Topics in Applied Physics Volume 1 Founded by Helmut K. V. Lotsch
Dye Lasers Edited by F. P. Schafer With Contributions by K. H. Drexhage T. W. Hansch E. P. lppen F. P. Schafer C. V. Shank B. B. Snavely With 114 Figures Springer-Verlag Berlin Heidelberg GmbH 1973
Professor Dr. FRITZ PETER ScHAFER. Max-Planck-Institut fiir Biophysikalische Chemie, D-3400 Gottingen ISBN 978-3-662-11581-7 ISBN 978-3-662-11579-4 (ebook) DOl 10.1007/978-3-662-11579-4 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar meaps, and storage in data banks. Under 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to the publisher, the amount of the fee to be determined by agreement with the publisher. by Springer-Verlag Berlin Heidelberg 1973 Originally published by Springer-Verlag Berlin-Heidelberg-New York in 1973 Softcover reprint of the hardcover 1st edition 1973 Library of Congress Catalog Card Number 73-11593. The use of 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 laws and regulations and therefore free for general use. Typesetting, printing and bookbinding: Briihlsche Universitiitsdruckerei, GieBen.
Introduction to the Series <<fopics in Applied Physics» Recent progress in pure and applied research has produced vast quantities of results. The great need that this creates for authoritative reviews cannot be met by the scientific journals. Textbooks are, by their very nature, unsuitable for the discussion of specific topics in depth, and as a consequence the methods and results of newer research tend to receive rather cursory treatment. Advanced monographs usually appeal exclusively to experts in a particular field, and individuals find it expensive to purchase symposium proceedings or a collection of review papers for the sake of a particular article when the rest of the volume is of marginal interest. «Topics in Applied Physics» is a new series, published by Springer Verlag and devoted to critical reviews of subjects of current interest.in applied physics. This "monograph" series is intended to fill the gap described above. Each volume deals with a particular topic, and contributions are invited by an editor who is a recognized authority in the field in question. The authors are scientists who are actively engaged in advancing the frontiers of research and thus write with the authority that comes from personal involvement. This series is designed to provide the necessary background, theory, and working information on particular topics for physicists (and chemists), engineers, and advanced students. Furthermore, these critical reviews are definitive and intensive enough to be used by a specialist in some aspect of the topic wishing to update his knowledge on related areas. The publication periods are as short as possible to keep pace with the speed of scientific advance, and in this respect the new books are comparable with scientific journals. The first volume deals with dye lasers, the history of their development and their potential applications. Under the editorship of F. P. ScHAFER six authors, all of whom have done pioneering work on dye lasers, review some major aspects. The editor introduces and discusses the principles of dye-laser operation in general, B. B. SNAVELY describes cw operation, and C. V. SHANK and E. P. IPPEN deal with mode-locking behavior. The basic laser material is a dye solution, and its chemical properties and structure are set forth by K. H. DREXHAGE. The broad
VI Introduction spectrum of potential applications is outlined by T. W. HANSCH, who also touches briefly on the exciting field of laser spectroscopy, a most important application to which a forthcoming volume is devoted. The treatment, being tutorial in nature, is suitable both for graduate students and for scientists working in the dye-laser field or applying a dye laser in another research discipline. The book will also prove to be an indispensable and handy source of information for the specialist. The literature is reviewed up to spring 1973, and the list of additional references (which cites the titles of articles) extends to summer 1973. This is proof of an amazingly short publication period for a 300-page book. Heidelberg, October 1973 HELMUT K. V. LOTSCH
