Description
Book SynopsisTable of ContentsPreface xvi
1 Introduction 1
1.1 Historical Perspective 1
1.1.1 Need for Fiber-Optic Communications 2
1.1.2 Evolution of Lightwave Systems 4
1.2 Basic Concepts 8
1.2.1 Analog and Digital Signals 8
1.2.2 Channel Multiplexing 11
1.2.3 Modulation Formats 13
1.3 Optical Communication Systems 16
1.4 Lightwave System Components 18
1.4.1 Optical Fibers as a Communication Channel 18
1.4.2 Optical Transmitters 18
1.4.3 Optical Receivers 19
Problems 20
References 21
2 Optical Fibers 24
2.1 Geometrical-Optics Description 24
2.1.1 Step-Index Fibers 25
2.1.2 Graded-Index Fibers 27
2.2 Wave Propagation 29
2.2.1 Maxwell’s Equations 29
2.2.2 Fiber Modes 31
2.2.3 Single-Mode Fibers 34
2.3 Dispersion in Single-Mode Fibers 37
2.3.1 Group-Velocity Dispersion 38
2.3.2 Material Dispersion 39
2.3.3 Waveguide Dispersion 40
2.3.4 Higher-Order Dispersion 41
2.3.5 Polarization-Mode Dispersion 43
2.4 Dispersion-Induced Limitations 44
2.4.1 Basic Propagation Equation 45
2.4.2 Chirped Gaussian Pulses 46
2.4.3 Limitations on the Bit Rate 49
2.5 Fiber Losses 52
2.5.1 Attenuation Coefficient 52
2.5.2 Material Absorption 53
2.5.3 Rayleigh Scattering 54
2.5.4 Waveguide Imperfections 55
2.6 Nonlinear Optical Effects 56
2.6.1 Stimulated Light Scattering 56
2.6.2 Nonlinear Phase Modulation 60
2.6.3 Four-Wave Mixing 63
2.7 Fiber Design and Fabrication 64
2.7.1 Silica Fibers 64
2.7.2 Plastic Optical Fibers 67
2.7.3 Cables and Connectors 69
Problems 70
References 72
3 Optical Transmitters 75
3.1 Semiconductor Laser Physics 75
3.1.1 Spontaneous and Stimulated Emissions 76
3.1.2 Nonradiative Recombination 77
3.1.3 Optical Gain 78
3.1.4 Feedback and Laser Threshold 80
3.1.5 Laser Structures and Modes 81
3.2 Single-Mode Semiconductor Lasers 83
3.2.1 Distributed Feedback Lasers 83
3.2.2 Coupled-Cavity Semiconductor Lasers 85
3.2.3 Tunable Semiconductor Lasers 86
3.2.4 Vertical-Cavity Surface-Emitting Lasers 88
3.3 Semiconductor Laser Characteristics 89
3.3.1 CW Characteristics 89
3.3.2 Modulation Bandwidth 92
3.3.3 Relative Intensity Noise 94
3.3.4 Spectral Linewidth 97
3.4 Modulation Techniques 98
3.4.1 Direct Modulation 99
3.4.2 External Modulation 100
3.5 Light-Emitting Diodes 103
3.5.1 LED Characteristics 104
3.5.2 LED Structures 106
3.6 Transmitter Design 108
3.6.1 Source–Fiber Coupling 108
3.6.2 Driving Circuitry 110
3.6.3 Reliability and Packaging 111
Problems 113
References 115
4 Optical Receivers 119
4.1 Basic Concepts 119
4.1.1 Responsivity and Quantum Efficiency 119
4.1.2 Rise Time and Bandwidth 121
4.2 Common Photodetectors 122
4.2.1 p–n Photodiodes 122
4.2.2 p–i–n Photodiodes 124
4.2.3 Avalanche Photodiodes 127
4.2.4 MSM Photodetectors 133
4.3 Receiver Design 135
4.3.1 The Front End 135
4.3.2 The Linear Channel 137
4.3.3 Data-Recovery Section 138
