

^(mks) = — x 10" 4 • <#°(cgs, esu) 

3 (36) 

^"(mks) = — x 10 5 • ^"(cgs, esu) 

47T 



18 Non-Linear Optical Materials 507 

In the publications that use the cgs-system the second harmonic polarization is denned as 

&t m = Z tfjk' "' m ' E 1' E R (37) 

jk=l,2,3 

and the units of SHG-coemcients are expressed as simply esu. 

Data have been compiled from the literature through 1970. In addition, many unpublished results 
of the author and many of his colleagues have been included. Also listed in the Table are the funda- 
mental wavelengths X t , the refractive indices n<° and n 2<0 and, wherever possible, the phase matching 

angle 9 m . 

With regard to the convention for the absolute signs 58 Of SHG coefficients for the III-V and II-VI 
crystals, the outward normal from the metal ^-face (element II or III face) is taken as + [111] and +z 
for the zinc blende and wurzite forms respectively, whereas for the general class of polar crystals, the 
+ z direction is taken as the outward normal from the z-cut face that develops a negative charge on 
compression along z. 

In general, the SHG-coefficients are determined relative to a standard material, such as a-Si0 2 
(quartz), KH 2 P0 4 (KDP) or NH 4 H 2 P0 4 (ADP). In order to convert from relative to absolute values we 
have taken the values of SHG standard coefficients as 

d™* = (5.7 ± 0.7) x KT 13 m/V 

df£P = (4.73 ± 0.3) x 10- 13 m/V (38) 

jQuartz = (3 64 ± Q 4) x l()- 13 m/V. 

In Table 18-2 only single crystal data are included. Other tabulations, which include data on 
powders, have been given by Bechmann and Kurtz. 58 

In Table 18-4 the refractive indices of some of the nonlinear materials are given. For uniaxial 
crystals, n e and n represent the extraordinary and ordinary indices respectively. For biaxial crystals we 
have followed the convention that the principal refractive indices are in the order 

n y >n ft >n aL . (39) 

The single-term dispersion equations given in a table of the refractive indices are valid only for the 
wavelength range of that table. We have followed the IRE Convention 19 in determining the relations 
among the principal axes a, /? and y, the crystallographic axes a, b and c, and the piezoelectric axes X, Y 
and Z. Where dispersion equations for the refractive indices are available, they are included in the 
tables of refractive indices. Since the absolute or relative signs of the second harmonic coefficients 
have been experimentally determined for only a limited number of materials, such signs are listed in a 
separate Table 18-3. 



508 Handbook of Lasers 

TABLE 18-4. REFRACTIVE INDICES 



18.4.1 ALUMINUM PHOSPHATE 

(A1P0 4 ) 
Room Temperature (Ref.12 ) 



18.4.3b AMMONIUM DIHYDROGEN 
PHOSPHATE (ADP) 

Room Temperature {Ref 121) 



Wavelength 






(>tm) 


n„ 


«e 


0.4 


1.5369 


1.5465 


0.5 


1.5287 


1.5385 


0.6 


1.5243 


1.5334 


0.7 


1.5215 


1.5301 


0.8 


1.5192 


1.5281 


1.0 


1.5161 


1.5245 


1.2 


1.5136 


1.5223 


1.4 


1.5112 


1.5198 


1.6 


1.5088 


1.5174 


1.8 


1.5062 


1.5145 


2.0 


1.5034 


1.5116 


2.2 


1.5001 


1.5083 


2.4 


1.4969 


1.5048 


2.6 


1.4928 


1.5006 




18.4.2 




AMMONIUM DJDEUTERIUM PHOSPHATE 




(ADDP) 




Room Temperature {Ref. Ill) 


Wavelength 






{jxm) 


n a 


n e 


0.350 


1.5414 


1.4923 


0.530 


1.5198 


1.4784 


0.690 


1.5142 


1.4737 


1.060 


1.5088 


1.4712 



Wavelength 






(jj,m) 


n 


n e 


0.2138560 


1.62598 


1.56738 


0.2288018 


1.60785 


1.55138 


0.2536519 


1.58688 


1.53289 


0.2967278 


1.56462 


1.51339 


0.3021499 


1.56270 


1.51163 


0.3125663 


1.55917 


1.50853 


0.3131545 


1.55897 


1.50832 


0.3341478 


1.55300 


1.50313 


0.3650146 


1.54615 


1.49720 


0.3654833 


1.54608 


1.49712 


0.3662878 


1.54592 


1.49698 


0.3906410 


1.54174 




0.4046561 


1.53969 


1.49159 


0.4077811 


1.53925 


1.49123 


0.4358350 


1.53578 


1.48831 


0.4916036 




1.48390 


0.5460740 


1.52662 


1.48079 


0.5769590 


1.52478 


1.47939 


0.5790654 


1.52466 


1.47930 


0.6328160 


1.52166 


1.47685 


1.013975 


1.50835 


1.46895 


1.128704 


1.50446 


1.46704 


1.152276 


1.50364 


1.46666 



18.4.3a AMMONIUM DIHYDROGEN 
PHOSPHATE (ADP) 

Room Temperature {Ref. 85) 



Wavelength 
{f*m) 


"0 


«e 


0.3653 
0.4047 
0.4078 
0.4358 
0.4916 

0.5461 
0.5779 
0.6234 
0.6907 


1.5457 
1.5396 
1.5392 
1.5357 
1.5303 

1.5265 
1.5246 
1.5223 
1.5192 


1.4970 
1.4915 
1.4912 
1.4882 
1.4838 

1.4808 
1.4792 
1.4775 
1.4753 



Estimated accuracy = ±0.00003. 

Dispersion Equation : 
n 2 = 2.302484 

+ 1.117089 X 10" 10 v 2 /{l - v 2 /7.605372 X 10 9 ) 
+ 3.751806 X 10 6 /(2.5 X 10 s - v 2 ) 

« e 2 = 2.163077 

+ 9.670312 X 10- "i» 2 /(l - v 2 /7.785289 X 10 9 ) 
+ 1.451540 X 10 6 /(2.5 X 10 5 - v 2 ) 
where v = 1/A in cm" l . 

18.4.4 
AMMONIUM OXALATE MONOHYDRATE 
((NH 4 ) 2 C 2 4 H 2 0) 

Room Temperature {Ref 38) 



Estimated accuracy = ±0.0001. 
The change in index of refraction with temperature 
is given by: 

A« = («o 2 - 3.0297n„+ 2.3004) X (0.713 X 10~ 2 ) 
X (298 - T) 

An e = (n e 2 )(0.675 X 10" 6 ) x (298- T), 
where the temperature T is given in °K. 



Wavelength 








(jj.m) 


"«=z 


"/» = !' 


"v=* 


0.4471 


1.4460 


1.5599 


1.6119 


0.4713 


1.4447 


1.5561 


1.6084 


0.4922 


1.4435 


1.5544 


1.6050 


0.5016 


1.4426 


1.5536 


1.6037 


0.5461 


1.4406 


1.5493 


1.5993 


0.5780 


1.4391 


1.5470 


1.5965 


0.5876 


1.4388 


1.5469 


1.5952 


0.6678 


1.4362 


1.5426 


1.5892 


0.7016 


1.4352 


1.5408 


1.5874 


1.014 


1.4295 


1.5312 


1.5763 


1.129 


1.4276 


1.5284 


1.5728 


1.367 


1.4235 


1.5222 


1.5652 



18 Non-Linear Optical Materials 509 



TABLE 18-4. REFRACTIVE INDICES (Continued) 



18.4.5 BARIUM SODIUM NIOBATE 
(Ba 2 NaNb 5 15 ) 

Room Temperature {Ref 87) 



Wavelength 








(ftm) 


«a=c=Z 


fl0=a=X 


n T =b=r 


0.4579 


2.2931 


2.4266 


2.4284 


0.4765 


2.2799 


2.4076 


2.4094 


0.4880 


2.2727 


2.3974 


2.3991 


0.4965 


2.2678 


2.3903 


2.3920 


0.5017 


2.2649 


2.3862 


2.3879 


0.5145 


2.2583 


2.3767 


2.3786 


0.5321 


2.2502 


2.3655 


2.3672 


0.6328 


2.2177 


2.3205 


2.3222 


1.0642 


2.1700 


2.2567 


2.2580 



Dispersion Equation : 

re. 2 - 1 = 3.6008A 2 /[A 2 - (0.17944) 2 ] 
re, 2 - 1 = 3.9495A 2 /[A 2 - (0.20035) 2 ] 
n 2 - 1 = 3.9495A 2 /[A 2 - (0.20097) 2 ] 



18.4.7 BENZIL KC 6 H 5 ) 2 (CO) 2 ] 

Room Temperature {Ref. 23) 

Wavelength 

(jxm) n n e 



0.4205 
0.4358 
0.4380 
0.4620 
0.4860 

0.5461 
0.5780 
0.5893 
0.6560 



Dispersion Equation: 

n 2 - 1 = 1.08 + 0.535A 2 /[A 2 - (0.24) 2 ] 
+ 0.0l50A 2 /[A 2 -(0.398) 2 ] 

« e 2 - 1 = 1.35+ 0.370A 2 /[A 2 - (0.24) 2 ] 
+ 0.0138A 2 /[A 2 -(0.395) 2 ] 

where A is in /xm. 



1.737 


1.737 


1.716 


1.720 


1.712 


1.718 


1.694 


1.705 


1.682 


1.695 


1.667 


1.684 


1.660 


1.680 


1.658 


1.679 


1.648 


1.672 



18.4.6 BARIUM TITANATE 
(BaTi0 3 ) 

Room Temperature {Ref. 93) 



Wavelength 
(/im) 



n e 



0.4579 


2.5637 


2.4825 


0.4765 


2.5355 


2.4605 


0.4880 


2.5206 


2.4487 


0.5145 


2.4917 


2.4255 


0.5321 


2.4760 


2.4128 


0.6328 


2.4164 


2.3637 


1.0642 


2.3379 


2.2970 


2.1284 


2.2947 


2.2593 



Dispersion Equation : 

«„ 2 - 1 = 4.239A 2 /[A 2 - (0.2229) 2 ] 
n e 2 — 1 = 4.0854A 2 /[A 2 - (0.2087) 2 ] 
where A is in /xm. 



18.4.8 BERYLLIUM OXIDE (BeO) 




22.4°C. {Ref. 79) 




Wavelength 






(/xm) 


n„ 


n e 


0.430 


1.73039 




0.440 


1.72924 


1.74556 


0.450 


1.72820 


1.74447 


0.460 


1.72725 


1.74348 


0.470 


1.72626 


1.74251 


0.480 


1.72542 


1.74162 


0.490 


1.72460 


1.74073 


0.500 


1.72388 


1.74002 


0.510 


1.72308 


1.73918 


0.520 


1.72249 


1.73852 


0.530 


1.72177 


1.73779 


0.540 


1.72121 


1.73703 


0.550 


1.72062 


1.73644 


0.560 


1.72006 


1.73588 


0.570 


1.71950 


1.73530 


0.580 


1.71903 


1.73477 


0.590 


1.71856 


1.73423 


0.600 


1.71795 


1.73381 


0.610 


1.71762 


1.73322 


0.620 


1.71710 


1.73279 


0.630 


1.71668 


1.73233 


0.640 


1.71632 


1.73191 


0.650 


1.71589 


1.73156 


0.660 


1.71554 


1.73113 


0.670 


1.71517 


1.73075 


0.680 


1.71482 


1.73041 


0.690 


1.71450 





Dispersion equation: 

n 2 - 1 = 1.919087A 2 /(A 2 - 0.00727575) 
+ 3.972323A 2 /(A 2 - 199.31087) 

n 2 - 1 = 1.972142A 2 /(A 2 - 0.00748564) 
+ 17.5787A 2 /(A 2 - 779.49122) 

where A is expressed in /*m. 



510 Handbook of Lasers 

TABLE 18-4. REFRACTIVE INDICES (Continued) 



18.4.9 BISMUTH GERMANIUM OXIDE 
(Bi 4 Ge0 12 ) 

Room Temperature (Ref 103) 

Wavelength 

()U.m) n 



0.4765 


2.142 


0.4880 


2.135 7 


0.4965 


2.131s 


0.5017 


2.128s 


0.5145 


2.123 7 


0.5321 


2.115 2 


0.6328 


2.086! 


1.0642 


2.044 3 



Dispersion Equation : 

n 2 - 1 = 3.08959A 2 /(A 2 - 0.01337). 
where A is in ju.m. 

18.4.10 CADMIUM MERCURY THIOCYANATE 

27° C (Ref. 109) 



Wavelength 
(/urn) 



«o 



n e 



0.530 
0.633 
1.06 



2.003 s 

1.970 

1.924 5 



1.792 
1.753 
1.728 



18.4.11 CADMIUM SELENIDE (CdSe) 

Room Temperature (Ref. 12) 



Wavelength 






(/xm) 


n 


n e 


0.8 


2.6448 


2.6607 


0.9 


2.5826 


2.6027 


1.0 


2.5502 


2.5696 


1.2 


2.5132 


2.5331 


1.4 


2.4929 


2.5133 


1.6 


2.4818 


2.5008 


1.8 


2.4732 


2.4930 


2.0 


2.4682 


2.4873 


2.2 


2.4642 


2.4840 


2.4 


2.4612 


2.4798 


2.6 


2.4590 


2.4784 


2.8 


2.4562 


2.4757 


3.0 


2.4542 


2.4741 


3.2 


2.4532 


2.4726 


3.4 


2.4518 


2.4714 


3.6 


2.4509 


2.4702 


3.8 


2.4498 


2.4694 


4.0 


2.4491 


2.4685 



18.4.12 CADMIUM SULFIDE 

(CdS) 

Room Temperature (Ref. 5) 



Wavelength 
(/Am) 



n„ 



0.5120 




2.751 


0.5130 




2.743 


0.5140 




2.737 


0.5150 


2.743 


2.726 


0.5160 


2.735 


2.720 


0.5170 


2.727 


2.714 


0.5180 


2.718 


2.706 


0.5190 


2.709 


2.702 


0.5200 


2.702 


2.698 


0.5210 


2.700 


2.694 


0.5220 


2.694 


2.689 


0.5230 


2.687 


2.685 


0.5240 


2.681 


2.680 


0.5250 


2.674 


2.675 


0.5275 


2.661 


2.665 


0.5300 


2.649 


2.654 


0.5325 


2.638 


2.644 


0.5350 


2.628 


2.637 


0.5375 


2.617 


2.628 


0.5400 


2.609 


2.622 


0.5425 


2.602 


2.612 


0.5450 


2.594 


2.606 


0.5475 


2.587 


2.600 


0.5500 


2.580 


2.593 


0.5750 


2.528 


2.545 


0.6000 


2.493 


2.511 


0.6250 


2.467 


2.484 


0.6500 


2.446 


2.463 


0.6750 


2.427 


2.446 


0.7000 


2.414 


2.432 


0.7500 


2.390 


2.409 


0.8000 


2.374 


2.392 


0.8500 


2.364 


2.378 


0.9000 


2.359 


2.368 


0.9500 


2.341 


2.359 


1.0000 


2.334 


2.352 


1.0500 


2.328 


2.346 


1.1000 


2.324 


2.340 


1.1500 


2.320 


2.336 


1.2000 


2.316 


2.332 


1.2500 


2.312 


2.329 


1.3000 


2.309 


2.326 


1.3500 


2.306 


2.323 


1.4000 


2.304 


2.321 



18 Non-Linear Optical Materials 
TABLE 18-4. REFRACTIVE INDICES (Continued) 



511 



18.4.13 CADMIUM TELLURIDE 
(CdTe) 

Room Temperature (Ref. 60) 



Wavelength 




(H 


n 


0.903 


2.91 


1.0 


2.84 


1.1 


2.81 


1.0-1.3 


2.82 


7.0-10.0 


2.69 


10.0 


2.69 


14.0 


2.69 



Dispersion equation: 

„2 _ 1 = 4.68 + 1.53A 2 /(A 2 - 0.366), 
where A is in /urn. 



18.4.16 CUPROUS IODIDE 
(Cul) 

Room Temperature (Ref. 25) 



Wavelength 
(jLtm) 



0.4358 


2.562 x ± 0.002 


0.4678 


2.461 7 ± 0.002 


0.4800 


2.448 5 ± 0.002 


0.5086 


2.41 1 ± 0.002 


0.5461 


2.372 6 ± 0.002 


0.5791 


2.347s ± 0.002 


0.5896 


2.342 8 ± 0.002 


0.6438 


2.31 5 6 ± 0.002 


0.7699 


2.280 2 ± 0.004 



18.4.14 CUPROUS BROMIDE 
(CuBr) 

Room Temperature (Ref. 25) 



Wavelength 



0.4358 


2.336s ± 0.002 


0.4678 


2.229 ± 0.002 


0.4800 


2.207 2 ± 0.002 


0.5086 


2.171 5 ± 0.002 


0.5461 


2.141^0.002 


0.5791 


2.122i ± 0.002 


0.5896 


2.117 4 ± 0.002 


0.6438 


2.096 9 ± 0.002 


0.7699 


2.069s ± 0.004 



18.4.15 CUPROUS CHLORIDE 

(CuCl) 

Room Temperature (Ref. 25) 



18.4.17 GADOLINIUM MOLYBDATE 




(Gd 2 (Mo0 4 ) 3 ) 




Room Temperature 


(Ref. 97) 




Wavelength 








(/tin) 


n a =b=Y 


Hp=a=X 


n y=c =z 


0.4579 


1.8758 


1.8762 


1.9342 


0.4765 


1.8694 


1.8699 


1.9270 


0.4880 


1.8659 


1.8663 


1.9229 


0.4965 


1.8634 


1.8639 


1.9201 


0.5017 


1.8621 


1.8625 


1.9185 


0.5145 


1.8588 


1.8593 


1.9148 


0.5321 


1.8545 


1.8549 


1.9102 


0.6328 


1.8385 


1.8390 


1.8915 


1.064 


1.8142 


1.8146 


1.8637 



Dispersion equation: 

n 2 - 1 = 2.2450A 2 /(A 2 - 0.022693) 
n p 2 - 1 = 2.24654A 2 /(A 2 - 0.0226803) 
n 2 - 1 = 2.41957A 2 /(A 2 - 0.0245458) 
where A is in fim. 



