Copyright © 2004 Marcel Dekker, Inc. The Japanese edition of this book was published in the Kyoritsu Advanced Optoelectronics Series (KyoritsuShuppan, Tokyo,1998). Although great care has been taken to provide accurate and current information, neither the author(s) nor the publisher, nor anyone else associated with this publication, shall be liable for any loss, damage, or liability directly or indirectly caused or alleged to be caused by this book. The material contained herein is not intended toprovide specific adviceorrecommendations forany specificsituation. Trademark notice: Product or corporate names may be trademarks or registered trademarks and are used only for identification and explanation without intent to infringe. Library ofCongress Cataloging-in-Publication Data A catalogrecord for thisbookis availablefrom the Libraryof Congress. ISBN:0-8247-5373-9 Thisbookis printedonacid-free paper. 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Current printing (last digit): 10 9 8 7 6 5 4 3 2 1 PRINTED IN THEUNITED STATESOF AMERICA Copyright © 2004 Marcel Dekker, Inc. Copyright © 2004 Marcel Dekker, Inc. Copyright © 2004 Marcel Dekker, Inc. Copyright © 2004 Marcel Dekker, Inc. Copyright © 2004 Marcel Dekker, Inc. Preface Semiconductor lasers are among the most important optoelectronics devices. Remarkable development has been accomplished in the three decades since the first achievement in room-temperature continuous oscillation, which opened the possibility of practical applications of semiconductor lasers. Today, various types of semiconductor lasers are mass-produced and widely used as coherent light sources for a variety of applications, including optical fiber communication systems and optical disk memory systems. Advanced functions and high performance have been realized through distributed feedback lasers and quantum well lasers following the development of Fabry–Perot-type lasers. Accordingly, new applications previously unfeasible (or difficult with other conventional lasers)havebeenfound,andthereplacementofgasandsolid-statelasersby compact and economical semiconductor lasers is in progress. Thus, semiconductor lasers are indispensable devices of increasing importance. Extensive research and development is being conducted toward specific applications. Remarkable progress is also being made in optoelectronic integrated circuits and integrated photonic devices using semiconductor lasers as the main component. Implementation and advanced applications of semiconductor lasers require a deep understanding, and high technological expertise, in subareas including materials, crystal growth, device design, microfabrication, and devicecharacterization(allofwhichcomprisethefieldcalledsemiconductor laser engineering). There already exist a number of authoritative books on semiconductor lasers, as given in the references in Chapter 1. In Chapter 2, the fundamental quantum theory on the interaction of electrons and photons is outlined and summarized in a form that is convenient for the understanding and analysis of semiconductor lasers. Chapter 3 deals with stimulated emission in semiconductors as one of the most important principles for implementation of semiconductor lasers, and explains the basic theory and characteristics of light amplification. Chapter 4 covers Copyright © 2004 Marcel Dekker, Inc. theoretical discussions on electron–photon interactions and stimulated emission, and considers characteristics of optical waveguide resonators for laser oscillator implementation. In Chapter 6, rate equation analysis of semiconductor lasers is presented to clarify and explain the static and dynamic characteristics of semiconductor lasers using Fabry–Perot-type semiconductor lasers as a prototype device. Chapter 7 is devoted to distributed feedback lasers and distributed Bragg reflector lasers,which are dynamicsingle-modelasersandallowadvancedperformance.InChapter8, semiconductor laser amplifiers are discussed. The Appendixes provide important theoretical topics and experimental techniques. Thechapterswerecarefullycheckedformutualconsistencyandclarity of context. Efforts were made to give a comprehensive explanation of mathematical formulae including the procedure of the deduction and physicalmeanings,ratherthansimpledescriptionsoftheresults,inorderto ensure full understanding without skipping basic principles or referring to other materials. Almost all the formulae are in such a form that they can actually be used by the readers for analysis and design. It will give me great satisfaction if this book is helpful to researchers, engineers, and students interested in semiconductor lasers. Finally, I would liketothankthestaffsofKyoritsuPub.,Ltd.,andMarcelDekker,Inc.,for their cooperation. Toshiaki Suhara Copyright © 2004 Marcel Dekker, Inc. Contents 1. Introduction 1.1 Principles and Device Structures of Semiconductor Lasers 1.2 Materials for Semiconductor Lasers 1.3 Features of Semiconductor Injection Lasers 1.4 Applications of Semiconductor Lasers References 2. Interaction of Electrons and Photons 2.1 Quantization of Optical Waves and Photons 2.2 Interactions of Electrons and Photons 2.3 Absorption and Emission of Photons 2.4 Population Inversion and Light Amplification References 3. Stimulated Emission and Optical Gain in Semiconductors 3.1 Band Structure of Semiconductors and Stimulated Emission 3.2 Direct-Transition Model 3.3 Gaussian Halperin–Lax Band-Tail Model with the Stern Energy-Dependent Matrix Element 3.4 Gain Spectrum and Gain Factor 3.5 Spontaneous Emission and Injection Current Density 3.6 Density Matrix Analysis References 4. Stimulated Emission in Quantum Well Structures 4.1 Electron State in Quantum Well Structures 4.2 Direct-Transition Model 4.3 Gain Spectrum and Gain Factor Copyright © 2004 Marcel Dekker, Inc.