Distributed feedback laser diodes and optical tunable filters

344 Pages·2003·4.98 MB·English

by  Ghafouri-Shiraz, H

Distributed Feedback Laser Diodes and
Optical Tunable Filters
Dr. H. Ghafouri–Shiraz
The University of Birmingham, UK
and
Nanyang Technological University, Singapore

Distributed Feedback Laser Diodes and
Optical Tunable Filters

Distributed Feedback Laser Diodes and
Optical Tunable Filters
Dr. H. Ghafouri–Shiraz
The University of Birmingham, UK
and
Nanyang Technological University, Singapore
Copyright#2003 JohnWiley&SonsLtd,TheAtrium,SouthernGate,Chichester,
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LibraryofCongressCataloging-in-PublicationData
Ghafouri–Shiraz,H.
Distributedfeedbacklaserdiodesandopticaltunablefilters/H.Ghafouri–Shiraz.
p. cm.
Includesbibliographicalreferencesandindex.
ISBN0-470-85618-1(alk.paper)
1.Lightemittingdiodes.2.Solid-statelasers.3.Tunablelasers.4.Lightfilters. I.Title.
TK7871.89.L53G43 2003
621.3606–dc21 2003050194
BritishLibraryCataloguinginPublicationData
AcataloguerecordforthisbookisavailablefromtheBritishLibrary
ISBN0-470-85618-1
Typesetin10/12ptTimesbyThomsonPress(India)Limited,NewDelhi
PrintedandboundinGreatBritainbyTJInternational,Padstow,Cornwall
Thisbookisprintedonacid-freepaperresponsiblymanufacturedfromsustainableforestry
inwhichatleasttwotreesareplantedforeachoneusedforpaperproduction.
This book is dedicated to
MyFather,thelateHajiMansour,fortheuncompromisingprinciplesthatguidedhislife
and for his profound influence and inspiration.
My Mother, Rahmat, for leading her children into intellectual pursuits.
My Supervisor, the late Professor Takanori Okoshi, for his continuous guidance,
encouragement, inspiring discussion and moral support. A distinguished scientist and a
great teacher who made me aware of the immense potential of optical fibre
communications.
MyWife,Maryam,forherunderstandingsupport,affectionandmagnificentdevotionto
her family. My constant companion and best friend, she has demonstrated incredible
patience and understanding during the rather painful process of writing this book while
maintaining a most pleasant, cheerful and comforting home.
My Children, Elham, Ahmad-Reza and Iman, for making everything worthwhile.
To all of my research and undergraduate students since 1987, for their excellent and
fruitful research work, and for many stimulating discussions, which encouraged and
motivated me to write this book.

Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Glossary of Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xviii
Glossary of Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix
1. An Introduction to Optical Communication Systems. . . . . . . . . . . . . . . . 1
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Historical Progress. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Optical Fibre Communication Systems. . . . . . . . . . . . . . . . . . . . . . . . 4
1.3.1 Intensity Modulation with a Direct Detection Scheme . . . . . . . . 5
1.3.2 Coherent Detection Schemes. . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 System Requirements for High-Speed Optical
Coherent Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.4.1 Spectral Purity Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.4.2 Spectral Linewidth Requirements. . . . . . . . . . . . . . . . . . . . . . 18
1.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
1.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2. Principles of Distributed Feedback Semiconductor Laser Diodes:
Coupled Wave Theory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.2 Basic Principle of Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.2.1 Absorption and Emission of Radiation. . . . . . . . . . . . . . . . . . 32
2.2.2 The Einstein Relations and the Concept of
Population Inversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2.2.3 Dispersive Properties of Atomic Transitions . . . . . . . . . . . . . . 36
2.3 Basic Principles of Semiconductor Lasers. . . . . . . . . . . . . . . . . . . . . 38
2.3.1 Population Inversion in Semiconductor Junctions. . . . . . . . . . . 38
2.3.2 Principle of the Fabry–Perot Etalon. . . . . . . . . . . . . . . . . . . . 41
2.3.3 Structural Improvements in Semiconductor Lasers. . . . . . . . . . 43
2.3.4 Material Gain in Semiconductor Lasers . . . . . . . . . . . . . . . . . 45
2.3.5 Total Radiative Recombination Rate in Semiconductors. . . . . . 48
2.4 Coupled Wave Equations in Distributed Feedback Semiconductor
Laser Diodes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
2.4.1 A Purely Index-coupled DFB Laser Diode . . . . . . . . . . . . . . . 56
2.4.2 A Mixed-coupled DFB Laser Diode. . . . . . . . . . . . . . . . . . . . 57
2.4.3 A Gain-coupled or Loss-coupled DFB Laser Diode. . . . . . . . . 58
2.5 Coupling Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2.5.1 A Structural Definition of the Coupling Coefficient for
DFB Semiconductor Lasers. . . . . . . . . . . . . . . . . . . . . . . . . . 60