Wavelength 
(ftm) 



0.4047 


2.153s ±0.001 


0.4078 


2.141 ± 0.001 


0.4358 


2.072 ± 0.001 


0.4678 


2.033 6 ± 0.001 


0.4800 


2.023 4 ± 0.001 


0.5086 


2.004 2 ± 0.001 


0.5461 


1.987 ± 0.001 


0.5791 


1.976 ± 0.001 


0.5896 


1.972 6 ± 0.001 


0.6438 


1.958 4 ± 0.001 



18.4.18 GALLIUM ARSENIDE 

(GaAs) 
Room Temperature {Ref. 61) 



0.7699 



1.941 ±0.002 



Wavelength 




(Aim) 


n 


1.127 


3.455 


1.239 


3.425 


1.377 


3.400 


1.550 


3.375 


1.652 


3.366 



512 Handbook of Lasers 

TABLE 18-4. REFRACTIVE INDICES (Continued) 



18.4.19a GALLIUM PHOSPHIDE (GaP) 
Room Temperature (Ref. 12) 



18.4.20 HEXAMETHYLENETETRAMINE 

Room Temperature {Ref. 57) 



Wavelength 






v>m) 


n 




0.5 


3.4595 




0.6 


3.3495 




0.7 


3.2442 




0.8 


3.1830 




0.9 


3.1430 




1.0 


3.1192 




1.1 


3.0981 




1.2 


3.0844 




1.4 


3.0646 




1.6 


3.0509 




1.8 


3.0439 




2.0 


3.0379 




2.2 


3.0331 




2.4 


3.0296 




2.6 


3.0271 




2.8 


3.0236 




3.0 


3.0215 




3.2 


3.0197 




3.4 


3.0181 




3.6 


3.0166 




3.8 


3.0159 




4.0 


3.0137 





Wavelength 
(/urn) 


n 


0.4861 
0.5016 
0.5461 
0.5780 
0.5876 

0.6676 


1.5984 
1.5953 
1.5917 
1.5899 
1.5893 

1.5856 



18.4.21 HIPPURIC ACID 

Room Temperature {Ref. 117) 



Wavelength 



«a 



n p 



« v 



0.350 
0.589 
0.700 



1.55 

1.5348 

1.534 



1.61 

1.5921 

1.589 



1.78 

1.7598 

1.755 



18.4.19b GALLIUM PHOSPHIDE (GaP) 

24.5° C {Ref. 78) 



Wavelength 



18.4.22 INDIUM ANTIMONIDE 

(InSb) 
Room Temperature {Ref. 2) 

Wavelength 
(yum) 



0.545 


3.4522 






0.550 


3.4411 


7.87 


4.0 


0.560 


3.4203 


8.00 


3.99 


0.570 


3.4012 


9.01 


3.96 


0.580 


3.3837 


10.06 


3.95 


0.590 


3.3675 


11.01 


3.93 


0.600 


3.3524 


12.06 


3.92 


0.610 


3.3384 


12.98 


3.91 


0.620 


3.3254 


13.90 


3.90 


0.630 


3.3132 


15.13 


3.88 


0.640 


3.3018 


15.79 


3.87 


0.650 


3.2912 


16.96 


3.86 


0.660 


3.2811 


17.85 


3.85 


0.670 


3.2716 


18.85 


3.84 


0.680 


3.2626 


19.98 


3.82 


0.690 


3.2541 


21.15 


3.81 


0.700 


3.2462 


22.20 


3.80 



Estimated accuracy = ±0.0012. 



18 Non-Linear Optical Materials 513 



TABLE 18-4. REFRACTIVE INDICES (Continued) 



18.4.23 IODIC ACID (a-HI0 3 ) 

Room Temperature (Ref 56) 



Wavelength 








(H 


n<t= a =x 


flp = c = Z 


n y -i,=r 


0.450 


1.8798 


2.0184 


2.0560 


0.500 


1.8621 


1.9930 


2.0192 


0.5325 


1.8547 


1.9829 


2.0103 


0.550 


1.8497 


1.9787 


2.0049 


0.600 


1.8409 


1.9665 


1.9922 


0.650 


1.8352 


1.9571 


1.9812 


0.700 


1.8308 


1.9505 


1.9765 


0.800 


1.8250 


1.9407 


1.9672 


0.850 


1.8223 


1.9378 


1.9639 


0.900 


1.8206 


1.9347 


1.9595 


0.950 


1.8180 


1.9318 


1.9564 


1.000 


1.8147 


1.9292 


1.9537 


1.065 


1.8123 


1.9275 


1.9508 


1.100 


1.8116 


1.9260 


1.9484 


1.200 


1.8086 


1.9230 


1.9436 



18.4.24 LEAD NIOBATE (PbNb^On) 

Room Temperature {Ref. 98) 



Wavelength 








(/Am) 


fl a = a = X 


«/j = b = y 


n y=c =z 


0.4579 


2.4754 


2.4766 


2.5047 


0.4765 


2.4554 


2.4571 


2.4845 


0.4880 


2.4445 


2.4465 


2.4735 


0.4965 


2.4371 


2.4392 


2.466 


0.5017 


2.4329 


2.435 


2.4618 


0.5145 


2.4231 


2.4254 


2.4518 


0.5321 


2.4113 


2.4137 


2.4396 


0.6328 


2.3644 


2.3667 


2.3922 


1.0642 


2.2979 


2.301 


2.3254 



Dispersion equation : 

n 2 - 1 = 4.124A 2 /[A 2 - (0.202) 2 ] 
n p 2 - 1 = 4.139A 2 /[A 2 - (0.201 1) 2 ] 
„ y 2 _ i = 4.246A 2 /[A 2 - (0.2014) 2 ] 
where A is in /xm. 

18.4.25 LEAD TITANATE (PbTi0 3 ) 

Room Temperature {Ref. 94) 



Wavelength 
(>m) 


"o 


n e 


0.4880 
0.5017 
0.5145 
0.5321 
0.6328 

1.0642 
1.152 


2.793 

2.7742 

2.7586 

2.7398 

2.6676 

2.5712 
2.5637 


2.7744 
2.7574 
2.7431 
2.7260 
2.6594 

2.5692 
2.5623 



Dispersion equation : 

n 2 - 1 = 5.359A 2 /[A 2 - (0.224) 2 ] 
n e 2 - 1 = 5.365A 2 /[A 2 - (0.2170) 2 ], 
where A is in /xm. 



18.4.26 LITHIUM FORMATE MONOHYDRATE 
(LiCH0 2 H 2 0) 

Room Temperature (Ref. 88) 



Wavelength 








(jjm) 


n t=x =a 


np = y=b 


Wy=Z=C 


0.4579 


1.3708 


1.4901 


1.5308 


0.4765 


1.3698 


1.4883 


1.5286 


0.4880 


1.3692 


1.4873 


1.5272 


0.4965 


1.3688 


1.4866 


1.5264 


0.5017 


1.3686 


1.4862 


1.5258 


0.5145 


1.3680 


1.4851 


1.5245 


0.5321 


1.3675 


1.4838 


1.5229 


0.6328 


1.3645 


1.4784 


1.5163 


1.0642 


1.3593 


1.4673 


1.5035 



Dispersion equation : 

„S - l = 0.841 5A 2 /[A 2 - (0.0953) 2 ] 
n & 2 - 1 = 1.14106A 2 /[A 2 - (0.1 183) 2 ] 
« v 2 - 1 = 1.2454A 2 /[A 2 - (0.12496) 2 ], 
where A is in fim. 

18.4.27a LITHIUM GALLIUM OXIDE (LiGa0 2 ) 

Room Temperature {Ref 58) 



Wavelength 
(fim) 


n«=r 


np= z 


n y =x 


0.4700 
0.5000 
0.5400 
0.5800 
0.6200 

0.6600 


1.7534 
1.7477 
1.7407 
1.7351 
1.7311 

1.7289 


1.7835 
1.7768 
1.7683 
1.7626 
1.7589 

1.7578 


1.7852 
1.7791 
1.7708 
1.7653 
1.7617 

1.7604 



18.4.27b LITHIUM GALLIUM OXIDE (LiGa0 2 ) 

Room Temperature (Ref 71) 



Wavelength 






(>m) 


n„,p=Y, z 


n y = x 


0.4100 


1.7702 


1.804 


0.4500 


1.757 


1.7895 


0.5000 


1.7466 


1.7785 


0.5500 


1.7395 


1.7702 


0.6000 


1.7343 


1.7615 


0.7000 


1.7268 


1.7565 


0.8000 


1.7218 


1.7507 


0.9000 


1.7185 


1.7475 


1.0000 


1.716 


1.7445 


1.2000 


1.7122 


1.7405 


1.4000 


1.7095 


1.7372 


1.6000 


1.707 


1.735 


1.8000 


1.7045 


1.7325 


2.0000 


1.7025 


1.7303 


2.2000 


1.7005 


1.7268 


2.4000 


1.6978 


1.7242 


2.6000 


1.6955 


1.7225 


2.8000 


1.6925 


1.720 



514 Handbook of Lasers 



TABLE 18-4. REFRACTIVE INDICES (Continued) 



18.4.28a LITHIUM IODATE 
(LiI0 3 ) 

Room Temperature (Ref. 91) 



Wavelength 






ipm) 


"o 


n e 


0.4579 


1.9186 


1.7633 


0.4765 


1.9124 


1.7586 


0.4880 


1.9089 


1.7560 


0.4965 


1.9065 


1.7541 


0.5017 


1.9051 


1.7531 


0.5145 


1.9018 


1.7506 


0.5321 


1.8978 


1.7475 


0.6328 


1.8815 


1.7351 


1.0642 


1.8517 


1.7168 



Dispersion equation : 

n 2 - 1 = 2.40109A 2 /(A 2 - 0.021865) 
ne 2 - 1 = 1.91359A 2 /(A 2 - 0.01940), 
where A is in pm. 



18.4.28b LITHIUM IODATE 
(LiI0 3 ) 

Room Temperature {Ref. 77) 



Wavelength 
(jxm) 


n» 


n e 


0.4000 
0.4360 
0.5000 
0.5300 
0.5780 

0.6900 
0.8000 
1.060 


1.948 
1.931 
1.908 
1.901 
1.888 

1.875 
1.868 
1.860 


1.780 
1.766 
1.754 
1.750 
1.742 

1.731 
1.724 
1.719 



18.4.29 LITHIUM NIOBATE 
(LiNb0 3 ) 

Room Temperature {Ref. 14a) 



Wavelength 






(fim) 


n 


n e 


0.42 


2.4144 


2.3638 


0.45 


2.3814 


2.2765 


0.50 


2.3444 


2.2446 


0.55 


2.3188 


2.2241 


0.60 


2.3002 


2.2083 


0.70 


2.2862 


2.1964 


0.80 


2.2756 


2.1874 


0.90 


2.2598 


2.1741 


1.00 


2.2487 


2.1647 


1.20 


2.2407 


2.1580 


1.40 


2.2291 


2.1481 


1.60 


2.2208 


2.1410 


1.80 


2.2139 


2.1351 


2.00 


2.2074 


2.1297 


2.20 


2.2015 


2.1244 


2.40 


2.1948 


2.1187 


2.60 


2.1882 


2.1138 


2.80 


2.1814 


2.1080 


3.00 


2.1741 


2.1020 


3.20 


2.1663 


2.0955 


3.40 


2.1580 


2.0886 


3.60 


2.1493 


2.0814 


3.80 


2.1398 


2.0735 


4.00 


2.1299 


2.0652 


4.20 


2.1193 


2.0564 



Temperature-dependent dispersion equation 
(Ref. 41): 



Wo 2 - 1 = 3.9130 + 



1.173 X 10 5 + 1.65 X 10- 2 T' 



A 2 - (2.12 X 10 2 + 2.7X 10- 5 r 2 ) 2 
-2.78X 10- 8 x A 2 
rte 2 - 1 = 3.5567 + 2.605 X 10" 7 J 2 
0.970 X 10 5 + 2.70 x 10- 2 r 2 



A 2 - (2.01 x 10 2 + 5.4 x 10" 5 r 2 ) 2 
where A is in /xm. 



2.24 X 10- 8 A 2 . 



18 Non-Linear Optical Materials 
TABLE 18-4. REFRACTIVE INDICES (Continued) 



515 



18.4.30. LITHIUM SULFATE MONOHYDRATE 
(LiS0 4 H 2 0) 

Room Temperature (Ref. 38) 



18.4.32 MERCURY SULFIDE 

(a-HgS) 

Room Temperature (Ref. 13) 



Wavelength 








(jum) 


«a 


n„ 


n y 


0.3650 


1.4771 


1.4926 


1.5029 


0.4047 


1.4722 


1.4876 


1.4980 


0.4358 


1.4693 


1.4849 


1.4951 


0.4471 


1.4686 


1.4834 


1.4941 


0.4713 


1.4670 




1.4926 


0.5016 


1.4652 


1.4802 


1.4905 


0.5461 


1.4631 


1.4782 


1.4882 


0.5780 


1.4619 


1.4772 


1.4867 


0.5876 


1.4616 


1.4766 


1.4866 


0.6678 


1.4593 


1.4743 


1.4838 


0.7016 


1.4585 




1.4831 


1.014 


1.4538 


1.4678 


1.4777 


1.129 


1.4525 


1.4666 


1.4761 


1.367 


1.4502 


1.4636 


1.4732 


1.530 


1.4485 




1.4708 


1.709 


1.4466 


1.4588 


1.4676 



18.4.31 LITHIUM TANTALATE 

(LiTa0 3 ) 

Room Temperature (Ref. 12) 



Wavelength 






(ixm) 


n 


n e 


0.45 


2.2420 


2.2468 


0.50 


2.2160 


2.2205 


0.60 


2.1834 


2.1878 


0.70 


2.1652 


2.1696 


0.80 


2.1538 


2.1578 


0.90 


2.1454 


2.1493 


1.00 


2.1391 


2.1432 


1.20 


2.1305 


2.1341 


1.40 


2.1236 


2.1273 


1.60 


2.1174 


2.1213 


1.80 


2.1120 


2.1170 


2.00 


2.1066 


2.1115 


2.20 


2.1009 


2.1053 


2.40 


2.0951 


2.0993 


2.60 


2.0891 


2.0936 


2.80 


2.0825 


2.0871 


3.00 


2.0755 


2.0799 


3.20 


2.0680 


2.0727 


3.40 


2.0601 


2.0649 


3.60 


2.0513 


2.0561 


3.80 


2.0424 


2.0473 


4.00 


2.0335 


2.0377 



Wavelength 






(/xm) 


n 


"e 


0.62 


2.9028 


3.2560 


0.65 


2.8655 


3.2064 


0.68 


2.8384 


3.1703 


0.70 


2.8224 


3.1489 


0.80 


2.7704 


3.0743 


0.90 


2.7383 


3.0340 


1.00 


2.7120 


3.0050 


1.20 


2.6884 


2.9680 


1.40 


2.6730 


2.9475 


1.60 


2.6633 


2.9344 


1.80 


2.6567 


2.9258 


2.00 


2.6518 


2.9194 


2.20 


2.6483 


2.9146 


2.40 


2.6455 


2.9108 


2.60 


2.6433 


2.9079 


2.80 


2.6414 


2.9052 


3.00 


2.6401 


2.9036 


3.20 


2.6387 


2.9017 


3.40 


2.6375 


2.9001 


3.60 


2.6358 


2.8987 


3.80 


2.6353 


2.8971 


4.00 


2.6348 


2.8963 


5.00 


2.6267 


2.8863 


6.00 


2.6233 


2.8799 


7.00 


2.6156 


2.8741 


8.00 


2.6112 


2.8674 


9.00 


2.6066 


2.8608 


10.00 


2.6018 


2.8522 


11.00 


2.5914 


2.8434 




18.4.33 




POTASSIUM DIDEUTERIUM PHOSPHATE 




(KDDP) 




Room Temperature (Ref. 85) 


Wavelength 






(fim) 


"o 


n e 


0.4047 


1.5189 


1.4776 


0.4078 


1.5185 


1.4772 


0.4358 


1.5155 


1.4747 


0.4916 


1.5111 


1.4710 


0.5461 


1.5079 


1.4683 


0.5779 


1.5063 


1.4670 


0.6234 


1.5044 


1.4656 


0.6907 


1.5022 


1.4639 


1.0000 


1.4700 


1.4400 



Estimated accuracy = ±0.0001 

The change in index of refraction with temperature 
is given by: 

An„= (n 2 - 1.047) X (0.228 X 10" 4 )(298 - T) 

A« e = (n e 2 ) X (0.955 X 10" 5 )(298 - T), 
where T is in °K. 