4.3.4 Integrated Receivers 139
4.4 Receiver Noise 141
4.4.1 Noise Mechanisms 141
4.4.2 SNR of p–i–n Receivers 143
4.4.3 SNR of APD Receivers 144
4.5 Coherent Detection 148
4.5.1 Local Oscillator 148
4.5.2 Homodyne Detection 149
4.5.3 Heterodyne Detection 150
4.5.4 Signal-to-Noise Ratio 150
4.6 Receiver Sensitivity 151
4.6.1 Bit-Error Rate 151
4.6.2 Minimum Received Power 154
4.6.3 Quantum Limit of Photodetection 156
4.7 Sensitivity Degradation 157
4.7.1 Extinction Ratio 157
4.7.2 Intensity Noise 158
4.7.3 Timing Jitter 160
4.8 Receiver Performance 162
Problems 164
References 166
5 Lightwave Systems 170
5.1 System Architectures 170
5.1.1 Point-to-Point Links 170
5.1.2 Distribution Networks 172
5.1.3 Local-Area Networks 173
5.2 Design Guidelines 175
5.2.1 Loss-Limited Lightwave Systems 175
5.2.2 Dispersion-Limited Lightwave Systems 176
5.2.3 Power Budget 177
5.2.4 Rise-Time Budget 179
5.3 Long-Haul Systems 181
5.3.1 Performance-Limiting Factors 181
5.3.2 Terrestrial Lightwave Systems 183
5.3.3 Undersea Lightwave Systems 186
5.4 Sources of Power Penalty 188
5.4.1 Modal Noise 188
5.4.2 Mode-Partition Noise 190
5.4.3 Reflection Feedback and Noise 191
5.4.4 Dispersive Pulse Broadening 194
5.4.5 Frequency Chirping 195
5.4.6 Eye-Closure Penalty 197
5.5 Forward Error Correction 198
5.5.1 Error-Correcting Codes 198
5.5.2 Coding Gain 199
5.6 Computer-Aided Design 200
Problems 202
References 204
6 Multichannel Systems 208
6.1 WDM Systems and Networks 208
6.1.1 High-Capacity Point-to-Point Links 209
6.1.2 Wide-Area and Metro-Area Networks 212
6.1.3 Multiple-Access WDM Networks 215
6.2 WDM Components 216
6.2.1 Optical Filters 217
6.2.2 Multiplexers and Demultiplexers 222
6.2.3 Add–Drop Multiplexers 224
6.2.4 Star Couplers 227
6.2.5 Wavelength Routers 228
6.2.6 WDM Transmitters and Receivers 230
6.3 System Performance Issues 233
6.3.1 Linear Crosstalk 233
6.3.2 Raman-Induced Nonlinear Crosstalk 235
6.3.3 XPM-Induced Nonlinear Crosstalk 237
6.3.4 FWM-Induced Nonlinear Crosstalk 239
6.3.5 Other Design Issues 240
6.4 Time-Division Multiplexing 241
6.4.1 Time-Domain Multiplexing 242
6.4.2 Time-Domain Demultiplexing 243
6.4.3 Performance of OTDM Systems 245
6.5 Subcarrier Multiplexing 246
6.5.1 Analog and Digital SCM Systems 246
6.5.2 Orthogonal Frequency-Division multiplexing 248
6.6 Code-Division Multiplexing 250
6.6.1 Time-Domain Encoding 251
6.6.2 Frequency-Domain Encoding 253
Problems 255
References 257
7 Loss Management 264
7.1 Compensation of Fiber Losses 264
7.1.1 Periodic Amplification Scheme 265
7.1.2 Lumped Versus Distributed Amplification 267
7.1.3 Bidirectional Pumping Scheme 268
7.2 Erbium-Doped Fiber Amplifiers 269
7.2.1 Pumping and Gain Spectrum 269
7.2.2 Two-Level Model 270
7.2.3 Amplifier Noise 273
7.2.4 Multichannel Amplification 275
7.3 Raman Amplifiers 277
