Springer Series in Optical Sciences Volume 1

Springer Series in Optical Sciences Editorial Board: A. L. Schawlow K. Shimoda A. E. Siegman T. Tamir

Managing Editor: H. K. V. Lotsch

42 Principles of Phase Conjugation 57 Single-Mode Fibers Fundamentals By B. Ya. Zel'dovich, N. F. Pilipetsky, By E.-G. Neumann and V. V. Shkunov

43 X-Ray Microscopy 58 Photoacoustic and Photothermal Phenomena

Editors: G. Schmahl and D. Rudolph Editors: P. Hess and J. Pelzl

44 Introduction to Laser Physics 59 Photorefractive Crystals By K. Shimada 2nd Edition in Coherent Optical Systems

45 Scanning Electron Microscopy ByM. P. Petrov, S. I. Stepanov,

Physics oflmage Formation and Microanalysis andA.V. Khomenko

ByL.Reimer 60 Holographic Interferometry

46 Holography and Deformation Analysis in Experimental Mechanics ByW. Schumann, J.-P. Ziircher, and D. Cuche By Yu. I. Ostrovsky, V. P. Shchepinov,

47 Tunable Solid State Lasers and V. V. Yakovlev Editors: P. Hammerling, A. B. Budgor,

61 MiUimetre and SubmiUimetre Wavelength Lasers andA.Pinto

48 Integrated Optics A Handbook of cw Measurements

Editors: H. P. Nolting and R. Ulrich ByN. G. Douglas

49 Laser Spectroscopy VII 62 Photoacoustic and Photothermal Phenomena II Editors:T. W. HanschandY. R. Shen Editors: J. C. Murphy, J. W. Maclachlan Spicer,

50 Laser-Induced Dynamic Gratings L. C. Aamodt, and B.S. H. Royce

By H. J. Eichler, P. Giinter, and D. W. Pohl 63 Electron Energy Loss Spectrometers 51 Tunable Solid State Lasers for Remote Sensing The Technology of High Performance

Editors: R. L. Byer, E. K. Gustafson, By H. Ibach and R. Trebino

52 Tunable Solid·State Lasers II 64 Handbook of Nonlinear Optical Crystals

Editors: A. B. Budgor, L. Esterowitz, ByV. G. Dmitriev, G. G. Gurzadyan,

and L. G. DeShazer and D. N. Nikogosyan

53 The C02 Laser ByW.J. Witteman 65 High-Power Dye Lasers 54 Lasers, Spectroscopy and New Ideas Editor: F. J. Duarte

A "Tribute to Arthur L. Schawlow Editors: W. M. Yen and M. D. Levenson 66 Silver Halide Recording Materials for Holography

55 Laser Spectroscopy VIII and Their Processing

Editors: W. Persson and S. Svanberg By H. I. Bjelkhagen

56 X· Ray Microscopy II 67 X-Ray Microscopy Ill Editors: D. Sayre, M. Howells,J. Kirz, and Editors: A. G. Michette, G. R. Morrison, H.Rarback and C. J. Buckley

Volumes 1-41 are listed at the end of the book

Walter Koechner

Solid-State Laser Engineering Third Completely Revised and Updated Edition

With 414 Figures

Springer-Verlag Berlin Heidelberg GmbH

Dr. WALTER KoECHNER

Fibertek, Inc., 510 Herndon Parkway Herndon, VA 22070, USA

Editorial Board

ARTHUR L. SCHAWLOW, Ph. D.

Department of Physics, Stanford University Stanford, CA 94305, USA

Professor KmcHI SHIMODA, Ph. D.

Faculty of Science and Technology Keio University, 3-14-1 Hiyoshi, Kohoku-ku Yokohama 223, Japan

Professor ANTHONY E. SIEGMAN, Ph. D.

Electrical Engineering E. L. Ginzton Laboratory, Stanford University Stanford, CA 94305, USA

THEODOR TAMIR, Ph. D.