516 



Handbook of Lasers 



TABLE 18-4. REFRACTIVE INDICES (Continued) 



18.4.34 POTASSIUM DIHYDROGEN 
ARSENATE (KDA) 

Room Temperature (Ref 118) 



Wavelength 






0*m) 


n„ 


M e 


0.4861 


1.5762 


1.5252 


0.5460 


1.5707 


1.5206 


0.5893 


1.5674 


1.5179 


0.6563 


1.5632 


1.5146 




18.4.35a 




POTASSIUM DIHYDROGEN PHOSPHATE 




(KDP) 




Room Temperature {Ref. 121) 


Wavelength 






(/xm) 


"o 


n e 


0.2138560 


1.60177 


1.54615 


0.2288018 


1.58546 




0.2446950 


1.57228 




0.2464068 


1.57105 




0,2536519 


1.56631 


1.51586 


0.2800869 


1.55263 


1.50416 


0.2980628 


1.54618 


1.49824 


0.3021499 


1.54433 


1.49708 


0.3035781 




1.49667 


0.3125663 


1.54117 


1.49434 


0.3131545 


1.54098 


1.49419 


0.3341478 




1.48954 


0.3650146 


1.52932 


1.48432 


0.3654833 


1.52923 


1.48423 


0.3662878 


1.52909 


1.48409 


0.3906410 




1.48089 


0.4046561 


1.52341 


1.47927 


0.4077811 


1.52301 


1.47898 


0.4358350 


1.51900 


1.47640 


0.4916036 




1.47254 


0.5460740 


1.51152 


1.46982 


0.5769580 


1.50987 




0.5790654 


1.50977 


1.46856 


0.6328160 


1.50737 


1.46685 


1.013975 


1.49535 


1.46041 


1.128704 


1.49205 


1.45917 


1.152276 


1.49135 


1.45893 


1.357070 


1.48455 




1.523100 




1.45521 


1.529525 




1.45512 



18.4.35b 

POTASSIUM DIHYDROGEN PHOSPHATE 

(KDP) 

Room Temperature (Ref. 85) 



Wavelength 






(jj.m) 


n a 


n e 


0.3653 


1.5292 


1.4843 


0.4047 


1.5235 


1.4795 


0.4078 


1.5232 


1.4792 


0.4358 


1.5200 


1.4766 


0.4916 


1.5152 


1.4727 


0.5461 


1.5117 


1.4700 


0.5791 


1.5099 


1.4686 


0.6234 


1.5079 


1.4672 


0.6907 


1.5052 


1.4655 



Estimated accuracy = ±0.0001 
The change in index of refraction with temperature 
is given by: 

An„ = (n 2 - 1.432) X (0.402 X 10" 4 ) X (298 - T) 
An e =(n e 2 - 1.105) X (0.221 X 10- 4 ) X (298- T) 
where the temperature Tis in °K. 



18.4.36 POTASSIUM DITHIONATE 

(K 2 S 2 6 ) 
Room Temperature (Ref. 40) 



Wavelength 






(jxm) 


n„ 


n e 


0.313 


1.480 


1.568 


0.334 


1.475 


1.557 


0.365 


1.470 


1.546 


0.405 


1.465 


1.537 


0.436 


1.463 


1.530 


0.546 


1.456 


1.518 


0.578 


1.455 


1.516 


1.014 


1.448 


1.503 


1.367 


1.446 


1.500 


1.709 


1.444 


1.498 


2.930 


1.436 


1.489 


3.39 


1.430 


1.485 



Dispersion equation: 
2 = 2.259276 + 1.008956 

X 10- 10 v 2 /(l - v 2 /7.726408 x 10 9 ) 
3.251305 X 10 6 



+ 



(2.5 X 10 5 - v 2 ) 

n 2 = 2.132668 + 8.637494 X 10~ l ^/(l - v 2 /.142631 
X 10 9 )+ 8.069981 X 10 5 /(2.5 X 10 s - v 2 ) 
where v = 1/A in cm - *. 



18 Non-Linear Optical Materials 
TABLE 18-4. REFRACTIVE INDICES (Continued) 



517 



18.4.37 POTASSIUM LITHIUM NIOBATE 
(K 3 Li 2 Nb 5 15 ) 

Room Temperature {Ref. 114) 



Wavelength 






(f«n) 


n„ 


n e 


0.4500 


2.4049 


2.2512 


0.4750 


2.3751 


2.2315 


0.5000 


2.3546 


2.2144 


0.5250 


2.3349 


2.2010 


0.5324 


2.3260 


2.1975 


0.5500 


2.3156 


2.1900 


0.5750 


2.3016 


2.1801 


0.6000 


2.2899 


2.1720 


0.6250 


2.2799 


2.1645 


0.6500 


2.2711 


2.1586 


0.6750 


2.2631 


2.1529 



18.4.41 PROUSTITE 






(Ag 3 AsS 3 ) 






20° C {Ref. 42) 




Wavelength 






(/um) 


n„ 


n e 


0.5876 




2.7896 


0.6328 


3.0190 


2.7391 


0.6678 


2.9804 


2.7094 


1.0140 


2.8264 


2.5901 


1.1290 


2.8067 


2.5756 


1.3670 


2.7833 


2.5570 


1.530 


2.7728 


2.5485 


1.709 


2.7654 


2.5423 


2.50 


2.7478 


2.5282 


3.56 


2.7379 


2.5213 


4.62 


2.7318 


2.5178 



Dispersion equation: 

« 2 - 1 = 3.708A 2 /(A 2 - 0.04601) 

n e 2 - 1 = 3.349A 2 /(A 2 - 0.03564) 

18.4.38 

POTASSIUM SODIUM BARIUM NIOBATE 

(K»N ai -»Ba 2 Nb50 15 ) 

Dispersion equations at 22° C {Ref. 105): 

nl = 3.6680 + 24.681/ [(4.3004) 2 - (1.2394/A) 2 ] 
n\ = 2.9198 + 46.737/[(5.1605) 2 - (1.2394/A) 2 ], 
where A is in /xm. 



Dispersion equation : 
„ o 2 = 7.483 + 0.474/(A 2 - 0.09) - 0.0019A 2 
n 2 = 6.346 + 0.342/(A 2 - 0.09) - 0.0011 A 2 





18.4.39 






POTASSIUM TARTRATE HEMIHYDRATE 




(K 2 C4H40 6 1/2H 2 0) 




Room Temperature 


• {Ref. 38) 




Wavelength 








(fim) 


"« 


n„ 


"v 


0.3650 


1.5156 


1.5487 


1.5630 


0.4047 


1.5090 


1.5409 


1.5541 


0.4358 


1.5049 


1.5368 


1.5494 


0.5461 


1.4961 


1.5271 


1.5384 


0.5780 


1.4945 


1.5253 


1.5363 


1.014 


1.4846 


1.5142 


1.5238 


1.129 


1.4832 


1.5127 


1.5218 


1.367 


1.4809 


1.5102 


1.5183 



18.4.40 PYRARGYRTTE (Ag 3 SbS 3 ) 
Dispersion equations at room temperature {Ref. 28): 

n? - 1 = 6.585A 2 /[A 2 - (0.4) 2 ] 

+ 0.1133A 2 /[A 2 -(15) 2 ] 

« 2 -l = 5.845A 2 /[A 2 -(0.4) 2 ] 

+ 0.0202A 2 /[A 2 -(15) 2 ]. 

where A is in fim. 



18.4.42 QUARTZ 






(a-Si0 2 ) 




Room Temperature {Ref. 2) 


Wavelength 






(/im) 


n„ 


n e 


0.185 


1.65751 


1.68988 


0.198 


1.65087 


1.66394 


0.231 


1.61395 


1.62555 


0.340 


1.56747 


1.57737 


0.394 


1.55846 


1.56805 


0.434 


1.55396 


1.56339 


0.508 


1.54822 


1.55746 


0.5893 


1.54424 


1.55335 


0.7680 


1.53903 


1.54794 


0.8325 


1.53773 


1.54661 


0.9914 


1.53514 


1.54392 


1.1592 


1.53283 


1.54152 


1.3070 


1.53090 


1.53951 


1.3958 


1.52977 


1.53832 


1.4792 


1.52865 


1.53716 


1.5414 


1.52781 


1.53630 


1.6815 


1.52583 


1.53422 


1.7614 


1.52468 


1.53301 


1.9457 


1.52184 


1.53004 


2.0531 


1.52005 


1.52823 


2.3000 


1.51561 




2.6000 


1.50986 




3.0000 


1.49953 




3.5000 


1.48451 




4.0000 


1.46671 




4.2000 


1.4569 




5.000 


1.417 




6.4500 


1.274 




7.000 


1.167 





518 



Handbook of Lasers 



TABLE 18-4. REFRACTIVE INDICES (Continued) 



18.4.43a 
RUBIDIUM DIHYDROGEN PHOSPHATE (RDP) 

Room Temperature (Ref. 96) 



Wavelength 






(/xm) 


«o 


n e 


0.4765 


1.514 


1.4861 


0.4880 


1.5132 


1.4832 


0.4965 


1.5126 


1.4827 


0.5017 


1.5121 


1.4825 


0.5145 


1.5116 


1.4820 


0.5321 


1.5106 


1.4811 


0.6328 


1.4976 


1.4775 


1.0642 


1.4926 


1.4700 



Dispersion equation: 

n 2 - 1 = 1.2068A 2 /(A 2 - 0.01539) 
« e 2 - 1 = 1.15123A 2 /(A 2 — 0.010048) 
where A is in /xm. 



18.4.46 SILVER THIOGALLATE 

(AgGaS 2 ) 
20° C (Ref. 39) 



Wavelength 
v>m) 


"o 


n e 


0.4916 
0.5016 
0.5461 
0.5780 
0.5876 

0.6678 


2.700 
2.683 
2.619 

2.587 
2.579 

2.529 


2.710 
2.676 
2.585 
2.546 
2.537 

2.481 



Dispersion equation : 
n 2 = 5.728 + 0.2410/(A 2 - 0.0870) ■ 
n 2 = 5.497 + 0.2026/(A 2 - 0.1307) • 
where A is in /xm. 



0.00210A 2 
0.00233A 2 : 



18.4.43b 
RUBIDIUM DIHYDROGEN PHOSPHATE (RDP) 

Room Temperature (Ref. 116) 



Wavelength 






(/xm) 


n 


n e 


0.3472 


1.5284 


1.4969 


0.4358 


1.5165 


1.4857 


0.5468 


1.5082 


1.4790 


0.5893 


1.5053 


1.4765 


0.6943 


1.5020 


1.4735 



18.4.47 SODIUM BROMATE 
(NaBr0 3 ) 

Dispersion equation at room temperature (Ref. 22): 

n 2 - 1 = 1.3194A 2 /[A 2 - (0.09) 2 ] 

+ 0.2357A 2 /[A 2 - (0.2) 2 ] - 0.01 74A 2 , 

where A is in /xm. 



18.4.44 SELENIUM (Se) 
Room Temperature (Ref. 30) 



Wavelength 
(/xm) 



1.06 2.790 ± 0.008 3.608 ± 0.008 

1.15 2.737 ± 0.008 3 .573 ± 0.008 

3.39 2.650 ± 0.01 3.460 ± 0.01 

10.60 2.64 ±0.01 3.41 ±0.01 



18.4.45 SILICON CARBIDE (SiC) 
Room Temperature (Ref. 89) 



Wavelength 
(tun) 


n 


Me 


0.4880 
0.5017 
0.5145 
0.5321 
0.6328 

1.0642 


2.6916 
2.6837 
2.6771 
2.6689 
2.6351 

2.5830 


2.7423 
2.7337 
2.7261 
2.7167 
2.6794 

2.6225 



Dispersion equation: 

«„ 2 - 1 = 5.5515A 2 /[A 2 - (0.1625) 2 ] 
n 2 - 1 = 5.7382A a /[A 2 - (0.16897) 2 ], 
where A is in /*m. 



18.4.48 SODIUM CHLORATE 
(NaC10 3 ) 

Room Temperature (Ref. 23) 



Wavelength 




(/xm) 


n 


0.2310 


1.616 


0.2573 


1.585 


0.2748 


1.572 


0.3256 


1.549 


0.3404 


1.544 


0.3467 


1.542 


0.3611 


1.539 


0.4862 


1.522 


0.5173 


1.519 


0.5892 


1.515 


0.6563 


1.513 


0.6867 


1.512 


0.7188 


1.511 



Dispersion equation : 

n 2 - 1 = 1.1825A 2 /[A 2 - (0.09) 2 ] 

+ 0.07992A 2 /[A 2 - (0.185) 2 ] - 0.00864A 2 ; 

where A is in fim. 



18 Non-Linear Optical Materials 
TABLE 18-4. REFRACTIVE INDICES (Continued) 



519 



18.4.49 SODIUM NITRITE (NaN0 2 ) 

Room Temperature (Ref. 37) 



18.4.50 TELLURIUM (Te) 

Room Temperature {Ref. 20) 



18.4.52 </-THREONINE 

Room Temperature (Ref. 100) 



Wavelength 
(/urn) 


n a = a =x 


n e=b=Y 


fly = C = Z 


Wavelength 
(fj,m) 


n a =x 


«/j = r 


«v=z 


0.4358 
0.4800 
0.5086 
0.5461 
0.5791 

0.5889 
0.6438 


1.3531 

1.350 

1.3484 

1.3470 

1.3458 

1.3455 
1.3442 


1.4212 
1.4166 
1.4158 
1.4137 
1.4122 

1.4120 
1.4105 


1.690 

1.675 

1.6685 

1.6620 

1.6567 

1.6555 
1.6510 


0.4579 
0.4765 
0.4880 
0.4965 
0.5017 

0.5145 
0.5321 
0.6328 
1.0642 


1.5299 
1.5282 
1.5272 
1.5266 
1.5263 

1.5254 
1.5243 
1.5196 
1.5114 


1.6039 
1.6017 
1.6004 
1.5996 
1.5991 

1.5979 
1.5965 
1.5898 
1.5788 


1.6125 
1.6100 
1.6087 
1.6077 
1.6072 

1.6059 
1.6043 
1.5974 










1.5855 



Wavelength 






(/mi) 


n 


n e 


4.0 


6.372 


4.929 


5.0 


6.316 


4.864 


6.0 


6.286 


4.838 


7.0 


6.270 


4.821 


8.0 


6.257 


4.809 


9.0 


6.253 


4.802 


10.0 


6.246 


4.796 


12.0 


6.237 


4.789 


14.0 


6.230 


4.785 



Dispersion equation : 

n 2 - 1 = 1.273A 2 /[A 2 - (0.1032) 2 ] 
n„ 2 -l= 1.477A 2 /[A 2 - (0.1 137) 2 ] 
n 2 - 1 = 1.497A 2 /[A 2 - (0.1169) 2 ] 
where A is in /xm. 



18.4.51 TERBIUM MOLYBDATE 

(Tb 2 (Mo0 4 ) 3 ) 

Room Temperature (Ref. 99) 



18.4.53 TOURMALINE 

Room Temperature (Ref. 102) 

















Wavelength 








Qjum) 


««=b=y 


n 0=a=X 


Wy=C=Z 


Wavelength 
(fjum) 


«0 


n e 


0.4579 


1.8864 


1.8867 


1.9433 








0.4765 


1.8797 


1.8800 


1.9358 


0.4765 


1.6474 


1.6273 


0.4880 


1.8760 


1.8764 


1.9316 


0.4880 


1.6465 


1.6263 


0.4965 


1.8734 


1.8739 


1.9288 


0.4965 


1.6457 


1.6255 


0.5017 


1.8720 


1.8724 


1.9271 


0.5017 
0.5145 


1.6454 
1.6446 


1.6251 
1.6248 


0.5145 


1.8687 


1.8690 


1.9232 








0.5321 


1.8645 


1.8649 


1.9185 


0.5320 


1.6433 


1.6231 


0.6328 


1.8476 


1.8482 


1.8993 


0.6328 


1.6378 


1.6183 


1.6642 


1.8222 


1.8226 


1.8704 


1.0642 


1.6274 


1.6088 



Dispersion equation: 

n 2 - 1 = 2.27241A 2 /(A 2 - 0.023359) 
n 2 - 1 = 2.273955A 2 /(A 2 - 0.02333) 
n y 2 - 1 =2.44301 6A 2 /(A 2 - 0.025133) 
where A is in iim. 



Dispersion equation: 

n 2 - 1 = 1.6346A 2 /(A 2 - 0.010734) 
n 2 - 1 = 1.57256A 2 /(A 2 - 0.011346) 
where A is in /xm. 



