Fiber-Optic Communication Systems

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1 Fiber-Optic Communication Systems Second Edition GOVIND P. AGRAWAL The Institute of Optics University of Rochester Rochester, NY A WILEY-iNTERSCIENCE PUBLICATION JOHN WILEY & SONS, INC. NEW YORK / CHICHESTER / WEINHEIM / BRISBANE / SINGAPORE / TORONTO

Contents PREFACE PREFACE TO THE FIRST EDITION vii ix 1 Introduction 1 1.1 Historical Perspective 1 1.1.1 Need for Fiber-Optic Communications 2 1.1.2 Five generations of Lightwave Systems 4 1.

2 Contents PREFACE PREFACE TO THE FIRST EDITION vii ix 1 Introduction Historical Perspective Need for Fiber-Optic Communications Five generations of Lightwave Systems Basic Concepts Analog and Digital Signals Channel Multiplexing Modulation Formats Optical Communication Systems Lightwave System Components Optical Fibers as a Communication Channel Optical Transmitters Optical Receivers Channel Capacity 19 Problems 20 References 21 2 Optical Fibers Geometrical-Optics Description Step-Index Fibers Graded-Index Fibers Wave Propagation Maxwell's Equations 30 XI

CONTENTS 2.2.2 Fiber Modes 2.2.3 Single-Mode Fibers 2.3 Dispersion in Single-Mode Fibers 2.3.1 Group-Velocity Dispersion 2.3.2 Material Dispersion 2.3.3 Waveguide Dispersion 2.3.4 Higher-Order Dispersion 2.

3 CONTENTS Fiber Modes Single-Mode Fibers 2.3 Dispersion in Single-Mode Fibers Group-Velocity Dispersion Material Dispersion Waveguide Dispersion Higher-Order Dispersion Polarization-Mode Dispersion 2.4 Dispersion-Induced Limitations Basic Propagation Equation Chirped Gaussian Pulses Limitations on the Bit Rate Fiber Bandwidth 2.5 Fiber Loss Attenuation Coefficient Material Absorption Rayleigh Scattering Waveguide Imperfections 2.6 Nonlinear Optical Effects Stimulated Light Scattering Nonlinear Refraction Four-Wave Mixing 2.7 Fiber Manufacturing Design Issues Fabrication Methods Cables and Connectors Problems References Optical Transmitters 3.1 Basic Concepts Emission and Absorption Rates p-n Junctions Nonradiative Recombination Semiconductor Materials 3.2 Light-Emitting Diodes Light-Current Characteristics Spectral Distribution Modulation Response LED Structures 3.3 Semiconductor Lasers Optical Gain

CONTENTS xiii 3.3.2 Feedback and Laser Threshold 95 3.3.3 Laser Structures 97 3.3.4 Laser Modes 100 3.3.5 Single-Longitudinal-Mode Operation 104 3.3.6 Light-Current Characteristics ПО 3.3.7 Modulation Response 113 3.

4 CONTENTS xiii Feedback and Laser Threshold Laser Structures Laser Modes Single-Longitudinal-Mode Operation Light-Current Characteristics ПО Modulation Response Laser Noise Transmitter Design Source-Fiber Coupling Optical Feedback Driving Circuitry Optoelectronic Integration Reliability and Packaging 128 Problems 130 References Optical Receivers Basic Concepts Photodetector Design p-n Photodiodes p-i-n Photodiodes Avalanche Photodiodes MSM Photodetectors Receiver Design Front End Linear Channel Data Recovery Integrated Receivers Receiver Noise Noise Mechanisms p-i-n Receivers APD Receivers Receiver Sensitivity Bit-Error Rate Minimum Received Power Quantum Limit of Photodetection Sensitivity Degradation Extinction Ratio Intensity Noise Timing Jitter Receiver Performance 182 Problems 185 References 187

xiv CONTENTS 5 System Design and Performance 5.1 System Architectures 5.1.1 Point-to-Point Links 5.1.2 Broadcast and Distribution Networks 5.1.3 Local-Area Networks 5.2 Design Guidelines 5.2.1 Loss-Limited Lightwave Systems 5.

5 xiv CONTENTS 5 System Design and Performance 5.1 System Architectures Point-to-Point Links Broadcast and Distribution Networks Local-Area Networks 5.2 Design Guidelines Loss-Limited Lightwave Systems Dispersion-Limited Lightwave Systems Long-Haul Systems with In-Line Amplifiers Telecommunication Fiber Links 5.3 System Design Power Budget Rise-Time Budget 5.4 Sources of Power Penalty Modal Noise Dispersion Broadening Mode-Partition Noise Frequency Chirping Reflection Feedback and Noise 5.5 Computer-Aided Design Problems References 6 Coherent Lightwave Systems 6.1 Basic Concepts Local Oscillator Homodyne Detection Heterodyne Detection Signal-to-Noise Ratio 6.2 Modulation Formats ASK Format PSK Format FSK Format 6.3 Demodulation Schemes Heterodyne Synchronous Demodulation Heterodyne Asynchronous Demodulation 6.4 Bit-Error Rate Synchronous ASK Receivers Synchronous PSK Receivers Synchronous FSK Receivers Asynchronous ASK Receivers

CONTENTS xv 6.4.5 Asynchronous FSK Receivers 259 6.4.6 Asynchronous DPSK Receivers 260 6.5 Sensitivity Degradation 261 6.5.1 Phase Noise 261 6.5.2 Intensity Noise 263 6.5.3 Polarization Mismatch 266 6.