Polytechnic University 333 Jay Street, Brooklyn, NY 11201, USA

Managing Editor: Dr. HELMUT K. V. LoTSCH

SI?ringer-Verlag, Tiergartenstrasse 17, W-6900 Heidelberg, Fed. Rep. of Germany

ISBN 978-3-662-14515-9

Library of Congress Cataloging-in-Publication data. Koechner, Walter, 1937- Solid-state laser engineering I Walter Koechner.-3rd completely rev. and updated ed. p. cm.-(Springer series in optical sciences; v. 1) Includes bibliographical references and index. ISBN 978-3-662-14515-9 ISBN 978-3-662-14513-5 (eBook) DOI 10.1007/978-3-662-14513-5 1. Solid-state lasers. I. Title. II. Series. TA1705.K63 1991 621.36'61-dc20 91-29337

This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag Berlin Heidelberg GmbH. Violations are liable for prosecution under the German Copyright Law.

© Springer-Verlag Berlin Heidelberg 1976, 1988, 1992 Originally published by Springer-Verlag Berlin Heidelberg New York in 1992 Softcover reprint of the hardcover 3rd edition 1992

The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective Jaws and regulations and therefore free for general use.

Typesetting: SpringerTEX in-house system 54/3140-543210- Printed on acid-free paper

Preface to the Third Edition

This book, written from an industrial vantage point, provides a detailed discussion of solid-state lasers, their characteristics, design and construction, and practical problems. The title Solid-State Laser Engineering is chosen so as to convey the emphasis which is placed on engineering and practical considerations.

The author has tried to enhance the description of the engineering aspects of laser construction and operation by including numerical and technical data, tables, and curves.

The book is mainly intended for the practicing scientist or engineer who is interested in the design or use of solid-state lasers, but it is hoped that the com­prehensive treatment of the subject makes the work useful also to students of laser physics who want to supplement their theoretical knowledge with the engi­neering aspects of lasers. Although not written in the form of a college textbook, the book might be used in an advanced college course on laser technology.

The aim was to present the subject as clearly as possible. Phenomenological descriptions using models were preferred to an abstract mathematical presenta­tion, even though many simplifications had then to be accepted. Results are given in most cases without proof since the author tried to stress the application of the results rather than the derivation of the formulas. An extensive list of references is cited for each chapter to permit the interested reader to learn more about a particular subject.

Gratified by the wide acceptance of the previous editions of Solid-State Laser Engineering, I have updated and revised the second edition to include develop­ments and concepts which have emerged during the last several years. Some aspects of the field have reached a high level of maturity such as the opti­cal, mechanical, and electronic design of flashlamp-pumped solid-state lasers, Q-switching, and mode locking. Other technologies are just evolving or are in a process of rapid development such as diode-pumped lasers, tunable lasers, single frequency operation, unstable resonators employing variable reflectivity mirrors, phase conjugation and frequency conversion employing new nonlinear materials.

It is impossible to describe all the new materials, laser configurations, and pumping schemes which have been developed over the last several years. In doing so, the book would merely become a literature survey with commentaries. Readers interested in specific devices are referred to the original literature. Very good sources of information are the IEEE Journal of Quantum Electronics, Op­tics Letters, and the conference proceedings of the CLEO and Solid-State Laser Conferences.

v

The following areas have been expanded or treated in more detail compared to the previous editions:

Diode-array pumping: Significant progress has been made in recent years in the development of laser diode arrays which have become the building blocks for solid-state laser pumps. The two primary benefits derived from diode-laser pump­ing of solid-state lasers are improved efficiency and extended lifetime. Output power, slope efficiency, laser threshold and wavelength control of laser diodes have all been dramatically improved due to a combination of new structures and advanced growth techniques. Output power and power density of laser diode ar­rays have increased to the point where solid-state lasers with average powers in the kilowatt range can be built The arrays available today, and the laser perfor­mance which has been achieved, have clearly demonstrated that diode pumping is no longer a question of technical feasibility, but rather a question of economic viability. The high cost of diode arrays is the major obstacle which prevents broader acceptance of diode-pumped solid-state lasers at the present time.