520 Handbook of Lasers 



TABLE 18-4. REFRACTIVE INDICES {Continued) 



18.4.54 ZINC GERMANIUM PHOSPHIDE 

(ZnGeP 2 ) 

Room Temperature (Ref. 17) 



Wavelength 






(jjm) 


n a 


M e 


0.64 


3.5052 


3.5802 


0.66 


3.4756 


3.5467 


0.68 


3.4477 


3.5160 


0.70 


3.4233 


3.4885 


0.75 


3.3730 


3.4324 


0.80 


3.3357 


3.3915 


0.85 


3.3063 


3.3593 


0.90 


3.2830 


3.3336 


0.95 


3.2638 


3.3124 


1.00 


3.2478 


3.2954 


1.10 


3.2232 


3.2688 


1.20 


3.2054 


3.2493 


1.30 


3.1924 


3.2346 


1.40 


3.1820 


3.2244 


1.60 


3.1666 


3.2077 


1.80 


3.1562 


3.1965 


2.00 


3.1490 


3.1889 


2.20 


3.1433 


3.1829 


2.40 


3.1388 


3.1780 


2.60 


3.1357 


3.1745 


2.80 


3.1327 


3.1717 


3.00 


3.1304 


3.1693 


3.20 


3.1284 


3.1671 


3.40 


3.1263 


3.1647 


3.60 


3.1257 


3.1632 


3.80 


3.1237 


3.1616 


4.00 


3.1223 


3.1608 


4.20 


3.1209 


3.1595 


4.50 


3.1186 


3.1561 


4.70 


3.1174 


3.1549 


5.00 


3.1149 


3.1533 


5.50 


3.1131 


3.1518 


6.00 


3.1101 


3.1480 


6.50 


3.1057 


3.1445 


7.00 


3.1040 


3.1420 


7.50 


3.0994 


3.1378 


8.00 


3.0961 


3.1350 


8.50 


3.0919 


3.1311 


9.00 


3.0880 


3.1272 


9.50 


3.0836 


3.1231 


10.00 


3.0788 


3.1183 


10.50 


3.0738 


3.1137 


11.00 


3.0689 


3.1087 


11.50 


3.0623 


3.1008 


12.00 


3.0552 


3.0949 



18.4.55 ZINC OXIDE 

(ZnO) 
Room Temperature {Ref. 12) 



Wavelength 






(/mi) 


"o 


n e 


0.45 


2.1058 


2.1231 


0.50 


2.0511 


2.0681 


0.60 


1.9985 


2.0147 


0.70 


1.9735 


1.9897 


0.80 


1.9597 


1.9752 


0.90 


1.9493 


1.9654 


1.00 


1.9435 


1.9589 


1.20 


1.9354 


1.9500 


1.40 


1.9298 


1.9429 


1.60 


1.9257 


1.9402 


1.80 


1.9226 


1.9370 


2.00 


1.9197 


1.9330 


2.20 


1.9173 


1.9313 


2.40 


1.9152 


1.9297 


2.60 


1.9128 


1.9265 


2.80 


1.9100 


1.9251 


3.00 


1.9075 


1.9214 


3.20 


1.9049 


1.9186 


3.40 


1.9022 


1.9160 


3.60 


1.8994 


1.9127 


3.80 


1.8964 


1.9101 


4.00 


1.8891 


1.9068 



18.4.56 ZINC SELENIDE 

(ZnSe) 
Room Temperature (Ref. 60) 



Wavelength 




(jj-va) 


n 


0.589 


2.61 


1.0 


2.48 


1.5 


2.45 


2.0 


2.44 



Dispersion equation: 

n 2 — 1 = 2.855+ 2.045A 2 /(A 2 - 0.109), 
where A is in /xm. 



18 Non-Linear Optical Materials 
TABLE 18-4. REFRACTIVE INDICES {Continued) 



521 



18.4.57a ZINC SULFIDE (ZnS) 
Room Temperature (Ref 5) 



Wavelength 






(jjum) 


n„ 


n e 


0.3600 


2.705 


2.709 


0.3750 


2.637 


2.640 


0.4000 


2.560 


2.564 


0.4100 


2.539 


2.544 


0.4200 


2.522 


2.525 


0.4250 


2.511 


2.514 


0.4300 


2.502 


2.505 


0.4400 


2.486 


2.488 


0.4500 


2.473 


2.477 


0.4600 


2.459 


2.463 


0.4700 


2.448 


2.453 


0.4750 


2.445 


2.449 


0.4800 


2.438 


2.443 


0.4900 


2.428 


2.433 


0.5000 


2.421 


2.425 


0.5250 


2.402 


2.407 


0.5500 


2.386 


2.392 


0.5750 


2.375 


2.378 


0.6000 


2.363 


2.368 


0.6250 


2.354 


2.358 


0.6500 


2.346 


2.350 


0.6750 


2.339 


2.343 


0.7000 


2.332 


2.337 


0.8000 


2.324 


2.328 


0.9000 


2.310 


2.315 


1.000 


2.301 


2.303 


1.200 


2.290 


2.294 


1.400 


2.285 


2.288 



18.4.57b ZINC SULFIDE (ZnS) 
Room Temperature (Ref 12) 



Wavelength 




(/Mm) 


n 


0.45 


2.4709 


0.50 


2.4208 


0.60 


2.3640 


0.70 


2.3333 


0.80 


2.3146 


0.90 


2.3026 


1.00 


2.2932 


1.10 




1.20 


2.2822 


1.40 


2.2762 


1.60 


2.2716 


1.80 


2.2680 


2.00 


2.2653 


2.20 


2.2637 


2.40 


2.2604 



18.4.58a ZINC TELLURIDE (ZnTe) 
Room Temperature (Ref. 60) 

Wavelength 

(/urn) n 



0.589 


3.06 


0.620 


3.00 


0.830 


2.84 


1.240 


2.76 


2.06 


2.71 


Dispersion equation : 




n 2 - 1 = 3.27 + 3.01A 2 /(A 2 - 0.142), 


where A is in /*m. 





18.4.58b ZINC TELLURIDE (ZnTe) 
25° C (Ref . 104) 



Wavelength 




(/xm) 


n 


0.569 


3.111 


0.577 


3.085 


0.579 


3.079 


0.589 


3.054 


0.600 


3.035 


0.616 


3.005 


0.650 


2.962 


0.700 


2.913 


0.725 


2.893 


0.750 


2.879 


0.760 


2.871 


0.770 


2.866 


0.800 


2.853 


1.000 


2.790 


1.200 


2.758 


1.300 


2.748 


1.400 


2.741 


1.500 


2.734 


1.515 


2.734 



522 Handbook of Lasers 



REFERENCES TO TEXT 

1. P. A. Franken, A. E. Hill, C. W. Peters and G. Weinreich, "Generation of optical harmonics," Phys. Rev. Lett. 7, 118, 1961. 

2. M. Bass, P. A. Franken, J. F. Ward and G. Weinreich, " Optical rectification," Phys. Rev. Lett., 9, 446-448, 1962. 

3. P. A. Franken and J. F. Ward, "Optical harmonics and non-linear phenomena," Rev. Mod. Phys. 35, 23-29, 1963. 

4. J. A. Giordmaine and R. C. Miller, "Tunable coherent parametric oscillations in LiNb0 3 at optical frequencies," Phys. Rev. 
Lett., 14, 973-976, 1965. 

5. R. W. Terhune, P. D. Maker and C. M. Savage, " Optical harmonic generation in calcite," Phys. Rev. Lett., 8, 404-406, 1962. 

6. W. Kaiser and C. G. B. Garrett, "Two-photon excitation in CaF 2 :Eu 2+ ," Phys. Rev. Lett., 7, 229-231, 1961. 

7. G. Eckhardt, R. W. Hellwarth, F. J. McClung, S. E. Schwarz, D. Weiner and E. J. Woodbury, " Stimulated Raman scattering 
from organic liquids," Phys. Rev. Lett., 9, 455-457, 1962. 

8. R. Y. Chiao, C. H. Townes, and B. P. Stoicheff, "Stimulated Brillouin scattering and coherent generation of intense hyper- 
sonic waves," Phys. Rev. Lett. 12, 592-595, 1964. 

9. D. I. Mash, V. V. Morozov, V. S. Starunov, and J. L. Fabelinski, "Stimulated scattering of light of the Rayleigh-line wing," 
JETPLett., 2, 22-27, July 1965. 

10. P. N. Butcher, "Non-linear optical phenomena," Bulletin 200, Engineering Experiment Station, Ohio State University, 
Columbus, 1965. 

11. N. Bloembergen, "Non-linear optics," New York: Benjamin, 1965. 

12. L. N. Ovander, "Non-linear optical effects in crystals," Soviet Phys. Uspekhi, 8, 337-359, November-December 1965. 

13. R. W. Minck, R. W. Terhune and C. C. Wang, "Non-linear optics," Appl. Optics. 5, 1595-1612, 1966. 

14. J. Ducuing, " Nonlinear optical processes," Proceedings of the International School of Physics " Enrico Fermi," Varenna, 
Italy, " Quantum Optics," Edited by R. J. Glauber, Academic Press, New York, 1969, p. 421-472. 

14a. G. D. Boyd, W. L. Bond and H. L. Carter, " Refractive index as a function of temperature in LiNb0 3 ," /. Appl. Phys., 
38, 1941, 1967. 

15. R. W. Terhune and P. D. Maker, " Non-linear optics " in " Lasers : a series of advances," Vol. 2, ed. by A. K. Levine, Marcel 
Dekker, New York, 1968, pp. 295-372. 

16. J. A. Armstrong, N. Bloembergen, J. Ducuing and P. S. Pershan, " Interactions between light waves in a nonlinear dielectric," 
Phys. Rev., 127, 1918-1939, 1962. 

17. S. Bhagvantam, "Crystal symmetry and physical properties," Academic Press, London and New York, 1966. 

18. J. F. Nye, "Physical properties of crystals," Oxford University Press, London, 1964. 

19. "Standards on piezoelectric crystals," Proc. IRE, 37, 1378, 1949. 

20. D. A. Kleinman, "Non-linear dielectric polarization in optical media," Phys. Rev. 126, 1977-1979, 1962. 

21. P. D. Maker, R. W. Terhune, M. Nisenoff and C. M. Savage, " Effects of dispersion and focusing on the production of optical 
harmonics," Phys. Rev. Lett. 8, 21-22, 1962. 

22. J. A. Giordmaine, "Mixing of light beams in crystals," Phys. Rev. Lett. 8, 19-20, 1962. 

23. M. V. Hobden, " Phase-matched second-harmonic generation in biaxial crystals," /. Appl. Phys. 38, 4365-4372, 1967. 

24. S. Singh, D. A. Draegert and J. E. Geusic, "Optical and ferroelectric properties of barium sodium niobate," Phys. Rev. D, 
2, October 1, 1970. 

25. S. Singh, W. A. Bonner, J. R. Potopowicz and L. G. Van Uitert, "Non-linear optical susceptibility of lithium formate mono- 
hydrate," Appl. Phys. Lett., 17, 292-294, 1970. 

26. D. A. Kleinman, "Theory of second harmonic generation of light," Phys. Rev. 128, 1761-1775, 1962. 

27. G. D. Boyd, A. Ashkin, J. M. Dziedzic and D. A. Kleinman, " Second harmonic generation of light with double refraction," 
Phys. Rev. 137, A1305-A1320, 1965. 

28. G. D. Boyd and D. A. Kleinman, " Parametric interaction of focused Gaussian light beams," /. Appl. Phys. 39, 3597-3639, 
1968. 

29. T. J. Nelson, "Digital light deflection," Bell System Tech. J. 43, 821-845, May 1964. 

30. G. D. Boyd, A. Ashkin, J. M. Dziedzic and D. A. Kleinman, " SHG of light with double refraction," Phys. Rev. 137, A1305- 
A1320, 1965. 

31. D. A. Kleinman, A. Ashkin and G. D. Boyd, " Second harmonic generation of light by focused laser beams," Phys. Rev. 145, 
338-379, 1966. 

32. R. C. Miller, G. D. Boyd and A. Savage, "Non-linear optical interactions in LiNb0 3 without double refraction," Appl. Phys. 
Lett. 6, 77-79, 1965. 

33. R. W. Terhune, P. D. Maker and C. M. Savage, Appl. Phys. Lett. 2, 54, 1963. 

34. A. Ashkin, G. D. Boyd and J. M. Dziedzic, " Observation of continuous optical harmonic generation with gas masers," 
Phys. Rev. Lett. 11, 14-17, 1963. 

35. G. E. Francois, " CW measurement of the optical nonlinearity of ammonium dihydrogen phosphate," Phys. Rev. 143, 597-600, 
1966. 

36. J. E. Bjorkholm and A. E. Siegman, "Accurate cw measurements of optical second-harmonic generation in ammonium 
dihydrogen phosphate and calcite," Phys. Rev. 154, 851-860, 1967. 

37. R. C. Miller, D. A. Kleinman and A. Savage, " Quantitative studies of optical harmonic generation in CdS, BaTi0 3 and 
KH 2 P0 4 type crystals," Phys. Rev. Lett., 11, 146-149, 1963. 

38. J. Jerphagnon and S. K. Kurtz, " Maker fringes: A detailed comparison of theory and experiment for isotropic and uniaxial 
crystals," /. Appl. Phys., 41, 1667-1681, 1970. 

39. R. C. Miller and W. A. Nordland, " Relative signs of non-linear optical coefficients of polar crystals," Appl. Phys. Lett., 16, 
174-176, 1970. 

40. J. Ducuing and N. Bloembergen, " Observation of reflected light harmonics at the boundary of piezoelectric crystals," Phys. 
Rev. Lett., 10, 474-476, 1963. 

41. N. Bloembergen, "Second harmonic reflected light," Optica Acta, 13, 311-322, 1966. 

42. R. L. Byer and S. E. Harris, "Power and bandwidth of spontaneous parametric emission," Phys. Rev. 168, 1064-1068, 1968. 

43. A. J. Campillo and C. L. Lang, "Spontaneous parametric scattering of light in LiI0 3 ", Appl. Phys. Lett., 16, 242-244, 
1970. 

44. R. C. Miller, "Optical second harmonic generation in piezoelectric crystals," Appl. Phys. Lett., 15, 17-19, 1964. 

45. P. N. Butcher and T. P. McLean, "The non-linear constitutive relation in solids at optical frequencies," Proc. Phys. Soc. 18, 
219, 1963. 

46. P. L. Kelly, "Non-linear effects in solids," /. Phys. Chem. Solids, 24, 607, 1963. 

47. H. Cheng and P. B. Miller, "Non-linear optical theory in solids," Phys. Rev. 134, A683, 1964. 

48. J. F. Ward, "Calculation of non-linear optical susceptibilities," Rev. Mod. Phys. 37, 1, 1965. 



18 Non-Linear Optical Materials 523 

49. S. S. Jha and N. Bloembergen, "Non-linear optical coefficients in Group IV and III-V semiconductors," IEEE J. Quant. 
' Electr. QE-4, 670-673, 1968. 

50. F. N. H. Robinson, " Non-linear optical coefficients," Bell System Tech. J. 46, 913-956 1967. 

51 C. Flytzanis and J. Ducuing, " Second order optical susceptibility of III-V compounds, Phys. Lett., 26A, 315-316, 1968. 

52. C. G. B. Garrett and F. N. H. Robinson, " Miller's phenomenological rule for computing non-linear susceptibilities, IEEE 
J. Quant. Electr., QE2, 328-329, 1966. . 

53. M. DiDomenico, Jr., and S. H. Wemple, "Calculations of the non-linear optical tensor coefficients in oxygen-octahedra 
' ferroelectrics," Appl. Phys. Lett., 12, 352-355, 1968. ., , U1 , 71 , 

54. C. R. Jeggo and G. D. Boyd, " Nonlinear optical polarizability of the niobium— oxygen bond, /. Appl. Phys. 41, 1 uv-l /42, 

55. F. N. H. Robinson, " Relations between the components of the non-linear polarizability tensor in cubic and hexagonal II- VI 
' compounds," Phys. Lett. 26A, 435-436, 1968. . 

56. B. F. Levine, " Electrodynamical bond-charge calculation of non-linear optical susceptibilities, Phys. Rev. Lett. 22, 78 /- /yu, 

57. S. H. Wemple and M. DiDomenico, Jr., " Electro-optic phenomena in crystalline solids," in "Applied Solid State Science," 
Vol. 3 (R. Wolfe, Editor), Academic Press, New York, to be published. 

58 R Bechmann and S. R. Kurtz, " Second harmonic generation of light in crystalline solids," Landolt-Bornstein Numerical 
' Data and Functional Relationships, edited by K. H. Hellwege (New Series, Group I, Vol. 1, Springer- Verlag, Berlin, Germany, 
1969). 



REFERENCES TO TABLES 

1. A. Ashkin, G. D. Boyd and J. M. Dziedzic, "Observation of continuous optical harmonic generation with gas masers," 
' Phys. Rev. Lett. 11, 14-17,1963. . 

2. "American Institute of Physics Handbook, Second Edition," Dwight E. Gray, Co-ordinating Editor, McGraw-Hill Book 
Company, Inc., New York, 1963. 

3. J. G. Bergman, Jr., J. H. McFee and G. R. Crane, "Nonlinear optical properties of CdHg(SCN) 4 and ZnHg(SCN) 4 , Mat. 
' Res. Bull. 5, 913-917, November 1970. . . , . ... 

4. J. G. Bergman, Jr., J. H. McFee and G. R. Crane, " Pyroelectricity and optical second harmonic generation in polyvinylidene 
fluoride films," to be published. 

5. T. M. Bieniewski and S. J. Czyzak, " Refractive indexes of single hexagonal ZnS and CdS crystals, /. Opt. Soc. Amer., 53, 
495_497 1963. 