7.3.1 Raman Gain and Bandwidth 278
7.3.2 Raman-Induced Signal Gain 279
7.3.3 Multiple-Pump Raman Amplification 281
7.3.4 Noise Figure of Raman Amplifiers 283
7.4 Optical Signal-To-Noise Ratio 285
7.4.1 Lumped Amplification 285
7.4.2 Distributed Amplification 287
7.5 Electrical Signal-To-Noise Ratio 288
7.5.1 ASE-Induced Current Fluctuations 288
7.5.2 Impact of ASE on SNR 290
7.5.3 Noise Buildup in an Amplifier Chain 291
7.6 Receiver Sensitivity and Q Factor 292
7.6.1 Bit-Error Rate 292
7.6.2 Relation between Q Factor and Optical SNR 294
7.7 Role of Dispersive and Nonlinear Effects 295
7.7.1 Noise Growth through Modulation Instability 295
7.7.2 Noise-Induced Signal Degradation 297
7.7.3 Noise-Induced Energy Fluctuations 299
7.7.4 Noise-Induced Timing Jitter 300
7.8 Periodically Amplified Lightwave Systems 300
7.8.1 Numerical Approach 301
7.8.2 Optimum Launched Power 304
Problems 306
References 307
8 Dispersion Management 310
8.1 Dispersion Problem and Its Solution 310
8.2 Dispersion-Compensating Fibers 312
8.2.1 Conditions for Dispersion Compensation 312
8.2.2 Dispersion Maps 313
8.2.3 DCF Designs 315
8.3 Fiber Bragg Gratings 317
8.3.1 Constant-Period Gratings 318
8.3.2 Chirped Fiber Gratings 320
8.3.3 Sampled Gratings 322
8.4 Dispersion-Equalizing Filters 325
8.4.1 Gires–Tournois Filters 325
8.4.2 Mach–Zehnder and Other Filters 327
8.5 Optical Phase Conjugation 329
8.5.1 Principle of Operation 330
8.5.2 Compensation of Self-Phase Modulation 331
8.5.3 Generation of Phase-Conjugated Signal 332
8.6 Advanced Techniques 335
8.6.1 Tunable Dispersion Compensation 335
8.6.2 Higher-Order Dispersion Management 338
8.6.3 PMD Compensation 340
8.7 Electronic Dispersion Compensation 343
8.7.1 Pre-compensation at the Transmitter 343
8.7.2 Post-Compensation at the Receiver 347
Problems 349
References 351
9 Control of Nonlinear Effects 355
9.1 Impact of Fiber Nonlinearity 355
9.1.1 System Design Issues 356
9.1.2 Semianalytic Approach 359
9.1.3 Soliton and Pseudo-linear Regimes 361
9.2 Solitons in Optical Fibers 363
9.2.1 Properties of Optical Solitons 364
9.2.2 Loss-Managed Solitons 367
9.2.3 Dispersion-Managed Solitons 370
9.2.4 Timing Jitter 374
9.3 Pseudo-linear Lightwave Systems 378
9.3.1 Origin of Intrachannel Nonlinear Effects 378
9.3.2 Intrachannel Cross-Phase Modulation 380
9.3.3 Intrachannel Four-Wave Mixing 384
9.4 Management of Nonlinear Effects 387
9.4.1 Optimization of Dispersion Maps 387
9.4.2 Phase-Alternation Technique 390
9.4.3 Polarization Bit Interleaving 392
9.4.4 Optical Phase Conjugation 393
9.4.5 Phase-Sensitive Amplification 395
Problems 396
References 398
10 Coherent Lightwave Systems 402
10.1 Coherent Transmitters 403
10.1.1 Encoding of Optical Signals 403
10.1.2 Amplitude and Phase Modulators 405
10.1.3 Quadrature modulator 406
10.2 Coherent Receivers 408