Wavelength diversity: Significant progress has been made in the development of tunable lasers, in particular the Ti: sapphire laser, which is firmly established as the major tunable source in the near infrared. In addition, the performance of harmonic generators and optical parametric oscillators (OPOs) has been dra­matically improved as a result of new nonlinear materials. Generation of tunable radiation in the UV, visible and IR region of the spectrum is of great interest in many applications. The optical parametric oscillator has long been regarded as a convenient means of achieving tunable output from solid-state lasers. However, progress in the development of OPOs has been slow owing to a lack of suitable nonlinear materials and pump sources of desirable beam quality. The advent of new nonlinear materials such as KTP, BBO and WB in combination with the high beam quality obtained from diode-pumped lasers has revived interest in OPOs for the generation of tunable laser radiation.

Improved beam quality: Efficient heat removal and reduction of the thermal effects which are caused by the temperature gradients across the active area of the laser medium usually dominate design considerations for high average power systems. One of the advantages of diode laser pumping is that the waste heat dissipated in the laser rod is greatly reduced by the high efficiency of the pumping process. The reduction of thermal effects permits the design of resonators which maximize the mode volume at lower order modes. For example, the use of unstable resonators in conjunction with variable reflectivity mirrors has considerably increased the power extraction at low order modes compared to conventional resonators.

Single-frequency operation: Excellent frequency stability and single axial mode operation of diode-pumped unidirectional ring lasers make it possible to design coherent Doppler systems in the near-infrared wavelength regime.

Improved system efficiency: Overall system efficiency is one of the major attributes of diode pumping and great emphasis is placed on optimization of the various factors contributing to the overall performance. Therefore, the treatment of energy flow within a laser system as well as extraction efficiency of Q-switched

VI

and non-Q-switched lasers has been considerably refined compared to previous editions.

This book would not have been possible without the many contributions to the field of laser engineering that have appeared in the open literature and which have been used here as the basic source material. I apologize to any of my colleagues whose work has not been acknowledged or adequately represented in this book.

My special thanks are due to my son, Dirk, for proofreading the typeset pages, and to the editor, Dr. H. Lotsch, for his support in preparing the new edition for printing.

None of the editions of this book could have been written without the en­couragement, patience and support of my wife Renate.

Herndon, VA January 1992

Walter Koechner

VII

Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Optical Amplification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Interaction of Radiation with Matter . . . . . . . . . . . . . . . . . . . . . 2

1.2.1 Blackbody Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2.2 Boltzmann Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2.3 Einstein Coefficients . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2.4 Phase Coherence of Stimulated Emission . . . . . . . . . . 7

1.3 Absorption and Optical Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.1 Atomic Lineshapes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.2 Absorption by Stimulated Transitions . . . . . . . . . . . . . 13 1.3.3 Population Inversion . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.4 Creation of a Population Inversion . . . . . . . . . . . . . . . . . . . . . . 17 1.4.1 The Three-Level System . . . . . . . . . . . . . . . . . . . . . . . 18 1.4.2 The Four-Level System . . . . . . . . . . . . . . . . . . . . . . . . 19 1.4.3 The Metastable Level . . . . . . . . . . . . . . . . . . . . . . . . . . 20

1.5 Laser Rate Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2. Properties of Solid-State Laser Materials . . . . . . . . . . . . . . . . . . . 28 2.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.1.1 Host Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.1.2 Active Ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2.2 Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 2.3 Nd : Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

2.3.1 Nd: YAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 2.3.2 Nd : Glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 2.3.3 Nd : Cr : GSGG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 2.3.4 Nd : YLF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

2.4 Er : Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 2.4.1 Er: YAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 2.4.2 Er : Glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

2.5 Tunable Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 2.5.1 Alexandrite Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 2.5.2 Ti : Sapphire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