6. J. E. Bjorkholm, " Relative measurements of the optical nonlinearities of KDP, ADP, LiNb0 3 and a-HI0 3 ," IEEE J. Quant. 
Electr QE-4, 970-972, 1968 and J. E. Bjorkholm, Correction to "Relative measurement of the optical nonlinearities of 
KDP, ADP, LiNb0 3 and a-HI0 3 ," IEEE. J. Quant. Electr., QE-5, 260, 1969. 

7. J. E. Bjorkholm and A. E. Siegman, "Accurate cw measurements of optical second harmonic generation in ammonium 
dihydrogen phosphate and calcite," Phys. Rev., 154, 851-60, 1967. 

8. J. E. Bjorkholm, "Relative signs of the optical nonlinear coefficients d 31 and d 22 in LiNb0 3 ," Appl. Phys. Lett. 13, 36-37, 

!968. , . , , . 

9. N. Bloembergen, R. K. Chang, J. Ducuing and P. Lallemand, Proceedings of the seventh international conference on the physics 
of semiconductors (Dunod Cie, Paris, 1964), p. 121. 

10. N. Bloembergen, "Nonlinear optics," Benjamin Inc., New York, 1965. 

11. D. M. Boggett and A. F. Gibson, "Second harmonic generation in proustite." Phys. Lett. 28 A, 33, 1968. 

12. W. L. Bond, " Measurement of the refractive indices of several crystals," /. Appl. Phys. 36, 1674-77, 1965. 

13. W. L. Bond, G. D. Boyd and H. L. Carter, Jr., " Refractive indices of HgS (cinnabar) between 0.62 and 1 1 /a," J. Appl. Phys. 38, 
4090-91, 1967. , ti 

14. G. D. Boyd, R. C. Miller, K. Nassau, W. L. Bond and A. Savage, "LiNb0 3 : An efficient phase matchable nonlinear optical 
material," Appl. Phys. Lett. 5, TbA-llb, 1964. 

15. G. D. Boyd, T. J. Bridges and E. G. Burkhardt, "Up conversion of 10.6/u. radiation to the visible and second harmonic 
' generation in HgS," IEEE J. Quant. Electr., QE-4, 515-519, 1968. 

16. G. D. Boyd and D. A. Kleinman, "Parametric interaction of focused Gaussian light beams." J. Appl. Phys. 39, 3597-3639, 

17. G. D. Boyd, E. Buehler and E. G. Storz, " Linear and nonlinear optical properties of ZnGeP 2 and CdSe," Appl. Phys. Lett. 18, 
301-304, 1971. JC ntc 

18 R Braunstein and N. Ockman, " Interactions of coherent optical radiation with solids." Final report prepared for the Office 
of Naval Research, Department of the Navy, Washington, D.C. Contract #NONR-4128100 Arpa Order #306-62, August 

19. R. L. Byer and S. E. Harris, "Power and bandwidth of spontaneous parametric emission," Phys. Rev., 168, 1064-1068, 
1968. 

20. R. S. Caldwell, Special report, Contract DA36-039-SC-71131, Purdue University, Dept. of Physics, January 1958. 

21. A. J. Campillo and C. L. Tang, " Spontaneous parametric scattering of light in LiI0 3 ," Appl. Phys. Lett. 16, 242-244, 1970.^ 

22. S. Chandrasekhar and M. S. Madhav, "Optical rotatory dispersion of crystals of sodium chlorate and sodium bromate," 
Acta Cryst. 23, 911-913, 1967. 

23. S. Chandrasekhar, "Optical rotatory dispersion of crystals," Proc. Roy. Soc, A259, 531-553, 1961. 

24. R. K. Chang, J. Ducuing and N. Bloembergen, "Dispersion of the optical nonlinearity in semiconductors," Phys. Rev. Lett. 
15, 415-418, 'l965. . ,_,._, „ rppp r 

25. D. Chemla, P. Kupecek, C. Schwartz, C. Schwab and A. Goltzene, "Nonlinear properties of cuprous halides, IEEE J. 
Quant. Electr. ££-7, 126-132, 1971. 

26. D. S. Chemla, P. J. Kupecek, D. S. Robertson and R. C. Smith, " Silver thiogallate, a new material with potential for infra-red 
devices," Optics Communications, 3, 29-31, March 1971. 

27. G. F. Dobrazhanski, M. P. Golovei and G. I. Kosourov, " Second harmonic generation in the crystal BeS0 4 • 4H 2 0," 
Zh. E.T.F. Pis Red, 10, 263-265, 20 September 1969. 

28. J. D. Feichtner, R. Johannes and G. W. Roland, " Growth and optical properties of single crystal pyrargynte (Ag 3 SbS 3 )," 
Appl. Optics, 9, 1716-1717, 1970. 

29. G. E. Francois, "CW measurement of the optical nonlinearity of ammonium dihydrogen phosphate," Phys. Rev., 143, 597- 
600, 1966. 



524 Handbook of Lasers 

30. I. Gampel and F. M. Johnson, "Index of refraction of single-crystal selenium," /. Opt. Soc. Amer. 59, 72-73, 1969. 

31. W. B. Gandrud, G. D. Boyd, J. H. McFee and F. H. Wehmeier, "Nonlinear optical properties of Ag 3 SbS3," Appl. Phys. 
Lett. 16, 59-61, 1970. 

32. M. Garfinkel and W. F. Engeler, "Sum frequencies and harmonic generation in GaAs lasers," Appl. Phys. Lett. 3, 178-180, 
1963. 

33. J. E. Geusic, H. J. Levinstein, J. J. Rubin, S. Singh and L. G. Van Uitert, " The nonlinear optical properties of Ba 2 NaNb 5 15 ," 
Appl. Phys. Lett. 11, 269-271, 1967. 

34. J. E. Geusic, H. J. Levinstein, J. J. Rubin, S. Singh and L. G. Van Uitert. Erratum to "The nonlinear optical properties of 
Ba 2 NaNb 5 15 , Appl. Phys. Lett. 11, 269-271, 1967." Appl. Phys. Lett. 12, 224, 1968. 

35. W. F. Hagen and P. C. Magnante, "Efficient second harmonic generation with diffraction limited and high spectral radiance 
Nd-glass lasers," /. Appl. Phys. 40, 219-224, 1969. 

36. G. H. Heilmeier, N. Ockman, R. Braunstein and D. A. Kramer, " Relationship between optical second harmonic generation 
and the electro-optic effect in the molecular crystal hexamine," Appl. Phys. Lett. 5, 229-230, 1964. 

37. S. Hirotsu, T. Yanaei and S. Sawada, " Refractive indices of NaN0 2 and anisotropic polarizability of N0 2 ~," J. Phys. Soc. 
Japan, 25, 799-807, 1968. 

38. M. V. Hobden, " Phase-matched second harmonic generation in biaxial crystals," /. Appl. Phys., 38, 4365-4372, 1967. 

39. M. V. Hobden, " Optical activity in a nonenantiomorphous crystal: AgGaS 2 ," Acta Cryst. A24, 676-680, 1968. 

40. M. V. Hobden, D. S. Robertson, P. H. Davies, K. Hulme, J. Warner and J. Midwinter, " Properties of a phase-matchable 
nonlinear optical crystal: potassium dithionate," Phys. Lett. 22, 65-66, 1966. 

41. M. V. Hobden and J. Warner, "Temperature dependence of the refractive indices of pure lithium niobate," Phys. Lett. 22, 
243-244, 1966. 

42. K. F. Hulme, O'Jones, P. H. Davies and M. V. Hobden, " Synthetic proustite (Ag 3 AsS 3 ) : A new crystal for optical mixing," 
Appl. Phys. Lett. 10, 133-135, 1967. 

43. A. N. Izrailenko, R. Yu Orlov and V. A. Koptsik, "Ammonium oxalate — A new nonlinear optical material," Sov. Phys. 
Crystallogr. 13, 136, July-August 1968. 

44. J. Jerphagnon, M. Sourbe and E. Batifol, "Addition dans la tellure de deux rayonnements produits par un laser C0 2 ," 
C. R. Acad. Sci. Paris, 263, 1067-1070, 1966. 

45. J. Jerphagnon, E. Batifol et M. Sourbe, " Generation de second harmonique d'un rayonnement laser dans le selenium et 
dans un alliage tellure-seleneum," C. R. Acad. Sci. Paris, 265, 400-402, 1967. 

46. J. Jerphagnon, E. Batifol, G. Tsoucaris, et M. Sourbe, " Generation de second harmonique dans le cinabre." C. R. Acad. Sci. 
Paris, Series B, 265, 495-497, 1967. 

47. J. Jerphagnon, C. Schwab and D. Chemla, " Generation de second harmonique dans le chlorure cuivreux." C. R. Acad. Sci. 
(Paris), 265B, 1032, 1967. 

48. J. Jerphagnon, Ann. Telecomm. 23, 203, 1968. 

49. J. Jerphagnon and S. K. Kurtz, " Optical nonlinear susceptibilities: accurate relative values for quartz, ammonium dihydrogen 
phosphate, and potassium dihydrogen phosphate." Phys. Rev. IB, 1738-1744, 1970. 

50. J. Jerphagnon, " Optical nonlinear susceptibilities of lithium iodate." Appl. Phys. Lett. 16, 298-299, 1970. 

51. J. Jerphagnon and H. W. Newkirk, " Optical nonlinear susceptibilities of beryllium oxide." Appl. Phys. Lett. 18, 245-247, 1971. 

52. J. Jerphagnon, " Optical second harmonic generation in isocyclic and heterocyclic organic compounds " to be published. 

53. W. D. Johnston and I. P. Kaminow, "Contributions to optical nonlinearity in GaAs as determined from Raman scattering 
efficiencies." Phys. Rev. 188, 1209-1210, 1969. 

54. D. A. Kleinman and R. C. Miller, " Dependence of second harmonic generation on the position of the focus," Phys. Rev. 148, 
302-312, 1966. 

55. S. K. Kurtz and T. T. Perry, "A powder technique for the evaluation of nonlinear optical materials," J. Appl. Phys. 39, 3798- 
3813, 1968. 

56. S. K. Kurtz, T. T. Perry and J. G. Bergman, Jr., " a-Iodic acid: A solution grown crystal for nonlinear optical studies and 
applications, Appl. Phys. Lett. 12, 186-188, 1968. 

57. Landolf-Bornstein, Optische Konstanten, Springer-verlag, Berlin, II Band, 8 Teil, 1962, 2-43 to 2-397. 

58. P. V. Lenzo, E. G. Spencer and J. P. Remeika, " Some optical properties of lithium gallium oxide," Appl. Optics, 4, 1036-1037, 

59. P. D. Maker and R. W. Terhune, " Study of optical effects due to an induced polarization third order in the electric field 
strength." Phys. Rev. 137 A, 801-818, 1965. 

60. D. T. F. Marple, " Refractive index of ZnSe, ZnTe and CdTe," J. Appl. Phys. 35, 539-542, 1964. 

61. D. T. F. Marple, " Refractive index of GaAs," /. Appl. Phys. 35, 1941-42, 1964. 

62. J. H. McFee, G. D. Boyd and P. H. Schmidt, "Redetermination of the nonlinear optical coefficients of Te and GaAs," Appl. 
Phys. Lett. 17, 57-59, 1970. 

63. D. H. McMahon and A. R. Franklin, "Laser focusing effects on second harmonic generation in ADP," Appl. Phys. Lett. 
6, 14-16, 1965. 

64. D. H. McMahon, " Quantitative nonlinear optical sum frequency experiments using incoherent light,' /. Appl. Phys. 37, 
4832-39, 1966. . . 

65. R. C. Miller and A. Savage, "Harmonic generation and mixing of CaWo 4 : Nd 3+ and ruby pulsed laser beams in piezo- 
electric crystals," Phys. Rev. 128, 21 75-79, 1962. 

66. R. C. Miller, D. A. Kleinman and A. Savage, " Quantitative studies of optical harmonic generation in CdS, BaTi0 3 and 
KH 2 P0 4 type crystals," Phys. Rev. Lett. 11, 146-148, 1963, and private communication. 

67. R. C. Miller, "Optical second harmonic generation in piezoelectric crystals," Appl. Phys. Lett. 5, 17-19, 1964, and private 
communication. 

68. R. C. Miller, " Optical harmonic generation in single crystal BaTi0 3 ," Phys. Rev. 134A, 1313-1319, 1964. 

69. R. C. Miller and A. Savage, "Temperature dependence of the optical properties of ferroelectric LiNb0 3 and LiTa0 3 ," Appl. 
Phys. Lett. 9, 169-171, 1966. 

70. R. C. Miller and W. A. Nordland, "Absolute signs of nonlinear optical coefficients of polar crystals." Optics Communications, 
1, 400^K)2, March 1970. 

71. R. C. Miller, W. A. Nordland, E. D. Kolb and W. L. Bond, "Nonlinear optical properties of lithium gallium oxide, /. Appl. 
Phys. ¥1,3008-3011, 1970. . . 

72. R. C. Miller and W. A. Nordland, "Absolute signs of second harmonic generation coefficients of piezoelectric crystals, 

to be published. n. \ » t u 

73. R. C. Miller, W. A. Nordland and K. Nassau, "Nonlinear optical properties of Gd 2 (Mo0 4 ) 3 and Tb 2 (Mo0 4 ) 3 , To be 

74. R. C. Miller, S. C. Abrahams, J. L. Bernstein, W. A. Nordland and E. H. Turner, "Absolute signs of the second harmonic 
generation, electro-optic, and piezoelectric coefficients of CuCl and ZnS," to be published. 

75 A Mooradian and A. L. McWhorter, " Light scattering from plasmons and phonons in GaAs," International conference on 
light scattering in solids." New York University, 1968, edited by G. B. Wright (Springer, New York, 1969). 



18 Non-Linear Optical Materials 525 

76. F. R. Nash, J. G. Bergman, Jr., G. D. Boyd and E. H. Turner, " Optical nonlinearities in LiI0 3 ," /. Appl. Phys. 40, 5201- 
5206, 1969. . . 

77. G. Nath and S. Haussuhl, " Large nonlinear optical coefficient and phase-matched second harmonic generation in LiI0 3 . 
Appl. Phys. Lett. 14, 154-156, 1969. „ 

78. D. F. Nelson and E. H. Turner, "Electro-optic and piezoelectric coefficients and refractive index of gallium phosphide. 
/. Appl. Phys. 39, 3337-3343, 1968. 

79. H. W. Newkirk, D. K. Smith, and J. S. Kahn, " Synthetic Bromellite III— some optical properties," Am. Mineral, 51, 141-151, 
January-February 1966. 

80. W. A. Nordland, "Absolute signs of the nonlinear optical coefficients of KH 2 PO* ," To be published. 

81. M. Okada and S. Ieiri, " Kleinman's symmetry relation in nonlinear optical coefficient of LiI0 3 ," Phys. Lett. 34 A, 63-64, 1971. 

82. R. Yu Orlov, "Hippuric acid as a source of second harmonics in the optical range," Soviet Phys. — Crystallogr. 11, 410-411, 
Nov-Dec. 1966. 

83. C. K. N. Patel, "Efficient phase-matched harmonic generation in tellurium with a C0 2 laser at 10.6/li." Phys. Rev. Lett. 15, 
1027-30, 1965. 

84. C. K. N. Patel, " Optical harmonic generation in the infra-red using a Co 2 -laser," Phys. Rev. Lett. 16, 613-616, 1966. 

85. R. A. Phillips, "Temperature variation of the index of refraction of ADP, KDP and deuterated KDP," J. Opt. Soc. Amer., 56, 
629-632, 1966. 

86. H. J. Simon and N. Bloembergen, " Second harmonic light generation in crystals with natural optical activity," Phys. Rev., 
171, 1104-1114, 1968. 

87. S. Singh, D. A. Draegert and J. E. Guesic, " Optical and ferroelectric properties of barium sodium niobate," Phys. Rev., B2, 
2709, 2724, 1970. 

88. S. Singh, W. A. Bonner, J. R. Potopowicz and L. G. Van Uitert, "Nonlinear optical susceptibility of lithium formate mono- 
hydrate." Appl. Phys. Lett. 17, 292-294, 1970. 

89. S. Singh, J. R. Potopowicz, L. G. Van Uitert and S. H. Wemple, "Nonlinear optical properties of hexagonal silicon carbide," 
to be published. R. C. Miller — Private Communication. 

90. S. Singh — unpublished. 

91. S. Singh, J. R. Potopowicz, F. S. Chen, W. A. Bonner and L. G. Van Uitert, "Second harmonic coefficient, optical activity 
and temperature dependent refractive indices of LiI0 3 ," to be published. 

92. S. Singh, J. R. Potopowicz and R. Pawelek, " Second harmonic properties of tourmaline," to be published. 

93. S. Singh, S. H. Wemple, J. R. Potopowicz, I. Camlibel and M. DiDomenico, Jr., "Nonlinear optical susceptibilities of melt 
grown BaTi0 3 ," to be published. 

94. S. Singh, J. P. Remeika and J. R. Potopowicz, " Nonlinear optical susceptibilities of ferroelectric lead titanate," Opt. Soc. 
Amer. Spring Meeting, Tuscon, Arizona. April 1971. R. C. Miller— Private Communications. 

95. S. Singh and A. A. Ballman — unpublished. 

96. S. Singh, J. R. Potopowicz, W. A. Bonner and L. G. Van Uitert, " Nonlinear optical properties of rubidium dihydrogen 
phosphate," to be published. 

