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FIBER OPTIC COMMUNICATIONS FIBER OPTIC COMMUNICATIONS FUNDAMENTALS AND APPLICATIONS ShivaKumarandM.JamalDeen DepartmentofElectricalandComputerEngineering,McMasterUniversity,Canada Thiseditionfirstpublished2014 ©2014JohnWiley&Sons,Ltd Registeredoffice JohnWiley&SonsLtd,TheAtrium,SouthernGate,Chichester,WestSussex,PO198SQ,UnitedKingdom Fordetailsofourglobaleditorialoffices,forcustomerservicesandforinformationabouthowtoapplyforpermissiontoreusethe copyrightmaterialinthisbookpleaseseeourwebsiteatwww.wiley.com. TherightoftheauthortobeidentifiedastheauthorofthisworkhasbeenassertedinaccordancewiththeCopyright,Designsand PatentsAct1988. Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmitted,inanyformorbyany means,electronic,mechanical,photocopying,recordingorotherwise,exceptaspermittedbytheUKCopyright,DesignsandPatents Act1988,withoutthepriorpermissionofthepublisher. 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LibraryofCongressCataloging-in-PublicationData Kumar,Shiva,Dr. Fiberopticcommunications:fundamentalsandapplications/ShivaKumarandM.JamalDeen. pagescm Includesbibliographicalreferencesandindex. ISBN978-0-470-51867-0(cloth) 1.Opticalfibercommunication.2.Fiberoptics.I.Deen,M.Jamal.II.Title. TK5103.592.F52K8162014 621.36′92–dc23 2013043803 AcataloguerecordforthisbookisavailablefromtheBritishLibrary. ISBN:9780470518670 Setin10/12ptTimesLTStdbyLaserwordsPrivateLimited,Chennai,India 1 2014 MJD To my late parents, Mohamed and Zabeeda Deen SK To my late parents, Saraswathi and Narasinga Rao Contents Preface xv Acknowledgments xvii 1 ElectromagneticsandOptics 1 1.1 Introduction 1 1.2 Coulomb’sLawandElectricFieldIntensity 1 1.3 Ampere’sLawandMagneticFieldIntensity 3 1.4 Faraday’sLaw 6 1.4.1 MeaningofCurl 7 1.4.2 Ampere’sLawinDifferentialForm 9 1.5 Maxwell’sEquations 9 1.5.1 Maxwell’sEquationinaSource-FreeRegion 10 1.5.2 ElectromagneticWave 10 1.5.3 Free-SpacePropagation 11 1.5.4 PropagationinaDielectricMedium 12 1.6 1-DimensionalWaveEquation 12 1.6.1 1-DimensionalPlaneWave 15 1.6.2 ComplexNotation 16 1.7 PowerFlowandPoyntingVector 17 1.8 3-DimensionalWaveEquation 19 1.9 ReflectionandRefraction 21 1.9.1 Refraction 22 1.10 PhaseVelocityandGroupVelocity 26 1.11 PolarizationofLight 31 Exercises 31 FurtherReading 34 References 34 2 OpticalFiberTransmission 35 2.1 Introduction 35 2.2 FiberStructure 35 2.3 RayPropagationinFibers 36 2.3.1 NumericalAperture 37 viii Contents 2.3.2 Multi-ModeandSingle-ModeFibers 39 2.3.3 DispersioninMulti-ModeFibers 39 2.3.4 Graded-IndexMulti-ModeFibers 42 2.4 ModesofaStep-IndexOpticalFiber* 44 2.4.1 GuidedModes 46 2.4.2 ModeCutoff 51 2.4.3 EffectiveIndex 52 2.4.4 2-DimensionalPlanarWaveguideAnalogy 53 2.4.5 RadiationModes 54 2.4.6 ExcitationofGuidedModes 55 2.5 PulsePropagationinSingle-ModeFibers 57 2.5.1 PowerandthedBmUnit 60 2.6 ComparisonbetweenMulti-ModeandSingle-ModeFibers 68 2.7 Single-ModeFiberDesignConsiderations 68 2.7.1 CutoffWavelength 68 2.7.2 FiberLoss 69 2.7.3 FiberDispersion 74 2.7.4 DispersionSlope 76 2.7.5 PolarizationModeDispersion 78 2.7.6 SpotSize 79 2.8 Dispersion-CompensatingFibers(DCFs) 79 2.9 AdditionalExamples 81 Exercises 89 FurtherReading 91 References 91 3 Lasers 93 3.1 Introduction 93 3.2 BasicConcepts 93 3.3 ConditionsforLaserOscillations 101 3.4 LaserExamples 108 3.4.1 RubyLaser 108 3.4.2 SemiconductorLasers 108 3.5 Wave–ParticleDuality 108 3.6 LaserRateEquations 110 3.7 ReviewofSemiconductorPhysics 113 3.7.1 ThePNJunctions 118 3.7.2 SpontaneousandStimulatedEmissionatthePNJunction 120 3.7.3 DirectandIndirectBand-GapSemiconductors 120 3.8 SemiconductorLaserDiode 124 3.8.1 HeterojunctionLasers 124 3.8.2 RadiativeandNon-RadiativeRecombination 126 3.8.3 LaserRateEquations 126 3.8.4 Steady-StateSolutionsofRateEquations 128 3.8.5 Distributed-FeedbackLasers 132 *Advancedmaterialwhichmayneedadditionalexplanationforundergraduatereaders