IX

3. Laser Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 3.1 Operation at Threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 3.2 Gain Saturation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 3.3 Circulating Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 3.4 Oscillator Performance Model . . . . . . . . . . . . . . . . . . . . . . . . . . 88

3.4.1 Energy-Transfer Mechanisms . . . . . . . . . . . . . . . . . . . . 89 3.4.2 Laser Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

3.5 Relaxation Oscillations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 3.5.1 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . · 103 3.5.2 Spike Suppression in Solid-State Lasers . . . . . . . . . . . 107 3.5.3 Gain Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

3.6 Examples of Regenerative Oscillators . . . . . . . . . . . . . . . . . . . 109 3.6.1 Ruby . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 3.6.2 Nd: Glass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 3.6.3 Nd : YAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 3.6.4 Alexandrite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 3.6.5 Laser-Diode-Pumped Systems . . . . . . . . . . . . . . . . . . . 127

3.7 Travelling-Wave Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

4. Laser Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 4.1 Pulse Amplification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

4.1.1 Ruby Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 4.1.2 Nd : Glass Amplifiers . . . . . . . . . . . . . . . . . . . . . . . . . . 157 4.1.3 Nd: YAG Amplifiers . . . . . . .. . . . . . . . . . . . . . . . . . . 162

4.2 Steady-State Amplification . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 4.2.1 Ruby Amplifier .. . .. . .. . .. . .. . . . . .. . . . . . . . . . . . 172 4.2.2 Nd : Glass Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . 173

4.3 Signal Distortion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 4.3.1 Spatial Distortions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 4.3.2 Temporal Distortions . . . . . . . . . . . . . . . . . . . . . . . . . . 180

4.4 Gain Limitation and Amplifier Stability . . . . . . . . . . . . . . . . . . 181 4.4.1 Amplified Spontaneous Emission . . . . . . . . . . . . . . . . 182 4.4.2 Prelasing and Parasitic Modes . . . . . . . . . . . . . . . . . . . 186

5. Optical Resonator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

X

5.1 Transverse Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 5.1.1 Intensity Distribution of Transverse Modes . . . . . . . . 189 5.1.2 Characteristics of a Gaussian Beam . . . . . . . . . . . . . . 192 5.1.3 Resonator Configurations . . . . . . . . . . . . . . . . . . . . . . . 195 5.1.4 Stability of Laser Resonators . . . . . . . . . . . . . . . . . . . . 200 5.1.5 Diffraction Losses . .. . . . . . .. . . . . . .. . . . . .. . . . . . . 201 5.1.6 Higher-order Modes .. .. . .. . .. . . .. . . .. . . . . . . . . . 202 5.1.7 Active Resonator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 5.1.8 Resonator Sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . . 206

5.1.9 Mode-selecting Techniques . . . . . . . . . . . . . . . . . . . . . 209 5.1.10 Examples of Advanced Stable Resonator Designs . . . 217

5.2 Longitudinal Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 5.2.1 Fabry-Perot Resonators . . . . . . . . . . . . . . . . . . . . . . . . 225 5.2.2 Spectral Characteristics of the Laser Output . . . . . . . . 232 5.2.3 Axial Mode Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

5.3 Temporal and Spectral Stability . . . . . . . . . . . . . . . . . . . . . . . . 249 5.3.1 Amplitude Fluctuations . . . . . . . . . . . . . . . . . . . . . . . . 249 5.3.2 Frequency Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252

5.4 Hardware Design ....................... ·. . . . . . . . . . . . . 254 5.5 Unstable Resonators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

5.5.1 Confocal Positive-Branch Unstable Resonator . . . . . . 261 5.5.2 Negative-Branch Unstable Resonators . . . . . . . . . . . . . 264 5.5.3 Variable Reflectivity Output Couplers . . . . . . . . . . . . . 266 5.5.4 Gain, Mode Size and Alignment Sensitivity . . . . . . . . 270

5.6 Wavelength Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

6. Optical Pump Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275 6.1 Pump Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275

