Preface ...................................................... xvii
Author ........................................................ xxi
List of Abbreviations and Notations ......................... xxiii
1 Introduction ................................................. 1
1.1 Historical Perspectives ................................. 1
1.2 Digital Modulation for Advanced Optical Transmission
Systems ................................................. 4
1.3 Demodulation Techniques ................................. 7
1.4 MATLAB® and Simulink® Platforms ......................... 8
1.5 Organization of the Chapters in This Book ............... 8
2 Optical Waveguides: Geometrical and Lightwave-Guiding
Properties .................................................. 11
2.1 Introduction ........................................... 11
2.2 Dielectric Slab Optical Waveguides ..................... 12
2.2.1 Structure ....................................... 13
2.2.2 Numerical Aperture .............................. 13
2.2.3 Modes of the Symmetric Dielectric Slab
Waveguides ...................................... 14
2.2.3.1 Wave Equations ......................... 15
2.2.4 Optical Guided Modes ............................ 16
2.2.4.1 Even ТЕ Modes .......................... 17
2.2.4.2 Odd ТЕ Modes ........................... 17
2.2.4.3 Graphical Solutions for Guided ТЕ
Modes (Even and Odd) ................... 18
2.2.5 Cutoff Properties ............................... 18
2.3 Optical Fiber: General Properties ...................... 19
2.3.1 Geometrical Structures and Index Profiles ....... 19
2.3.1.1 Step-Index Profile ..................... 19
2.3.1.2 Graded-Index Profile ................... 20
2.3.1.3 Power Law-Index Profile ................ 21
2.3.1.4 Gaussian-Index Profile ................. 21
2.3.2 Fundamental Mode of Weakly Guiding Fibers ....... 21
2.3.2.1 Solutions of the Wave Equation for
Step-Index Fiber ....................... 22
2.3.3 Cutoff Properties ............................... 26
2.4 Power Distribution ..................................... 27
2.4.1 Approximation of Spot Size r0 of a Step-Index
Fiber ........................................... 29
2.4.2 Equivalent Step-Index Description ............... 29
2.4.2.1 Definitions of ESI Parameters .......... 30
2.4.2.2 Accuracy and Limits .................... 31
2.4.2.3 Examples on ESI Techniques ............. 31
2.4.2.4 General Method ......................... 32
2.5 Nonlinear Optical Effects .............................. 33
2.5.1 Nonlinear Phase Modulation Effects .............. 33
2.5.1.1 Self-Phase Modulation .................. 33
2.5.1.2 Cross-Phase Modulation ................. 34
2.5.2 Stimulated Scattering Effects ................... 35
2.5.2.1 Stimulated Brillouin Scattering ........ 36
2.5.2.2 Stimulated Raman Scattering ............ 37
2.5.3 Four-Wave Mixing ................................ 38
2.6 Optical Fiber Manufacturing and Cabling ................ 39
2.7 Concluding Remarks ..................................... 40
2.8 Problems ............................................... 42
Appendix: Technical Data of Single-Mode Optical Fibers ...... 44
References .................................................. 57
3 Optical Fibers: Signal Attenuation and Dispersion ........... 59
3.1 Introduction ........................................... 59
3.2 Signal Attenuation in Optical Fibers ................... 60
3.2.1 Intrinsic or Material Attenuation ............... 60
3.2.2 Absorption ...................................... 61
3.2.3 Rayleigh Scattering ............................. 61
3.2.4 Waveguide Loss .................................. 61
3.2.5 Bending Loss .................................... 61
3.2.6 Microbending Loss ............................... 61
3.2.7 Joint or Splice Loss ............................ 62
3.2.8 Attenuation Coefficient ......................... 63
3.3 Signal Distortion in Optical Fibers .................... 63
3.3.1 Basics on Group Velocity ........................ 63
3.3.2 Group Velocity Dispersion ....................... 65
3.3.2.1 Material Dispersion .................... 65
3.3.2.2 Waveguide Dispersion ................... 67
3.4 Transfer Function of Single-Mode Fibers ................ 70
3.4.1 Higher-Order Dispersion ......................... 70
3.4.2 Transmission Bit Rate and Dispersion Factor ..... 72
3.4.3 Polarization Mode Dispersion .................... 73
3.4.4 Fiber Nonlinearity .............................. 76
3.5 Advanced Optical Fibers: Dispersion Shifted,
Dispersion Flattened, and Dispersion Compensated ....... 78
3.6 Effects of Mode Hopping ................................ 79
3.7 Numerical Solution: Split-Step Fourier Method .......... 80
3.7.1 Symmetrical Split-Step Fourier Method ........... 80
3.7.2 MATLAB® Program and MATLAB® and Simulink®
Models of SSFM .................................. 81
3.7.2.1 MATLAB® Program ........................ 81
3.7.2.2 MATLAB® and Simulink® Models ........... 84
3.7.3 Modeling of Polarization Mode Dispersion ........ 84
3.7.4 Optimization of Symmetrical SSFM ................ 85
3.7.4.1 Optimization of Computational Time ..... 85
3.7.4.2 Mitigation of Windowing Effect and
Waveform Discontinuity ................. 86