10.2.1 Synchronous Heterodyne Demodulation 408
10.2.2 Asynchronous Heterodyne Demodulation 410
10.2.3 Optical Delay Demodulation 411
10.2.4 Phase Diversity and Polarization Diversity 413
10.3 Noise and Bit-Error Rate 415
10.3.1 Synchronous Heterodyne Receivers 415
10.3.2 Asynchronous Heterodyne Receivers 418
10.3.3 Receivers with Optical Delay Demodulation 419
10.4 Sources of Performance Degradation 421
10.4.1 Intensity Noise of Lasers 421
10.4.2 Phase Noise of Lasers 422
10.4.3 Effects of Fiber’s Dispersion 424
10.5 Management of Nonlinear Effects 425
10.5.1 Nonlinear Phase Noise 426
10.5.2 Compensation of Nonlinear Phase Noise 429
10.5.3 Nonlinear Interference Noise 432
10.6 Digital Signal Processing 435
10.6.1 Removal of Intermediate Frequency and Phase fluctuations 435
10.6.2 Compensation of GVD and PMD 437
10.6.3 Digital Backward Propagation 440
10.7 Experimental Progress 442
10.7.1 DPSK and DQPSK formats 442
10.7.2 QPSK and QAM formats 445
10.7.3 Coherent Orthogonal FDM 448
10.7.4 Optical Superchannels 450
10.8 Channel Capacity 452
Problems 454
References 455
11 Space-Division Multiplexing 462
11.1 SDM Technique 462
11.2 Modes of Optical Fibers 464
11.2.1 Step-Index Fibers 464
11.2.2 Graded-Index Fibers 467
11.2.3 Multicore Fibers 469
11.3 SDM Components 471
11.3.1 Design of SDM Fibers 471
11.3.2 Spatial Multiplexers and Demultiplexers 474
11.3.3 Multicore/Multimode Fiber Amplifiers 479
11.3.4 Other SDM Components 481
11.4 Modeling of SDM Systems 482
11.4.1 Multimode Coupled Nonlinear Equations 483
11.4.2 Averaged Multimode Nonlinear Equations 486
11.4.3 Nonlinear Effects in MCFs 488
11.4.4 Nonlinear Effects in MMFs 491
11.5 Experimental Progress 494
11.5.1 MCF-Based SDM Systems 494
11.5.2 MMF-Based SDM Systems 496
11.5.3 High-Capacity SDM Systems 498
Problems 499
References 500
12 Advanced Topics 505
12.1 Optical Signal Processing 506
12.1.1 Nonlinear Optical Loop Mirrors 506
12.1.2 Parametric Amplifiers 510
12.1.3 Semiconductor Optical Amplifiers 513
12.1.4 Bistable Optical Devices 516
12.1.5 Optical Flip–Flops 518
12.2 Wavelength Conversion 522
12.2.1 XPM-Based Wavelength Converters 522
12.2.2 FWM-Based Wavelength Converters 525
12.2.3 Semiconductor Waveguides 528
12.2.4 SOA-Based Wavelength Converters 530
12.3 Ultrafast Optical Switching 532
12.3.1 Time-Domain Demultiplexing 532
12.3.2 Packet Switching 536
12.3.3 Format Conversion 538
12.4 Optical Regeneration 540
12.4.1 2R Regenerators 541
12.4.2 3R Regenerators 545
12.4.3 Regeneration of Phase-Encoded Signals 549
12.5 Nonlinear Frequency-Division Multiplexing 552
12.5.1 Nonlinear Fourier Transform 552
12.5.2 Practical Implementation 554
Problems 556
References 557
A System of Units 566
B Acronyms 568
C Formula for Pulse Broadening 572
D Nyquist Pulses 574
References 575
Index 576