97. S. Singh, J. R. Potopowicz, W. A. Bonner and L. G. Van Uitert, "Nonlinear optical properties of ferroelastic Gd 2 (Mo0 4 ) 3 ," 
to be published. 

98. S. Singh, W. A. Bonner, J. R. Potopowicz and L. G. Van Uitert, "Nonlinear optical properties of lead niobate," Electro- 
chemical Soc. Meeting, Los Angeles. May 1970. R. C. Miller— Private Communication. 

99. S. Singh, J. R. Potopowicz, W. A. Bonner and L. G. Van Uitert, "Nonlinear optical properties of ferroelastic Tb 2 (Mo0 4 ) 3 ," 
to be published. 

100. S. Singh, W. A. Bonner, J. R. Potopowicz and L. G. Van Uitert, "Nonlinear optical properties of rf-threonine," to be 
published. 

101. S. Singh — unpublished. 

102. S. Singh and R. Pawelek — unpublished. 

103. S. Singh and R. Pawelek — unpublished. 

104. T. R. Sliker and J. M. Jost, "Linear electro-optic effect and refractive indices of cubic ZnTe," /. Opt. Soc. Amer. 56, 130- 
131, 1966. 

105. A. W. Smith, G. Burns and D. F. O'Kane, "Optical and ferroelectric properties of K x 'Na 1 _ x Ba 2 «Nb 5 15 ," /. Appl. 
Phys. 42, 250-255, 1971. 

106. A. Sonin, A. A. Filiminov and V. S. Suvorov, " Generation of the second harmonic of ruby laser radiation in some crystals," 
Sov. Phys— Solid State, 10, 1481-82, 1968. 

107. A. S. Sonin and V. S. Surovov, "Nonlinear optical properties of triglycine sulfate single crystals," Soviet Physics— Solid 
State, 9, 1437-38, 1967. 

108. R. A. Soref and H. W. Moos, "Optical second harmonic generation in ZnS-CdS and CdS-CdSe alloys," /. Appl. Phys. 35, 
2152-2158, 1964. 

109. W. Sturmer and U. Deserno, "Mercury thiocyanate complexes: efficient phase-matchable SHG in crystal class 10," Phys. 
Lett. 32A, 539-540, 1970. 

1 10. V. S. Suvorov, A. S. Sonin and I. S. Rez, " Some nonlinear optical properties of crystals of the KDP group." Sov. Physics 
JETP, 26, 33-37, January 1968. 

111. V. S. Suvorov and A. S. Sonin, "Nonlinear optical materials," Sov. Phys. — Crystallography, 11, 711-723, 1967. 

112. J. P. Vander Ziel and N. Bloembergen, "Temperature dependence of optical harmonic generation in KH 2 P0 4 ferro- 
electrics," Phys. Rev., 135, A1622-A1669, 1964. 

113. N. Van Tran, "Properties optiques nonlineares du tellure." L'Onde Electrique, 48, 965, 1967. 

114. L. G. Van Uitert, S. Singh, H. J. Levinstein, J. E. Geusic and W. A. Bonner, "A new and stable nonlinear optical material," 
Appl. Phys. Lett. 11, 161-163, 1967. 

115. L. G. Van Uitert, S. Singh, H. J. Levinstein, J. E. Guesic and W. A. Bonner, Erratum to "A new and stable nonlinear 
optical material, Appl. Phys. Lett. 11, 161-163, 1967." Appl. Phys. Lett. 12, 224, 1968. 

116. A. S. Vasilevskaya, M. F. Koldobskaya, L. G. Lamova, V. P. Popova, T. A. Regulskaya, I. S. Rez, Yu P. Sobesskn, A. S. 
Sonin and V. S. Suvorov, " Some physical properties of rubidium dihydrogen phosphate single crystals," Sov. Phys. — 
Crystallography, 12, 383-385, November-December 1967. 

117. A. N. Winchell, " The optical properties of organic compounds." Academic Press, New York 1 954. 

118. A. N. Winchell and H. Winchell, "The microscopic characters of artificial inorganic solid substances." Academic Press, 
New York, 1964. 

119. J. J. Wynne and N. Bloembergen, "Measurement of the lowest-order nonlinear susceptibility in III-V semiconductors by 
second harmonic generation with a C0 2 laser," Phys. Rev. 188, 121 1-1220, 1969. 

120. T. Yanagi, K. Iio, H. Hanadate and S. Sawada, " Study of phase transition of NaN0 2 by the second harmonic generation." 
J. Phys. Soc. Japan, 28, Supplement 1970. Proceedings of the second international meeting on ferroelectricity, 1969. 

121. F. Zernike, Jr., "Refractive indices of ammonium dihydrogen phosphate and potassium dihydrogen phosphate between 
2000 A and 1.5/*."/. Opt. Soc. Am. 54, 1215-20, 1964. 



Stimulated Raman Scattering (SRS) 



Fred M. Johnson 

Physics Department 

California State College 

Fullerton, California 92631 



In most high-power laser applications, the availability of polychromaticity would greatly enhance 
the use of the laser. Applications such as Lidar, spectroscopic remote sensing, and biophysics, among 
many others, virtually necessitate the availability of specific frequencies at high peak powers. The 
purpose of this chapter is to provide a simplified tool for the experimental scientist and application 
engineer in selecting the required compounds for modifying the Q-switched laser output, as well as 
stressing overall principles, techniques and limitations. The physical principles of Raman Scattering 
are described in chapters of basic texts 1 ,2,3 and in an excellent review article. 4 



GENERAL CONSIDERATIONS 

The properties of the primary laser source greatly affect SRS, particularly since its onset requires a 
threshold incident power density, minimum laser line width, a specific range of pulse width, and pre- 
ferably, but not necessarily, a single transverse mode. The commercial Q-switched ruby laser (6943 A) 
is generally adequate, but the Nd glass laser has to be Q-switched by chemical 5 rather than mechanical 
means to provide narrow enough laser line width. As a rule of thumb, incident powers of 10-100 M 
Watts are generally adequate. However, whether or not SRS is induced in any specific material depends 
on these considerations : The threshold onset for SRS has to be below that of other competing processes, 
such as e.g. two-photon absorption 6 and stimulated Brillouin scattering. 7 A list of materials in which 
SRS has been observed is shown in Table 19-1. The number of accessible SRS-shifted wavelengths can 
be greatly extended by utilizing the iterative and parametric properties of the stimulated Raman Scatter- 
ing process. 24 

m[v L ± «! v(A) ± n 2 v(B) + • • •] (cm -1 ) 

where v L is the fundamental laser frequency (in cm -1 ); n u n 2 are integers; A, B are typical Raman 
scatterers; v(A), v(B) are Raman frequency shifts (see Table 19-1); 

and m = 1 for normal operation 

m = 2 if the combination output is doubled in frequency by means of a tunable phase-matched, 
nonlinear optic crystal (such as e.g. KDP or lithium niobate) 

The liquids can be placed in quartz cells, typically 2 to 12 inches in length, and \ to 1 inch in 
diameter. If liquids A and B do not interact chemically, a single cell rather than two cells in tandem is 
preferable. 24 Windows should be of thick quartz or high quality optical glass. The laser beam should be 
either focused at the center of the cell or collimated into as narrow a beam as possible by means of an 
inverted telescopic optical system. Safety provisions should be made for liquid containment due to the 
inevitable breakage of cell windows as a result of a possible Brillouin effect. Raman scattering solids are 
invariably damaged subsequent to each laser exposure, hence are listed for the sake of completeness 
only. For additional Raman scatterers consult Ref. 25. For each molecule, a number of Raman vibra- 
tional frequencies are listed in Ref. 25. The most likely frequency shift to be excited via SRS corresponds 

526 



19 Stimulated Raman Scattering 527 



TABLE 19-1. SUBSTANCES FOUND TO EXHIBIT STIMULATED 

RAMAN EFFECT 



Substance 


Frequency 
shift 


Refer- 


Frequency 
Substance shift 


Refer- 




(cm" 1 ) 


ences 




(cm" 1 ) 


ences 


LIQUIDS 






LIQUIDS {continued) 






Bromoform 


222 


10 


1-Hexyne 


2116 


19 


Tetrachloroethylene 


447 


17 


o-Dichlorobenzene 


2202 


19 


Carbon tetrachloride 


460 


19 


Benzonitrile 


2229 


15 


Ethyl iodide 


497 


23 


Acetonitrile 


2250 


23 


Hexaflourobenzene 


515 


19 


1 ,2-Dimethylaniline 


2292 


19 


Bromoform 


539 


10 


Methylcyclohexane 


2817 


19 


Trichlorethylene 


640 


10 


Methanol 


2831 


10 


Carbon disulfide 


656 


10 


cis, trans 1,3-Dimethylcyclohexane 


2844 


17 


Chloroform 


667 


10 


Tetrahydrofuran 


2849 


15 


o-Xylene 


730 


9 


Cyclohexane 


2852 


8,10 


a-Dimethylphenethylamine 


836 


16 


cis- 1 ,2-Dimethylcyclohexane 


2854 


17 


Dioxane 


836 


10 


a-Dimethylphenethylamine 


2856 


16 


Morpholine 


841 


19 


Dioxane 


2856 


10 


Thiophenol 


916 


19 


Cyclohexane 


2863 


8,10 


Nitromethane 


927 


19 


Cyclohexanone 


2863 


9 


Deuterated benzene 


944 


8 


cis, trans-l ,3-Dimethylcyclohexane 


2870 


17 


Cumene 


990 


19 


cis-l ,4-Dimethylcyclohexane 


2873 


17 


1 ,3-Dibromobenzene 


990 


17 


Cyclohexane 


2884 


8,10 


Benzene 


992 


8,10 


Dichloromethane 


2902 


19 


Pyridine 


992 


8 


Morpholine 


2902 


19 


Aniline 


997 


15 


2-Octene 


2908 


17 


Styrene 


998 


11,15 


2,3-Dimethyl-l,5-hexadiene 


2910 


17 


/n-Toluidine 


999 


19 


Limonene 


2910 


16 


Bromobenzene 


1000 


15 


o-Xylene 


2913 


9 


Chlorobenzene 


1001 


19 


1-Hexyne 


2915 


9 


Benzonitrile 


1002 


15 


cw-2-Heptene 


2920 


17 


terf-Butylbenzene 


1002 


17 


Mesitylene 


2920 


16 


Ethylbenzene 


1002 


9 


2-Bromopropane 


2920 


17 


Toluene 


1004 


8,10 


Acetone 


2921 


9,10 


Fluorobenzene 


1012 


12 


Ethanol 


2921 


10 


y-Picoline 


1016 


19 


Carvone 


2922 


16 


m-Cresol 


1029 


19 


cis-l ,2-Dimethylcyclohexane 


2927 


17 


m-Dichlorobenzene 


1030 


19 


Dimethylformamide 


2930 


10 


1 -Fluoro-2-chlorobenzene 


1030 


17 


2-Chloro-2-methylbutane 


2931 


17 


Iodobenzene 


1070 


19 


2-Octene 


2931 


17 


Benzoyl chloride 


1086 


19 


cis, fra«.s-l,3-Dimethylcyclohexane 


2931 


17 


Benzaldehyde 


1086 


19 


m-Xylene 


2933 


9 


Anisole 


1097 


19 


1,2-Diethyl tartrate 


2933 


16 


Pyrrole 


1178 


19 


o-Xylene 


2933 


9 


Furan 


1180 


19 


Piperidine 


2933 


9 


Styrene 


1315 


11,15 


1 ,2-Diethylbenzene 


2934 


17 


Nitrobenzene 


1344 


8, 10 


2-Chloro-2-methylbutene 


2935 


17 


1 -Br omonaphthalene 


1368 


8 


1 -Br omopropane 


2935 


17 


1 -Chloronaphthalene 


1368 


15 


Piperidine 


2936 


9 


2-Ethylnaphthalene 


1381 


17 


Tetrahydrofuran 


2939 


15 


/n-Nitrotoluene 


1389 


19 


Piperidine 


2940 


9 


Quinoline 


1427 


19 


Cyclohexanone 


2945 


9 


Bromocyclohexane 


1438 


23 


2-Nitropropane 


2948 


17 


Furan 


1522 


19 


1,2-Diethyl carbonate 


2955 


19 


Methyl salicylate 


1612 


19 


1 ,2-Dichloroethane 


2956 


19 


Cinnamaldehyde 


1624 


15 


trans-Dichl oroethylene 


2956 


10 


Styrene 


1629 


11,15 


1 -Br omopropane 


2962 


17 


3-Methylbutadiene 


1638 


14 


2-Chloro-2-methylbutane 


2962 


17 


Pentadiene 


1655 


14 


a-Dimethylphenethylamine 


2967 


16 


Isoprene 


1792 


16 


Dioxane 


2967 


10 



528 Handbook of Lasers 

TABLE 19-1. SUBSTANCES FOUND TO EXHIBIT STIMULATED 
RAMAN EFFECT (Continued) 



Substance 


Frequency 
shift 


Refer- 


Substance 


Frequency 
shift 


Refer- 




(cm" 1 ) 


ences 




(cm" 1 ) 


ences 


LIQUIDS {continued) 






SOLIDS 






Cyclohexanol 


2982 


19 


Quartz 


128 


18 


Cyclopentane 


2982 


19 


Lithium niobate 


152 


22 


Cyclopentanol 


2982 


19 


a Sulfur 


216 


15 


Bromocyclopentane 


2982 


19 


Lithium niobate 


248 


21,22 


<?-Dichlorobenzene 


2982 


19 


Quartz 


466 


18 


jP-Chlorotoluene 


2982 


19 


a Sulfur 


470 


15 


a-Picoline 


2982 


19 


Lithium niobate 


628 


21,22 


^-Xylene 


2988 


9 


Calcium tungstate 


911 


15 


o-Xylene 


2992 


9 


Stilbene 


997 


16 


Dibutyl-phthalate 


2992 


19 


Polystyrene 


1001 


10 


1,1,1 -Trichloroethane 


3018 


10 


Calcite 


1084 


10 


Ethylene chlorhydrin 


3022 


19 


Diamond 


1332 


15 


Isophorone 


3022 


19 


Naphthalene 


1380 


15 


Nitrosodimethylamine 


3022 


19 


Stilbene 


1591 


16 


Propylene glycol 


3022 


19 


Triglycine sulfate 


2422 


19 


Cyclohexane 


3038 


19 


Triglycine sulfate 


2702 


19 


Styrene 


3056 


11,15 


Triglycine sulfate 


3022 


19 


Benzene 


3064 


8,10 


Polystyrene 


3054 


10 


terf -Butyl benzene 


3064 


17 








l-Fluoro-2-chlorobenzene 


3084 
3090 


17 
19 








Turpentine 








Pseudocumene 


3093 


19 


GASES 






Acetic acid 


3162 
3162 


19 
19 








Acetonylacetone 








Methyl raethacrylate 


3162 


19 


Oxygen 
Potassium vapor 


1552 

2721 


15 
20 


y-Picoline 


3182 


19 


Methane 


2916 


13 


Aniline 


3300 


15 


Deuterium 


2991 


13 


Water 


3651 


19 


Hydrogen 


4155 


13 



to the strongest and narrowest line, apart from the general requirement that the excitation should cor- 
respond to a totally symmetric vibration. 

The most satisfactory Raman scattering medium is undoubtedly a gas such as hydrogen, in view of 
its chemical stability and large vibrational shifts. 24 Gas mixtures are also easily handled. A convenient 
and safe high pressure gas cell, including all necessary optics and compatible with existing lasers, is 
produced commercially by Geoscience Instruments. 26 Such a Raman cell should outlast the life of the 
laser. If a very large number of coherent lines are required covering the whole spectrum from UV to IR, 
it is suggested that one consult a technique described in Ref. 27, whereby coherent rotational as well as 
vibrational modes of the hydrogen molecule are excited, giving rise to the lines listed in Table 19-2. 
The general formula is : 



v = v L + mv Q(1) + nv S(0) + pv sw (cm 



-l 



(where m,n,p = 0, +1, ±2, — ) 



and 



(p = or ± 1) 



v = mv Q(1) +/>v S(1) -v L 

The special conditions necessary to excite this extensive spectrum are described in Ref. 27. The key 
requirement is a narrow line-width, 1.058 fi, giant, pulsed laser source, produced e.g. by an oscillator- 
amplifier combination. Gas pressure and power density are also critical. 28 



19 Stimulated Raman Scattering 529 

TABLE 19-2. COMBINATION 

ROTATIONAL-VIBRATIONAL 

RAMAN SPECTRUM OF 

HYDROGEN 

PRODUCED BY USING SPECIAL 1.058|i 
EXCITATION 

Partial Listing 27 

AAA AAA 

3373 3663 3783 3930 5267 6458 

3441 3670 3801 3937 5280 6488 

3447 3676 3828 4820 5449 6505 

3518 3701 3835 4944 5629 6660 

3523 3718 3842 4961 5822 6713 

3586 3733 3848 4972 6028 6764 
3592 3744 3870 5092 6044 6873 
3598 3750 3888 5109 6222 6931 
3632 3757 3916 5121 6249 7024 
3638 3764 3923 5248 6267 7044 

7348 

BASIC EXPRESSIONS 1 4 DESCRIBING THE RAMAN SCATTERING 
PROCESSES 

Intensity of scattered light per molecule: 

/oc(v L + v kB ) 4 |C kB | 2 
where v L = laser frequency 

v kn = frequency corresponding to energy difference between initial state k and final state n 
C kn = complex amplitude of induced dipole moment 

A = amplitude of laser electric field 
The components of the scattering tensor c kH are given in Cartesian coordinates by 



-i?{ 



<*|itf ,|r)<r|Ar,lii) + <k\M p \rXr\M a \n» 

Vrk ~ Vl V rn + V L j 



(c Pa ) k „ = t i r p + 



The matrix elements <A:|M|r> and <r|Af|n> represent the amplitudes of the electric moment for the 
transitions k -+ r and r -*• n respectively, with r designating the intermediate state. 