3.8 Concluding Remarks ..................................... 87
3.9 Problems ............................................... 87
Appendix 3.A.1: MATLAB® Program of the Design of Optical
Fibers—A Solution to the Mini-Project Design ........... 91
Appendix 3.A.2: Program Listings of the Design of Standard
Single-Mode Fibers ..................................... 92
Appendix 3.A.3: Program Listings of the Design of Nonzero
Dispersion-Shifted Fibers .............................. 94
Appendix 3.A.4: Program Listings of the Split-Step Fourier
Method with SPM and Raman Gain Distribution ............ 96
Appendix 3.A.5: Program Listings of the Initialization
File ................................................... 98
References ................................................. 100
4 Overview of Modeling Techniques for Optical Transmission
Systems Using MATLAB® and Simulink® ........................ 103
4.1 Overview .............................................. 103
4.2 Optical Transmitter ................................... 105
4.2.1 Background of External Optical Modulators ...... 106
4.2.2 Optical Phase Modulator ........................ 106
4.2.3 Optical Intensity Modulator .................... 107
4.2.3.1 Single-Drive MZIM ..................... 107
4.2.3.2 Dual-Drive MZIM ....................... 108
4.3 Impairments of Optical Fiber .......................... 109
4.3.1 Chromatic Dispersion ........................... 109
4.3.2 Chromatic Dispersion as a Total of Material
Dispersion and Waveguide Dispersion ............ 110
4.3.3 Dispersion Length .............................. 112
4.3.4 Polarization Mode Dispersion ................... 113
4.3.5 Fiber Nonlinearity ............................. 114
4.4 Modeling of Fiber Propagation ......................... 115
4.4.1 Symmetrical Split-Step Fourier Method .......... 115
4.4.2 Modeling of Polarization Mode Dispersion ....... 117
4.4.3 Optimization of Symmetrical SSFM ............... 118
4.4.3.1 Optimization of Computational Time .... 118
4.4.3.2 Mitigation of Windowing Effect and
Waveform Discontinuity ................ 118
4.5 Optical Amplifiers .................................... 118
4.5.1 ASE Noise ...................................... 118
4.5.2 Noise Figure ................................... 119
4.5.3 Optical and Electrical Filters ................. 119
4.6 Optical Receiver ...................................... 120
4.7 Performance Evaluation ................................ 122
4.7.1 Optical Signal-to-Noise Ratio .................. 123
4.7.2 OSNR Penalty ................................... 123
4.7.3 Eye Opening .................................... 123
4.7.4 Conventional Evaluation Methods ................ 124
4.7.4.1 Monte Carlo Method .................... 124
4.7.4.2 Single Gaussian Statistical Method .... 125
4.7.5 Novel Statistical Methods ...................... 126
4.7.5.1 Multiple Gaussian Distributions
Method ................................ 126
4.7.5.2 Generalized Pareto Distribution
Method ................................ 128
4.8 MATLAB® and Simulink® Modeling Platforms .............. 130
4.9 Concluding Remarks .................................... 137
References ................................................. 138
5 Optical Modulation ......................................... 141
5.1 Introduction .......................................... 141
5.2 Direct Modulation ..................................... 142
5.2.1 General Introduction ........................... 142
5.2.2 Physics of Semiconductor Lasers ................ 143
5.2.2.1 The Semiconductor p-n Junction for
Lasing Lightwaves ..................... 143
5.2.2.2 Optical Gain Spectrum ................. 144
5.2.2.3 Types of Semiconductor Lasers ......... 145
5.2.2.4 Fabry-Perot Heterojunction
Semiconductor Laser ................... 145
5.2.2.5 Distributed-Feedback Semiconductor
Laser ................................. 146
5.2.2.6 Constricted Mesa Semiconductor
Laser ................................. 147
5.2.2.7 Special Semiconductor Laser Source .... 148
5.2.2.8 Single-Mode Optical Laser Rate
Equations ............................. 148
5.2.2.9 Dynamic Response of Laser Source ...... 150
5.2.2.10 Frequency Chirp ....................... 151
5.2.2.11 Laser Noises .......................... 152
5.3 External Modulation Using Optical Modulators .......... 156
5.3.1 Phase Modulators ............................... 157
5.3.2 Intensity Modulators ........................... 157
5.3.3 Phasor Representation and Transfer
Characteristics ................................ 158
5.4 Bias Control .......................................... 160
5.4.1 Chirp-Free Optical Modulators .................. 160
5.4.1.1 Structures of Photonic Modulators ..... 161
5.4.2 Typical Operational Parameters of Optical
Intensity Modulators ........................... 163
5.4.3 MATLAB® and Simulink® Models of External
Optical Modulators ............................. 163
5.4.3.1 Phase Modulation Model and Intensity
Modulation ............................ 163
5.4.3.2 Dense Wavelength Division
Multiplexing Optical Multiplexers
and Modulators ........................ 164
5.5 Concluding Remarks .................................... 167
Appendix: MATLAB® Program for Solving the Laser Rate