6 CONTENTS xv Asynchronous FSK Receivers Asynchronous DPSK Receivers Sensitivity Degradation Phase Noise Intensity Noise Polarization Mismatch Fiber Dispersion Other Limiting Factors System Performance Asynchronous Heterodyne Systems Synchronous Heterodyne Systems Homodyne Systems Field Trials 274 Problems 275 References Multichannel Lightwave Systems WDM Lightwave Systems High-Capacity Point-to-Point Links Broadcast and Distribution Networks Multiple-Access WDM Networks WDM Components Tunable Optical Filters Multiplexers and Demultiplexers Add/Drop Multiplexers and Filters Broadcast Star Couplers Wavelength Routers Optical Cross-Connects Wavelength Converters WDM Transmitters and Receivers System Performance Issues Linear Crosstalk Nonlinear Crosstalk Other Design and Performance Issues Time-Division Multiplexing Channel Multiplexing Channel Demultiplexing System Performance Subcarrier Multiplexing Analog SCM Lightwave Systems Digital SCM Lightwave Systems Multiwavelength SCM Lightwave Systems 343

xvi CONTENTS 7.6 Code-Division Multiplexing 345 Problems 347 References 349 8 Optical Amplifiers 361 8.1 Basic Concepts 361 8.1.1 Gain Spectrum and Bandwidth 362 8.1.2 Gain Saturation 364 8.1.3 Amplifier Noise 365 8.

7 xvi CONTENTS 7.6 Code-Division Multiplexing 345 Problems 347 References Optical Amplifiers Basic Concepts Gain Spectrum and Bandwidth Gain Saturation Amplifier Noise Amplifier Applications Semiconductor Laser Amplifiers Amplifier Design Amplifier Characteristics Multichannel Amplification Pulse Amplification System Applications Fiber Raman Amplifiers Raman Gain and Bandwidth Gain Saturation Amplifier Performance Fiber Brillouin Amplifiers Brillouin Gain and Amplifier Bandwidth Gain Saturation Amplifier Performance Doped-Fiber Amplifiers Pumping Requirements Gain Spectrum Gain Characteristics Amplifier Noise Multichannel Amplification Ultrashort Pulse Amplification Pr-Doped Fiber Amplifiers Distributed-Gain Amplifiers System Applications Optical Preamplifiers Power Boosters Local-Area-Network Amplifiers Cascaded In-Line Amplifiers 410 Problems 415 References 416

CONTENTS xvii Dispersion Compensation 425 9.1 Dispersion Limitations 425 9.2 Postcompensation Techniques 427 9.3 Precompensation Techniques 428 9.3.1 Pre-Chirping 428 9.3.2 Pure Frequency Modulation 431 9.

8 CONTENTS xvii Dispersion Compensation Dispersion Limitations Postcompensation Techniques Precompensation Techniques Pre-Chirping Pure Frequency Modulation Duobinary Coding Amplifier-Induced Chirp Fiber-Induced Chirp High-Dispersion Fibers Optical Equalizing Filters Fabry-Perot Interferometers Mach-Zehnder Interferometers Fiber Bragg Gratings Uniform-Period Gratings Chirped Fiber Gratings Chirped Mode Couplers Optical Phase Conjugation Principle of Operation Compensation of Self-Phase Modulation Generation of Phase-Conjugated Signal Effect of Periodic Amplification Broadband Compensation Time-Division Multiplexing Wavelength-Division Multiplexing Long-Haul Lightwave Systems 457 Problems 459 References 461 Soliton Communication Systems Fiber Solitons Nonlinear Schrödinger Equation Fundamental and Higher-Order Solitons Dark Solitons Soliton-Based Communications Information Transmission with Solitons Soliton Interaction Frequency Chirp Soliton Transmitters

xviii CONTENTS A В С Index 10.2.5 Loss-Induced Soliton Broadening 10.2.6 Soliton Amplification 10.3 Soliton System Design 10.3.1 Average-Soliton Regime 10.3.2 Amplifier Noise 10.3.3 Timing Jitter 10.

9 xviii CONTENTS A В С Index Loss-Induced Soliton Broadening Soliton Amplification 10.3 Soliton System Design Average-Soliton Regime Amplifier Noise Timing Jitter Timing-Jitter Control Experimental Progress 10.4 High-Capacity Soliton Systems Quasi-Adiabatic Regime Polarization-Division Multiplexing Distributed Amplification Dispersion-Decreasing Fibers Dispersion Management 10.5 WDM Soliton Systems Soliton Collisions Collision-Induced Frequency Shifts Collision-Induced Limitations Timing Jitter Dispersion Management Problems References International System of Units Decibel Units Acronyms

Optical Fibers p. 1 Basic Concepts p. 1 Step-Index Fibers p. 2 Graded-Index Fibers p. 4 Design and Fabrication p. 6 Silica Fibers p.

Preface p. xiii Optical Fibers p. 1 Basic Concepts p. 1 Step-Index Fibers p. 2 Graded-Index Fibers p. 4 Design and Fabrication p. 6 Silica Fibers p. 6 Plastic Optical Fibers p. 9 Microstructure Optical