Raman Gain of Stokes wave (s) Expressions: (Ref. 1, p. 235) 

9s = -} ( m ) 

s refers to Stokes wave 

i refers to incident wave, i.e. laser wave 
Xr is complex part of Raman susceptibility 
X s = free space wavelength of Stokes radiation 

/. = ^(8 c\ E t \ 2 = power per unit area in incident wave 

rj is refractive index 

Total Raman scattering cross-section 

^ _ lGx*h(Aa>Jn 8 b&(<D v = Q)] 
3eori t X t X*N v 

Typical value a c = 5.6 x 10 -29 cm 2 for 992 cm -1 line in benzene 



530 Handbook of Lasers 

SELF-FOCUSING (Ref. 1, p. 255) 

This phenomenon is observed in most Raman active liquids. It manifests itself by a substantial 
increase in Stokes gain over the calculated theoretical results. It results from the fact that the index of 
refraction, rj, is higher in regions of high optical intensity. Hence lens effects are produced, resulting in 
intense filaments 2-100 microns in diameter. The net effect is to decrease the laser threshold power for 
onset of SRS. For practical applications however, these narrow filaments result in possible deleterious 
effects, such as (1) competing nonlinear optic phenomena, such as Brillouin scattering; (2) absorption 
via 2 photon process; (3) excessive beam divergence on emergence from cell; (4) possible damage to cell 
windows; and (5) non-uniform and random filamentary positions on successive pulses. Hence gases are 
to be preferred, if at all possible. 



REFERENCES 

1. R. H. Pantell and H. E. Puthoff, " Fundamentals of Quantum Electronics," John Wiley & Sons, Inc., 1969. 

2. N. Bloembergen, "Nonlinear Optics," Benjamin Co., Inc., New York, 1965. 

3. A. Yariv, "Quantum Electronics," John Wiley & Sons, Inc., New York, 1967. 

4. G. Eckhardt, "Selection of Raman laser materials," IEEE J. Quant. Electr. QE-2, 1, 1966. 

5. Commercial Q-switch dye available from Korad Division of Union Carbide, Santa Monica, California. 

6. J. A. Duardo and F. M. Johnson, " Evidence for quenching of stimulated Raman scattering of 5289 A laser radiation by two- 
photon absorption in organic liquids," /. Chem. Phys. 45, 2325, 1966, and Ref. 23. 

7. Ref. 1, Chapt. 7, pp. 243-246. 

8. G. Eckhardt, R. W. Hellwarth, F. J. McClung, S. E. Schwarz, and D. Weiner, " Stimulated Raman scattering from organic 
liquids," Phys. Rev. Lett., 9, 455^57, 1962. 

9. M. Geller, D. P. Bortfeld, and W. R. Sooy, " New Woodbury-Raman laser materials," Appl. Phys. Lett., 3, 36-40, 1963. 

10. S. Kern and B. Feldman, " Stimulated Raman emission," M.I.T. Lincoln Lab. Solid-State Res. Rept., 3, 18, 1964. 

11. D. P. Bortfeld, M. Geller, and G. Eckhardt, "Combination lines in the stimulated Raman spectrum of styrene," /. Chem. 
Phys, 40, 1770-1771, 1964. 

12. J. A. Calviello and Z. H. Heller, " Raman laser action in mixed liquids," Appl. Phys. Lett. 5, 1 12-113, 1964. 

13. R. W. Minck, R. W. Terhune, and W. G. Rado, "Laser-stimulated Raman effect and resonant four-photon interactions in 
gases H 2 , D 2 , and CH 4 ," Appl. Phys. Lett. 3, 181-184, 1963. 

14. V. A. Subov, M. M. Sushchinskii, and I. K. Shuvalton "Investigation of the excitation threshold of induced Raman scatter- 
ing" /. Exp. Theor. Phys. (USSR), 47, 784-786, August 1964. 

15. G. Eckhardt, "Selection of Raman laser materials," IEEE J. Quant. Electr. QE-2, 1-8, 1966. 

16. D. L. Weinberg, " Stimulated Raman emission in crystals and organic liquids," M.I.T. Lincoln Lab. Solid-State Res. Rept. 2, 
31, 1965. 

17. J. J. Barrett and M. C. Tobin, " Stimulated Raman emission frequencies in 21 organic liquids," /. Opt. Soc.Amer., 56, 129-130, 
1966. 

18. P. E. Tannenwald and J. B. Thaxter, " Stimulated Brillouin and Raman scattering in quartz at 2.1° to 293° Kelvin," Science, 
134, 1319-1320, 1966. 

19. M. D. Martin and E. L. Thomas, " Infrared difference frequency generation," IEEE J. Quant. Electr. QE-2, 1966. 

20. M. Rokni and S. Yatsiv, " Resonance Raman effect in free atoms of potassium," Phys. Lett., 24a, 277, 1967. 

21. S. K. Kurtz and J. A. Giordmaine, " Stimulated Raman scattering by polaritons," Phys. Rev. Lett., 22, 192, 1969. 

22. J. Gelbwachs, R. H. Pantell, H. E. PuthofT, and J. M. Yarborough, "A tunable stimulated Raman oscillator" Appl. Phys. 
Lett., 14, May 1, 1969. 

23. M. A. El-Sayed, F. M. Johnson and J. Duardo, "A comparative study of the coherent Raman processes using the ruby and 
the second harmonic neodymium giant-pulsed lasers," /. de Chimie Physique, No. 1, 227, 1967. 

24. J. A. Duardo, L. J. Nugent and F. M. Johnson, " Combination lines in stimulated Raman emission from gas mixtures," 
/. Chem. Phys. 46, 3585, 1967. 

25. H. H. Landolt and R. Bornstein, Zahlenwerte and Funktionen. Berlin, Germany: Springer- Verlag, 1951, 1. Band, 2 und 3 Teil. 

26. Geoscience Instruments Company, Mt. Vernon, New York. 

27. F. M. Johnson, J. A. Duardo and G. L. Clark, " Complex stimulated Raman vibrational-rotational spectra in hydrogen," 
Appl. Phys. Lett. 10, 157, 1967. 

28. J. A. Duardo, F. M. Johnson and L. J. Nugent, " Some new aspects in stimulated Raman scattering from hydrogen gas, 
IEEE J. Quant. Electr." QE4, No. 6, June 1968. 



Section 6 

Optical Pattern Storage 
Techniques and Materials 



Page 

533 Direct Optical Storage Media 

549 Holographic Parameters and Recording Materials 



Direct Optical Storage Media 

Juan J. Amodei 

RCA Laboratories 
Princeton, NJ. 08540 

INTRODUCTION 

This chapter presents a summary of data and discussion on media that are suitable for direct 
optical recording of images or holographic information. The materials that are included require no 
development of any sort after exposure and were chosen to be representative of what is presently avail- 
able for permanent or temporary storage of this type. The properties and features of the materials and 
the techniques required for recording vary widely among the examples that are covered, so that no 
standard set of parameters could be used to describe each candidate. Fairly detailed descriptions and 
explanations are therefore included, so as to make the subject reasonably easy to follow without undue 
reliance on published literature. 

The materials are grouped into two classes, depending on whether they modulate the phase or the 
amplitude of the readout light with the recorded information. The first are labeled "Phase Recording 
Media " and the second, " Amplitude Recording Media." 

PHASE RECORDING MEDIA 

The phase recording media that are discussed here operate through light-induced changes in the 
index of refraction, which occur through the magneto-optic and electro-optic effects. Media that operate 
on the phase of the light through thickness changes or other mechanisms usually require some sort of 
development process, and do not qualify as direct storage media. Organic materials that undergo 
photochemical reactions with consequent change in index of refraction are not sufficiently well develop- 
ed at this stage to be included here. 

MANGANESE BISMUTH FILMS 

Manganese bismuth is a ferromagnetic material characterized by large magneto-optical effects, a 
high anisotropy, a large magnetization, a large coercivity, a relatively low Curie temperature, and when 
in thin film form, a very small minimum domain size. Because of these characteristics, MnBi has been 
recognized as the most attractive medium for magneto-optic storage, a technique that has the significant 
advantage of being truly reversible while providing permanent memory. 

In early experiments the heat of a soldering iron, 1 and then of an electron beam, 2 was used to store 
patterns. With the advent of the laser, the heat generated by the absorption of an intense light beam has 
been used for Curie-point writing. 3 

Curie-point writing is achieved by heating a region of a thin, magnetically saturated film above its 
Curie temperature, causing that region to lose its magnetization (i.e. become paramagnetic). When the 
source of heat is removed the film will cool to a temperature below the Curie point and the region will 
again become ferromagnetic, but the direction of magnetization will be reversed due to the demagnetiz- 
ing fields of neighboring unheated areas of the film. 

The stored data can be read by either the Faraday or polar Kerr magneto-optic effects. The plane of 
polarization of incident, linearly polarized light is rotated in proportion to the direction and magnitude 
of the film's magnetization; the polarization of light passing through or reflected from Curie-point 
written spots will be different from that passing through unheated regions of the film. If circularly 

533 



534 Handbook of Lasers 

polarized light is incident on the film, then the different directions of magnetization give rise to different 
phase delays of light passing through the film. (It is noted that rotation of linearly polarized light is a 
special case of this, due to a difference in phase delay of its left- and right-handed, circularly polarized 
components.) 

Data, either in digital or in pictorial form, may be stored directly or holographically. In the direct 
form a spot, or image, is focused on the film and the film is exposed. Read-out is then accomplished by 
the use of linearly polarized light, with the different directions of magnetization distinguished with an 
analyzer. Holographic storage 5 is achieved by recording the fringe pattern caused by the interference of 
an object wave and reference wave at the film as a corresponding magnetization pattern. The change in 
phase of the light passing through the film (Faraday effect), which is in proportion to the local mag- 
netization, can be used for read-out; the magnetic hologram behaves as a phase hologram. In order to 
preserve the resolution and sensitivity, the writing must be accomplished in times that are shorter than 
50 nsec. This is to avoid losses through heat conduction and, in general, necessitates the use of pulsed 
lasers for holographic storage. 

Erasure of the stored magnetization pattern is accomplished by uniformly remagnetizing the film 
by means of an external magnetic field. 

MnBi films are fabricated by the sequential deposition of equal-thickness layers of bismuth and 
manganese on either crystalline (mica or sapphire) or amorphous (glass) substrates. The film is then 
heated in vacuum to about 300°C for periods of up to 72 hours. 

The pertinent parameters of MnBi and Curie-point storage are : 



Write energy 

Read efficiency:* direct 

holographic 
Faraday rotation 
Kerr rotation 
Absorption coefficient 
Coercive field 
Magnetization 
Minimum domain size 
Anisotropy constant 
Curie temperature 

ELECTRO-OPTIC RECORDING MEDIA 



10 " 2 joule/cm 2 

.3% 

.01-.05% 

>5 x 10 5 /cm 

«3° 

3.5 x 10 5 /cm 

700 Oe 

7.5 kgauss 

< 2000 A 

8.9 x 10 6 erg/cm 3 

360°C 



High-efficiency, volume phase holograms can be stored in certain electro-optic crystals, such as 
lithium niobate and lithium tantalate. 6 The process relies on the optical excitation and subsequent drift 
or diffusion of electrons, which originate from localized centers in the crystal. Regions of unneutralized 
charge thus generated give rise to field patterns resembling the intensity profile of the holographic 
interference pattern. The fields modulate the index of refraction of the material and the result is a 
phase hologram, whose efficiency could theoretically be as high as 100%. 

Holographic efficiencies as high as 60 % have been obtained in crystals that are about 1 cm thick. 
Proper storage procedure requires that the optic axis of the crystal be perpendicular to the fringe gratings 
of the hologram. High-efficiency readout can be accomplished only with light polarized in the plane 
containing the optic axis. 

The sensitivity of the materials is very low compared to other recording media and varies between 
30 and 100 joules/cm 2 (at X = 4880 A), depending on the treatment to which the material was subjected. 
Storage times of many days are possible at ordinary room illumination levels and erasure can be achieved 
either optically or by heating the crystal to 170°C. 

Application of an electric field has been shown to improve the performance of barium strontium 
niobate as an electro-optic recording material, 7 but the published diffraction efficiencies (2%) were 
considerably lower than in lithium niobate and lithium tantalate. 

* Percentage of light power in the image compared to incident power of readout light. 



20 Optical Storage Media 535 

AMPLITUDE RECORDING MEDIA 

The materials discussed here record through photo-induced changes in their absorption coefficient 
(photochromies) or through a change in their actual thickness through vaporization by high intensity 
light (thin films). 

INORGANIC PHOTOCHROMICS 

The phenomenon of color centers in transparent crystals is caused by the presence of impurities or 
imperfections, which give rise to localized states within the forbidden gap of the material. These states 
may either trap an electron, which in turn would show absorption at visible wavelengths where the pure 
crystal is transparent, or may cause absorption bands via the excitation of electrons from the valence 
band into these states. The photochromic phenomenon consists of the ability to (reversibly) switch 
colors (shapes of the absorption bands) under the influence of optical irradiation. In most inorganic 
crystals this change is caused by the transfer of an optically excited electron from one type of color 
center to another, with a consequent change in the absorption characteristics of the sample. Light of one 
wavelength produces a given change, while light of a different wavelength will return the crystal to its 
original state. 

The performance of inorganic photochromies as reversible optical storage media can be measured, 
in terms of the maximum absorption change induced by light, the energy required to produce a given 
change, the background absorption, and the storage time of the material. The inherent resolution of the 
materials themselves is practically unlimited and, in the storage of two-dimensional real images, it is 
limited by geometric considerations having to do with the thickness required to give the desired con- 
trast ratio. Resolutions of several thousand lines per millimeter are usually well within the capabilities 
of the materials when used for holographic storage applications. 

The sensitivity of the materials for bleaching or coloring is determined by the quantum efficiency of 
the process and varies widely from material to material. 

The maximum storage time of the crystals is usually determined by the thermal activation energy of 
the traps, and varies from months to minutes. 

Table 20-1 shows a summary of performance of a selected group of materials, which are represen- 
tative of the wide range of properties that can be obtained by using different centers and/or different host 
lattices. The following notes refer to the use of Table 20-1 : 

(a) All values are for use at room temperature ( ~ 300°K). In all cases, thermal decay can be slowed 
by going to lower temperature. 

(b) O.D. refers to Optical Density, defined as 

O.D. = log-, 

where 7" is the transmission (e.g., ratio of output to input intensity). 

(c) The energy for color or bleach is the approximate absorbed energy required to obtain a 0.3 
O.D. change (a contrast ratio of 2) at the wavelength of maximum visible absorption change. 

(d) Absorption curves are given for some of the materials in the bleached and colored states, as 
noted by the figure number in the reference column. 

ORGANIC PHOTOCHROMICS 

The phenomenon of photochromism has been observed in an extremely large number of organic 
materials. Many hundreds of compounds have been rather intensively studied, and among these may be 
found examples in which the absorption spectra of either or both metastable and stable forms lie in 
virtually any desired region of the near-ultraviolet to long-wavelength visible spectrum. A thorough 
treatment of this subject is covered in a recent review, 21 to which the reader is referred for details on the 
phenomena and materials to be discussed below. 

There shall be treated here a few representative examples of several classes of behavior shown by 
organic materials. These examples have been selected on a fairly arbitrary basis, the availability of 
published material being a deciding criterion. 



536 



Handbook of Lasers 



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WAVELENGTH (|im) 

Fig. 20-1. Absorption tw. wavelength for 
Corning Type 5 Photochromic Glass (Ref. 11). 




4 5 .6 .7 8 

WAVELENGTH (/im) 

Fig. 20-2. Absorption vs. wavelength for SrTi0 3 doped 
with 0.03% Fe and 0.03% Mo. 




WAVELENGTH (/in) 

Fig. 20-3. Absorption vs. wavelength for SrTi0 3 doped 
with 0.02% Ni and 0.15 %Mo. 



538 



Handbook of Lasers 



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WAVELENGTH (A) 

Fig. 20-4. Absorption vs. wavelength for CaF> doped 
with 0.08% Na and 0.08% La (Ref. 19). 



General Considerations 

In all cases, the photochromic phenomenon shown by organic materials may be described by the 
scheme : 



A + 



hv' and/or kT 



B 



This notation suggests that there is a thermodynamically most stable state of the system, A, which, 
upon irradiation with light of frequency v produces a metastable state B. B may be a structural isomer 
or tautomer of A, one or more ionic or radical fragments derived from A, or a relatively stable electronic 
or vibrationally excited state of A. B may be converted back to A by either or both of two processes : 
by irradiation with light frequency v' associated with the absorption spectrum of B, and/or by a thermal 
(activated) process in the dark. It is to be understood that, in some cases, one or more transient species 
may intervene between A and B, and that there may, therefore, be more than one pathway between the 
two states. The kinetics which describe the B -*■ A reaction may range from a simple first order behavior 
to fairly complex processes. 

