Table Of Content

NEW AGE THIRD EDITION and Non-Linear Optics B.B. Laud NEW AGE INTERNATIONAL PUBLISHERS Lasers and Non-Linear Optics This page intentionally left blank Lasers and Non-Linear Optics (THIRD EDI TION) B.B. Laud Professor and Head Department of Physics Marathwada University Aurangabad, Maharashtra Pua. rtMHG FOB OM aCMO NEW AGE INTERNATIONAL (P) LIMITED, PUBLISHERS New Delhi • Bangalore • Chennai • Cochin • Guwahati • Hyderabad Jalandhar • Kolkata • Lucknow • Mumbai • Ranchi Visit us at w5vw.newagepublishers.com Copyright ©2011. 1991.1985. New Age International (P) Ltd., Publishers Published by New Age International (P) Ltd., Publishers All rights reserved. No pan of this ebook may be reproduced in any form, by photostat, microfilm, xerography, or any other means, or incorporated into any information retrieval system, electronic or mechanical, without the written permission of tire publisher. All inquiries should be emailed to rightstPnewagepublishers.com ISBN (13) : 978 81 224 3488 0 Pl HI ISHING FOR ONE WORLD NEW AGE INTERNATI ONAl. (P) LIMITED. PUBLISHERS 4835/24. Ansari Road. Daryaganj. New Delhi 110002 Visit us at www.newagepubllshers.com PREFACE TO THE THIRD EDITION In this edition of the book, although the headings appear similar (except in a couple of cases), the revision lias been extensive. The layout and style pattern have been modified to give a attractive look. A number of alterations have been made and some of the material has been rearranged. Some of the sections have been expanded: while others have been largely rewritten to improve clarity and generality. Mathematical treatment has been simplified wherever possible. A more general discussion on laser pumping and resonators has been provided. The main change is the extension of the book to cover some important topics such as: coherent state description of the electromagnetic field, hydrogen maser, electroionisation, gas-dynamic lasers, distributed feedback laser. Doppler- free-two photon spectroscopy, laser cooling and trapping of neutral atoms, etc. In all thirteen new sections have been added to take account of the recent developments in the field. With these additions the book should be suitable for a wider circle of readers. Every effort has been made to make the book error free from the previous edition. B.B. LAUD This page intentionally left blank PREFACE TO THE FIRST EDITION The advent of the laser as a primary source of power is one of the most significant events of the century. Since the announcement of the first laser, the subject of laser physics has developed at a rapid rate and lasers of wide variety Itave been constructed. Amazing advances have been made by applying this new tool in spectroscopy. A new area — nonlinear optics — has now come to the fore and is in a stage of rapid expansion. I have attempted to encompass in this book the wide area joining laser physics and nonlinear optics. It is impossible to give a comprehensive account of the total variety of up-to-date lasers while keeping the book to a reasonable length and. hence a considerable amount of selection has been necessary. I have endeavoured to introduce all the important physical principles involved in laser devices and tried to give a consistent treatment of each. Original experiments have been described in detail and recent modifications have been discussed briefly. The knowledge of the fundamental processes taking place in laser devices should help the reader to understand the design and operation of newly developed devices. Tliroughout tlie book the treatment has been kept as simple as possible and understandable to readers with variety of backgrounds. Mathematical background that the graduate students usually have is assumed. Some familiarity with the elements of electromagnetic theory and of spectroscopy will be helpful. The general level of the book is such that a graduate student should have no trouble with it and. I hope, they will find much of it digestable and stimulating. In Chapters 2 (Einsteins theory). 3 (Interaction of radiation with matter) and 5 (Theory of some simple optical processes). 1 have provided a concise account of the basic physics on which the operation of laser depends. It should prepare the way. by easy stages, for the formal development of lasers. Attempt lias been made to collect in a compact and a unified form, some of the material in nonlinear optics widely scattered in various journals, which Viii LASERS AND NONLINEAR OPTICS is needed for understanding of the current research work. Papers and articles published up to 1983 and which were accessible, have been taken note of. In Chapter 16. certain new and somewhat dramatic problems of current interest have been described in detail. It goes without saying that the selection of material to illustrate the achievements in non-linear optics must inevitably be subjective. But I believe that the problems discussed should be of interest to readers who wish to know what is new in non-linear optics. Besides, the ideas and concepts developed in these problems will prove to be of wider, more general, interest for those working in the allied fields. It is hoped that the approach adopted in the book will help the reader to acquire the new concepts and advanced methods and give him a sort of overall perspective necessary to enable him to continue with confidence further independent research. The book, therefore, if it fulfills its purpose, should be useful to a wide variety of people: not only to the students in the University, but also to research workers in the field of physics and chemistry and to engineers and scientists working in other disciplines. Some applications of wide interest are discussed in the last chapter. It is fitting to record here my indebtedness to authors of original papers, books and writers of review articles. I have drawn freely on the original papers and consulted many well-written expositions of laser physics and non-linear optics by celebrated authors. Throughout the book. 1 have attempted to give full references to all those authors whose work is quoted and full list of references, in alphabetical order, is included at the end of the book. My thanks are due to a number of friends and former students who took pains to make available to me the literature which would not have been easily accessible. B.B. LAUD CONTENTS Preface to the Third Edition v Preface to the First Edition vii 1. Introduction 1-7 1.1 Directionality 3 1.2 Intensity 4 1.3 Monochromacity 5 1.4 Coherence 6 2. Einstein's Quantum Theory of Radiation 8-15 2.1 Einstein Coefficients 8 2.2 Momentum Transfer 12 2.3 Life-time 13 2.4 Possibility of Amplification 14 3. Interaction of Radiation with Matter 16-44 3.1 Time Dependent Perturbation Theory 17 3.2 Electric Dipole Interaction 20 3.3 Quantum Electrodynamics 26 3.3.1 Creation and Annihilation Operators 26 3.3.2 Fock States 29 3.3.3 Quantization of the Field 29 3.3.4 Zero-point Energy 33 3.3.5 Coherent-state Description of the Electromagnetic Field 34 3.3.6 Interaction of Radiation with Matter 38 4. Masers 45-54 4.1 The Two-level Maser System Ammonia Maser 46 4.2 Hydrogen Maser 50 4.3 The Three-level Maser System 52