Contents 1. Principles of Dye Laser Operation. By FRITZ P. SCHAFER (with 53 Figures) Historical................ Organization of the Book......... 1.1. General Properties of Organic Compounds 1.2. Light Absorption by Organic Dyes 1.3. Deactivation Pathways for Excited Molecules 1.4. Laser-Pumped Dye Lasers.... 1.4.1. Oscillation Condition..... 1.4.2. Practical Pumping Arrangements 1.4.3. Time Behavior and Spectra 1.5. Flashlamp-Pumped Dye Lasers 1.5.1. Triplet Influence.... 1.5.2. Practical Pumping Arrangements 1.5.3. Time Behavior and Spectra 1.6. Wavelength-Selective Resonators for Dye Lasers 1. 7. Dye-Laser Amplifiers 1.8. Outlook................. 1 5 6 9 28 32 32 37 44 54 54 60 64 66 79 83 2. Continuous-Wave Dye Lasers. By B. B. SNAVELY(with 18 Figures) 2.1. Gain Analysis of the cw Dye-Laser.... 91 2.1.1. Analysis at Laser Threshold.... 91 2.1.2. Gain Analysis above Laser Threshold 98 2.2. Tuning of the cw Dye Laser.... 103 2.3. Performance of Experimental Systems 114 2.4. Conclusion........... 119 3. Mode-Locking of Dye Lasers. By C. V. SHANK and E. P. IPPEN (with 11 Figures) 3.1. General Background 121 3.2. Pulsed Dye Lasers 128 3.3. Continuous Dye Lasers 135 3.4. Discussion of Short Pulse Formation 141
VIII Contents 4. Structure and Properties of Laser Dyes. By K. H. DREXHAGE (with 6 Figures) 4.1. Physical Properties of Laser Dyes 144 4.2. Internal Conversion S 1 -+S 0 147 4.2.1. Structural Mobility 147 4.2.2. Hydrogen Vibrations 149 4.2.3. Other Intramolecular Quenching Processes 150 4.2.4. Determination of Fluorescence Yields 151 4.3. Intersystem Crossing S 1 -+ T 1...... 152 4.3.1. Dependence on n-electron Distribution 152 4.3.2. Heavy-Atom Substituents.... 154 4.3.3. Determination of Triplet Yields 155 4.4. Light Absorption in the States $ 1 and T 1 156 4.5. Environmental Effects........ 157 4.5.1. Fluorescence Quenching by Charge Transfer Interactions........ 157 4.5.2. Quenching by Energy Transfer 158 4.5.3. External Heavy-Atom Effect 158 4.5.4. Aggregation of Dye Molecules 158 4.5.5. Excited State Reactions 160 4.6. Coumarin Derivatives 161 4.6.1. Absorption and Fluorescence 161 4.6.2. Acid-Base Equilibria 164 4.7. Xanthene Dyes..... 167 4.7.1. Absorption Spectra 167 4.7.2. Fluorescence Properties 171 4.8. Newer Classes of Efficient Laser Dyes 172 4. 8.1. Oxazine Dyes........ 172 4.8.2. Carbon-Bridged Dyes.... 175 4.8.3. Naphthofluorescein and Related Dyes 176 4.9. Other Efficient Laser Dyes.... 4.1 0. Purity and Chemical Identity of Dyes 4.11. Concluding Remarks 177 177 178 5. Applications of Dye Lasers. By THEODOR W. HANSCH (with 26 Figures) Properties of Dye Lasers..... Laser Applications..... 5.1. Light Absorption and Scattering 5.1.1. Absorption Spectroscopy 194 196 197 198
Contents IX 5.1.2. Selective Dye-Laser Quenching 199 5.1.3. Raman Scattering 201 5.1.4. Resonance Fluorescence 203 5.1.5. Trace Analysis, Pollution Detection 204 5.1.6. LIDAR, Resonant Atmospheric Scattering 205 5.1.7. Measurements of Lifetimes and Relaxation Rates 207 5.1.8. Resonant Radiation Pressure, Atomic Beam Deflection 208 5.2. Selective Excitations 209 5.2.1. Optical Pumping 209 5.2.2. Excited-State Spectroscopy 210 5.2.3. Photomagnetism 211 5.2.4. Pumping of Laser Transitions 211 5.2.5. Photoionization 213 5.2.6. Photodetachment 215 5.3. Nonlinear Spectroscopy 217 5.3.1. Saturation Spectroscopy 217 5.3.2. Coherent Transient Effects 220 5.3.3. Nonlinear Susceptibilities 222 5.3.4. Stimulated Light Scattering 224 5.4. Other Spectroscopic Applications 225 5.4.1. Level-Crossing Spectroscopy 226 5.4.2. Quantum-Beat Spectroscopy 226 5.4.3. Heterodyne Spectroscopy 228 5.5. Generation of Tunable UV and IR by Nonlinear Frequency Mixing............. 228 5.5.1. Harmonic and Sum Frequency Generation 229 5.5.2. Difference Frequency Generation 233 5.5.3. Pumping of Optical Parametric Oscillators 235 5.6. Photochemistry, Isotope Separation 236 5.6.1. Fast Photochemical Reactions 237 5.6.2. Two-Step Photoionization 238 5.6.3. Two-Step Photodissociation 238 5.6.4. Photopredissociation 239 5.7. Dye-Laser Applications in Biology. 239 5. 7.1. Photolysis of Biological Molecules: Reaction Kinetics 240 5.8. Applications in Medicine 241 5.9. Holography 242 5.9.1. Holographic Contour Mapping 243
X Contents 5.10. Communications, Integrated Optics....... 246 5.10.1. Active Waveguides: Thin-Film Dye Lasers. 247 5.10.2. Dye Lasers with Distributed Feedback.. 249 5.11. Light Amplification............. 252 5.11.1. Dye-Laser Oscillator-Amplifier Systems. 254 5.11.2. Intensity Stabilization by Saturated Amplification 255 5.11.3. Dye-Laser Amplifiers with Feedback. 256 5.11.4. Image Amplification. 258 References.......... 260 Additional References with Titles Subject Index......... 271. 275
Contributors DREXHAGE, K. H., Research Laboratories, Eastman Kodak Company, Rochester N. Y. 14650/USA HXNSCH, THEODOR W., Department of Physics, Stanford University, Stanford CA 94305/USA IPPEN, E. P., Bell Telephone Laboratories, Holmdel N. J. 07733/USA ScHAFER, FRITZ P., Max-Planck-Institut fiir Biophysikalische Chemie, D-3400 Gottingen/Fed. Rep. of Germany SHANK, C. V., Bell Telephone Laboratories, Holmdel N.J. 07733/USA SNAVELY, BENJAMIN B., University of California, Lawrence Radiation Laboratory, Livermore, CA 24 550/USA