Those considerations which determine the utility of a specific photochromic phenomenon for a 
particular application would include : 

1 . The wavelengths at which A and B absorb ; 

2. The separation of the absorption bands of A and B ; 

3. The molar extinction coeflicient(s) (e) of each form at the wavelength of irradiation; 

4. The quantum efficiency, O (the probability that one state is converted to the other upon absorp- 
tion of a photon of light), of both the A -> B and B -*• A photoreactions ; 

5. The rate with which the dark (thermal) return of B to A takes place in a given medium at a 
given temperature ; 

6. The " purity " of the photoreaction(s) : if irradiation of the photochromic material causes any 
side-reactions that do not produce A or B, and especially if these side-reactions are not reversible, 
then deterioration ("fatigue") of the photochromic element will be observed and this will limit 
the number of cycles through which the system may be switched before a significant amount of 
the photoactive material is destroyed. 

It is unfortunate that this last important property of organic photochromic materials is the one that is 
least understood and has been studied the least. In general the "fatigue" shown by a specific material 
will be strongly dependent on the host and other particular features of the environment in which it is 
studied. 

While accurate data, as called for under items 3-5 above, are necessary to give quantitative infor- 
mation about the performance of a given photochromic material, in many cases these data are un- 
available, especially for the B -»• A process. This is often the case because of a rapid thermal reversion 



20 Optical Storage Media 539 



of B to A or because B cannot be isolated in a pure state for study. In some cases, procedures have 
been developed permitting accurate measurements on the B state, and thus the B -> A process, without 
requiring its physical isolation. 22 

As a consequence, the descriptive material to be tabulated below is largely qualitative in nature. 

Photochromism by Cis-Trans Isomerization 

Important examples of compounds which show this behavior are the aromatic azo compounds 
such as azobenzene : 



CK-O: 



hv 



hi/ or kT 



trans 

(A) 

and many indigoid dyes related to thioindigo : 




hi/ 



hV or kT 



Ou 




N = N 



CIS 
(B) 




^l 



trans 
( A) 



CIS 
(B) 



Most of the simple substituted aromatic azo compounds are yellow to orange in color. The trans 
isomers are the more stable (A form) and absorb at somewhat longer wavelengths than the cis isomers. 
Often, the absorption bands of the two isomers show considerable overlap. Little has been reported on 
the fatigue of these compounds. 

The indigoids are among the most light-stable of commercial dyes. Again, the trans forms are the 
more stable, and absorb at longer wavelength, typically beyond 500 nm. Absorption maxima of cis 
and trans isomers can be well-separated. Fatigue shown by indigoid dyes appears to be quite sensitive 
to environment; in a host which excludes oxygen, many thousands of cycles can be brought about 
without any observable dye degradation. 

The thermal cis -> trans (B -> A) isomerizations of all materials showing this phenomenon can be 
acid-catalyzed and, in some cases studied, are solvent-dependent. 

There have been a few reports of the photochromic behavior of azo compounds 23 and indigoids 24 
in polymeric hosts. 

Photochromism by Heterolytic Cleavage 

In this process, a covalent chemical bond is reversibly broken by a photolytic process to give a pair 
of ions, one positively charged the other negatively charged. The most widely studied group of com- 
pounds that show this behavior consists of a large number of spiro compounds related to 1', 3', 3'-tri- 
methylspiro — [2H- 1 -benzopyran-2,2'-indoline] : 



CH, 



CH3 



CH, 



CH 3 



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hi/ 






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L *jf N 


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hi/ or kT 


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colorless 


m 




colored 


(A) 






( B) 



Here, both charges remain in the same, zwitterionic, molecule. 

In general, the colorless forms of these compounds show one or more peaks in the 300-375 nm 
region of the ultraviolet with e of the order of 10 4 , and one or more peaks in the 220-275 nm region 



540 



Handbook of Lasers 



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20 Optical Storage Media 541 

absorbing 2-5 times more intensely. They are soluble in a wide range of solvents, and also in polymers. 25 
The colored forms have a type of merocyanine dye structure and show strong absorption, which may 
lie anywhere between ca. 440 and 680 nm, more typically between 520-640 nm. The position of the 
absorption maximum of the colored forms is quite solvent-dependent. The extinction coefficients are 
ca. 3-4 x 10 4 in polar solvents and somewhat higher, ca. 3.6-6 x 10 4 , in non-polar solvents. 

In a number of these compounds, a thermal equilibrium exists between colored and colorless 
forms and its position is influenced by solvent and temperature. The kinetics of the thermal decolori- 
zation (B -> A) can be quite complex. Several colored and/or colorless intermediates have been pro- 
posed, their number and nature also being solvent-dependent. The half-lives of the colored forms at 
20°C can range from ca. 5 sec. to ca. 35 hours. The energies of activation for this process are 14-30 
kcal/mol. Electron-withdrav/ing substituents on the indole benzene ring (positions 4'-7') increase the 
rate of decolorization, as does decreasing the polarity of the solvent, while such substituents on the 
phenolic ring (positions 5-8) slow the rate. The quantum yields for coloration (Oa-b) range from as 
low as 1 % to virtually quantitative, being strongly influenced by solvent, structure, substituent, and 
temperature. A number of these materials show no photochemical decolorization, but, for those for 
which this behavior has been observed and measured, $ b -a varies from 0.5% to as high as 20%. 

The utility of the spiro compounds is somewhat limited by their tendency to fatigue — typically 
after some 500-1000 cycles. Techniques have been devised for "fixing" the colored images produced 
using these materials. 26 The examples listed in Table 20-2 were chosen arbitrarily and cannot even 
begin to represent this enormous, diverse group of photochromic compounds. 

Another group of compounds of some interest are the so-called leuco derivatives of the triaryl- 
methane dyes : 

Ar 3 C-X 3==± Ar 3 C e +X e 

kT 

leuco compound dye 

(A) (B) 

The "Ar " represents an aromatic function, usually phenyl or naphthyl. One or more of these will bear 
a/?-amino or substituted amino group. X may be OH, CN, bisulfite, or one of a number of other groups 
which can form stable anions. 

The leuco compounds are colorless, having absorption at 250-275 nm, e = 3.5-6 x 10 4 and, where 
all Ar's are phenyl, at 295-310 nm, e = 5-10 x 10 3 , or at 340-50 nm if one or more Ar is naphthyl. 
On irradiation, the C-X bond is broken. The Ar 3 C e species are actually members of a well-known class 
of ionic dyes, which includes Crystal Violet, Malachite Green, Methyl Violet, etc. These dyes absorb 
(in water) from ca. 540-640 nm. The extinction coefficients are ca. 5-10 x 10 4 , but vary considerably 
with concentration (may not obey Beer's Law above ~10 -5 molar) and pH. The B -> A reaction is 
purely thermal, no photochemical " erasure " having been observed. The kinetics of the B -*• A reaction 
are second order, depending on the concentration of both Ar 3 C e and X e as well as solvent and pH. 
Usually these compounds are employed in the presence of excess X e . The half-lives of the colored forms 
range from seconds to a few minutes. Energies of activation for the fade reaction are ca. 14-16 kcal/mol. 
Only a few compounds have had accurate values of O measured. In some media (coated on paper bases, 
in polymers) or when Ar is naphthyl, the substances may require heating in order to be photocolored. 
Self-filtering of the activating light by buildup of absorption due to the colored form complicates the 
coloring process. The colored forms are often quite fugitive, and fatigue or simple photo-fading of the 
colored form is a serious limitation to repeated use. Image fixing techniques (formation of insoluble 
salts of Ar 3 C e , or removal of X e ) have been devised. 27,28 

Photochromism by Homolytic Cleavage 

This process is similar to the one above, except that the cleavage produces a pair of radicals. 
Because of the high chemical reactivity of such species, the majority of proceses of this type have only 
been observed at low temperatures in rigid media (frozen solvents). 



542 



Handbook of Lasers 



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20 Optical Storage Media 543 

An example of this phenomenon, which occurs at room temperature and which has been sufficiently 
well-described to include here, is bis-2,4,5-triphenylimidazol : 

9"^ d> 4> <P 

dimer colored radical 

(A) CB) 

The dimeric form has, in benzene solution, A max = 280 nm, e = 28,500. Upon irradiation, a reddish 
purple color (due to the radical, B) is formed. The colored state shows an ESR signal and has absorption 
maxima and e of 347 (1100), 520 (shoulder), and 554 nm (190). In the presence of oxygen the colored 
form is destroyed. Thermal fading takes place in the dark by a second-order process with an energy of 
activation of 7.3 kcal/mol. This process has also been observed to take place on irradiating the solid 
bis-imidazole. Reflection spectra of the colored state show maxima at 554 and 562 nm. Fading of the 
colored solid shows complex kinetics. 

A similar, but possibly unrelated behavior is shown by 3(N)-3-pyridyl sydnone: 

o- N 



•-U-O 



This compound has X max 238 and 325 nm, e = 4677 and 1413 in cyclohexane solution. It is not 
photochromic in solution, but, in the solid state, irradiation in the absence of oxygen with X as long as 
430 nm produces a deep blue color (A-600nm) which fades "overnight" at room temperature, 
"rapidly" at 80°. No ESR signal is associated with the blue color, but introduction of oxygen fades it 
to a yellow color which does have an ESR signal. The blue color is believed to arise via the formation 
of " color centers " in the solid compound. 

Photochromism by Tautomeric Processes 

For the purposes of the present discussion, tautomerism is taken to mean the transfer of an atom, 
in most of these cases a hydrogen atom, from one portion of a molecule to another under the influence 
of light absorption. The new species thus formed shows a change in its spectrum, usually as a result 
of the redistribution of electrons to form a more highly conjugated system. In some of the examples 
to be given, the primary hydrogen transfer may be followed by loss of a proton to produce a colored 
anion. While a number of materials which show phototautomerism have been reported, a majority of 
them seem unattractive as a basis for practical photochromic systems, since they tend to be oxygen- 
sensitive, have very rapid thermal return rates except at low temperatures, and/or show pronounced 
fatigue after a few cycles. 

OXYGEN-TO-NITROGEN HYDROGEN TRANSFER (OH -+ N). 



Q- 



Salicylideneaniline 
H 
Q _ K?/ i Vc. 



H 



pale yellow r ed 



(A) 



(B) 



While some compounds of this type show solution photochromism at liquid nitrogen temperatures, 
this compound shows interesting behavior in the form of thin films of the pure solid. Two crystalline 
modifications, designated a t and a 2 have been studied and are described in Table 20-4 



544 Handbook of Lasers 

CARBON TO NITRO-OXYGEN TRANSFER (CH->0 2 N) 

4-(2,4-dinitrobenzyl) pyridine 

O-N HO— N 

O •- o 



H-N^»CH-A-Ni 



NO z 

colored form (B) 

Here, after the photo-induced hydrogen transfer, a second transfer, to the pyridine nitrogen, occurs 
which tends to stabilize the tautomeric form (increases lifetime of colored state), as compared with 
other o-nitrobenzyl systems which do not have this means of stabilization available. Again, this material 
shows its most interesting behavior at room temperature in the solid state. Quantum yields tend to be 
low, and fatigue is observed on repeated cycling. 

CARBON TO CARBOXYLATE TRANSFER (CH -> Q OCO) 

2-(4-nitrobenzyl)benzoate 



cod" c ° 

V _ f 

:H= 0= N f 




+ H ' 

O 
COO 

colored form 

These materials represent one of the few photochromic systems that operate in aqueous solution. 
The initial proton shift is followed by ionization to give the colored form. The quantum yields are 
reasonably high (10-30%). High optical densities can be achieved, and the half-lives of the colored 
forms can be controlled by the pH of the medium, in that the rate constants for decolorization are pro- 
portional to the hydrogen ion concentration of the solution. Again, the colored form is stabilized by 
ionization of the hydrogen atom. These systems do, however, also suffer from oxygen sensitivity and 
poor reversibility. 

NITROGEN-TO-NITROGEN HYDROGEN TRANSFER (NH->N) 

A number of metal chelates of diphenylthiocarbazone (dithizone) : 

S 
II 
<j>— N=N— CNHNH0, 

which presumably contain the ring structure: 

M 

H—tsT 



20 Optical Storage Media 545 

are yellow to red colored compounds, which on irradiation in their visible absorption bands show a 
change in color from red to violet. This process is believed to take place by a combination of hydrogen 
transfer and trans-to-cis isomerization, resulting in an alteration of the ring structure. The compounds 
show reasonably good light stability (if UV irradiation is avoided) and the phenomenon is observed in 
plastic films. 29 Photochromic sunglasses have been marketed using films containing such materials 
(probably the mercury derivative, the metastable state of which has the longest half-life). 

OTHER. One other type of tautomerization that has been extensively studied is illustrated by the 
bianthrones. 




CH3 



CH 3 



CH 



1, 3, 6', 8'-Tetramethylbianthrone "Dihydrophenanthrone" 

Stable Form (A) Metastable Form (B) 

While the structure of the B form of this system is still the subject of controversy, it is likely that 
it is the compound that results from formation of a new carbon-carbon bond between the two anthrone 
rings.Some compounds of this type, without methyl groups in the l,8'-positions,are also thermochromic, 
show only low-temperature photochromism, and are more subject to irreversible photoreactions and the 
adverse effects of oxygen. The above compound has been studied in a polymethylmethacrylate host. 30 

Photochromism by Triplet-State Formation 

Windsor and co-workers 31,32 have reported on a novel procedure for reversibly forming colored 
species by exciting a number of polycyclic aromatic hydrocarbons with ultraviolet light in rigid matrices 
(polymers such as polymethylmethacrylate [PMM] and epoxy resins). Upon excitation to the first 
excited singlet state, these molecules undergo efficient intersystem crossing to their triplet states (the 
metastable form, B). In these rigid hosts, the lifetimes of the triplet states can be as long as tens of 
seconds. The triplet states are molecular entities and have strong absorption in the visible portion of 
the spectrum. The plastic samples containing the aromatic compounds must be protected from the slow 
inward diffusion of oxygen, whose reaction with the triplet states irreversibly destroys the active ma- 
terials. Samples were still active after 3 weeks of exposure to sunlight, but the maximum absorbance is 
reduced by ca. 2.5% with each activating flash, possibly as a result of reaction of the excited molecules 
with a component of the host polymer. 32 

EVAPORATED THIN FILMS 

Optical vaporization of thin deposited layers of absorptive or reflective materials has been shown 
to be a simple and highly successful technique of permanently recording information. 33 The process 
consists of depositing a thin uniform layer of material on a glass or other suitable substrate and record- 
ing the information by selectively vaporizing portions of the layer with the high power obtained from a 
focused CW laser of a Q-switched pulsed laser. The materials can be used for real-image or holographic 
recording, the only requirement being that the power density of the writing beam be sufficient to supply 
the energy needed for recording in times that are short compared to the thermal time constants. Any 
absorptive or reflective medium that lends itself to good thin coatings is suitable for this application, 
but the most sensitive materials are those with low thermal conductivity and low boiling point. Two 
materials that are well suited for this application are bismuth and tellurium. The film thickness should 
be between about 70 and 2000 A, so as to have sufficient thickness to record on, but not increase the 
lateral conductivity exceedingly. The incident energy required to record on these materials, when using 
Q-switched pulsed ruby laser pulses of about 20 /xsec duration, is of the order of 50 x 10" 3 J/cm 2 . 
Holographic efficiencies of 6 % can be obtained with these materials and resolution of over 1000 lines/mm 
is possible. 33 



546 



Handbook of Lasers 



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6. F. S. Chen, T. T. LaMacchia, and D. B. Fraser, "Holographic storage in lithium niobate," Appl. Phys. Lett., 13, 223, 1968. 

7. J. B. Thaxter, "Electrical control of holographic storage in strontium-barium niobate," Appl. Phys. Lett., 15, 210, 1969. 

8. S. Eros, Final Report, Department of the Army Contract No. Da 49-092-ARO-59, 1965. 

9. A. N. Carson, Technical Report AFAL-TR-66-61 for Air Force Contract No. AF 33(61 5)-2911, 1966. 

10. B. W. Faughnan, D. L. Staebler, and Z. J. Kiss, "Appl. Solid State Science," Vol. 2, Academic Press, New York, 1970. 

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12. G. P. Smith, IEEE Spectrum, 3, 39, 1966. 

13. B. W. Faughnan and Z. J. Kiss, Phys. Rev. Lett., 21, 1331, 1968. 

14. B. W. Faughnan and Z. J. Kiss, IEEE J. Quant. Electr. QE-5, 17, 1969. 

15. B. W. Faughnan, Personal Communication. 

16. R. C. Duncan, B. W. Faughnan, and W. Phillips, Appl. Optics, p 2236, October 1970. 

17. D. L. Staebler and Z. J. Kiss, Appl. Phys. Lett., 14, 93, 1969. 

18. D. L. Staebler and R. C. Duncan, to be published. 

19. W. Phillips and R. C. Duncan, to be published in the Trans. Met. Soc. 

20. E. F. Williams, W. G. Hodgron and J. S. Brinen,/. Am. Ceram. Soc. 52, 139, 1960. 

21. "Photochromism," G. H. Brown, ed., Wiley-Inter