6.1.1 Noble Gas Flashlamps . . . . . . . . . . . . . . . . . . . . . . . . . 279 6.1.2 Continuous Arc Lamps . . . . . . . . . . . . . . . . . . . . . . . . . 293 6.1.3 Tungsten-Filament Lamps . . . . . . . . . . . . . . . . . . . . . . 300 6.1.4 Laser Diodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302 6.1.5 Nonelectric Pump Sources . . . . . . . . . . . . . . . . . . . . . . 317

6.2 Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318 6.2.1 Operation of cw Pump Sources . . . . . . . . . . . . . . . . . . 318 6.2.2 Operation of Flashlamps . . . . . . . . . . . . . . . . . . . . . . . 320

6.3 Pump Cavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337 6.3.1 Pump Cavity Configurations . . . . . . . . . . . . . . . . . . . . 337 6.3.2 Energy Transfer Characteristics . . . . . . . . . . . . . . . . . . 352 6.3.3 Mechanical Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367

7. Heat Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381 7.1 Thermal Phenomena in Laser Rods . . . . . . . . . . . . . . . . . . . . . 381

7.1.1 cw Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382 7.1.2 Single-Shot Operation . . . . . . . . . . . . . . . . . . . . . . . . . 401 7.1.3 Repetitively Pulsed Lasers . . . . . . . . . . . . . . . . . . . . . . 404

7.2 Cooling Techniques . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 414 7.2.1 Liquid Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414 7 .2.2 Air or Gas Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418 7.2.3 Conductive Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . 419

7.3 Noncylindrical Laser Elements . . . . . . . . . . . . . . . . . . . . . . . . . 421

XI

8. Q-Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435 8.1 Q-Switch Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435 8.2 Mechanical Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 445 8.3 Electrooptical Q-Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 448 · 8.4 Acoustooptic Q-Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 466 8.5 Dye Q-Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471 8.6 Cavity Dumping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476

9. Mode Locking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 482 9.1 Passive Mode Locking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 486

9.1.1 Design and Perfonnance Characteristics of Passively Mode-Locked Solid-State Lasers . . . . . . 491

9.2 Active Mode Locking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 497 9.2.1 Design of Actively Mode-Locked Laser Systems . . . . 501

9.3 Active-Passive Mode Locking . . . . . . . . . . . . . . . . . . . . . . . . . . 507

10. Nonlinear Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508 10.1 Harmonic Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510

10.1.1 Basic Equations of Second-Harmonic Generation . . . 510 10.1.2 Parameters Affecting the Doubling Efficiency . . . . . . 518 10.1.3 Properties of Nonlinear Crystals . . . . . . . . . . . . . . . . . 525 10.1.4 Intracavity Frequency Doubling . . . . . . . . . . . . . . . . . . 531 10.1.5 Third-Harmonic Generation . . . . . . . . . . . . . . . . . . . . . 539 10.1.6 Examples of Harmonic Generation . . . . . . . . . . . . . . . 540

10.2 Parametric Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 545 10.2.1 Design Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 547 10.2.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 550 10.2.3 Design and Perfonnance

of Modern Optical Parametric Oscillators . . . . . . . . . . 553 10.3 Raman Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556 10.4 Optical Phase Conjugation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565

11. Damage of Optical Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570

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11.1 Surface Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571 11.2 Inclusion Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572 11.3 Self-focusing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 573 11.4 Damage Threshold of Optical Materials . . . . . . . . . . . . . . . . . . 579

11.4.1 Scaling Laws . . . .. . . . . . . . . .. . .. . . . . . .. . . . . .. . . 580 11.4.2 Laser Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 582 11.4.3 Damage in Optical Glass . .. .. .. .. . . .. .. . .. . . . . . 582 11.4.4 Damage Levels for Nonlinear Materials . . . . . . . . . . . 584 11.4.5 Laser Induced Damage in Dielectric Thin Films . . . . 585

11.5 System Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . 586

Appendix A

Appendix B

References

590

595

597

Subject Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 629

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