Equation .............................................. 167
References ................................................. 169
6 Optical Transmitters for Advanced Modulation Format ........ 171
6.1 Introduction .......................................... 171
6.2 External Modulation and Advanced Modulation Formats ... 172
6.2.1 Modulation Formats and Pulse Shaping ........... 177
6.2.1.1 Generation ............................ 177
6.2.1.2 Phasor Representation ................. 179
6.2.1.3 Phasor Representation of CSRZ
Pulses ................................ 180
6.2.1.4 Phasor Representation of RZ33
Pulses ................................ 181
6.2.2 Differential Phase Shift Keying ................ 182
6.2.2.1 Background ............................ 182
6.2.2.2 Optical DPSK Transmitter .............. 183
6.3 Generation of Modulation Formats ...................... 184
6.3.1 Introductory Remarks ........................... 184
6.3.2 Amplitude-Modulation ASK-NRZ and ASK-RZ ........ 185
6.3.2.1 ASK-NRZ and ASK-RZ Pulse Shaping ...... 185
6.3.2.2 Amplitude-Modulation Carrier-
Suppressed RZ Formats ................. 187
6.3.3 Discrete Phase-Modulation NRZ Formats .......... 187
6.3.3.1 Differential Phase Shift Keying ....... 187
6.3.3.2 Differential Quadrature Phase Shift
Keying ................................ 188
6.3.3.3 NRZ-DPSK .............................. 188
6.3.3.4 RZ-DPSK ............................... 188
6.3.3.5 Generation of M-Ary Amplitude
Differential Phase Shift Keying
Using One MZIM ........................ 189
6.3.3.6 Continuous Phase Modulation PM-NRZ
Formats ............................... 191
6.3.3.7 Linear and Nonlinear MSK .............. 192
6.3.4 Photonic MSK Transmitter Using Two Cascaded
Electro-Optic Phase Modulators ................. 195
6.3.4.1 Configuration of Optical MSK
Transmitter Using Mach-Zehnder
Intensity Modulators: I-Q Approach .... 197
6.3.4.2 Single Sideband Optical Modulators .... 198
6.3.4.3 Optical RZ-MSK ........................ 198
6.3.5 Multi-Carrier Multiplexing Optical
Modulators ..................................... 199
6.3.6 Spectra of Modulation Formats .................. 202
6.4 Concluding Remarks .................................... 208
6.5 Problems .............................................. 209
Appendix: Structures of Mach-Zehnder Modulator ............. 214
References ................................................. 215
7 Direct Detection Optical Receivers ......................... 219
7.1 Introduction .......................................... 219
7.2 Optical Receivers in Various Systems .................. 220
7.3 Receiver Components ................................... 220
7.3.1 Structure ...................................... 220
7.3.2 Photodiodes .................................... 222
7.3.2.1 p-i-n Photodiodes ..................... 222
7.3.2.2 Avalanche Photodiodes ................. 222
7.3.2.3 Quantum Efficiency and Responsivity ... 223
7.3.2.4 High-Speed Photodetectors ............. 224
7.4 Detection and Noises .................................. 224
7.4.1 Linear Channel ................................. 225
7.4.2 Data Recovery .................................. 225
7.4.3 Noises in Photodetectors ....................... 225
7.4.4 Receiver Noises ................................ 226
7.4.4.1 Shot Noises ........................... 227
7.4.4.2 Quantum Shot Noise .................... 228
7.4.4.3 Thermal Noise ......................... 228
7.4.5 Noise Calculations ............................. 228
7.5 Performance Calculations for Binary Digital Optical
Systems ............................................... 229
7.5.1 Signals Received ............................... 230
7.5.2 Probability Distribution ....................... 231
7.5.3 Minimum Average Optical Received Power ......... 233
7.5.3.1 Fundamental Limit: Direct Detection ... 235
7.5.3.2 Equalized Signal Output ............... 235
7.5.3.3 Photodiode Shot Noise ................. 236
7.5.4 Total Output Noises and Pulse Shape
Parameters ..................................... 238
7.5.4.1 FET Front-End Optical Receiver ........ 239
7.5.4.2 BJT Front-End Optical Receiver ........ 240
7.6 HEMT-Matched Noise Network Preamplifier ............... 243
7.6.1 Structure ...................................... 243
7.6.2 Noise Theory and Equivalent Input Noise
Current ........................................ 246
7.7 Concluding Remarks .................................... 249
7.8 Problems .............................................. 249
Appendix: Noise Equations .................................. 251
References ................................................. 253
8 Optical Coherent Detection ................................. 255
8.1 Introduction .......................................... 255
8.2 Coherent Receiver Components .......................... 256
8.3 Coherent Detection .................................... 258
8.3.1 Optical Heterodyne Detection ................... 260
8.3.1.1 ASK Coherent System ................... 262
8.3.1.2 PSK Coherent System ................... 264
8.3.1.3 FSK Coherent System ................... 266
8.3.2 Optical Homodyne Detection ..................... 266
8.3.2.1 Detection and Optical PLL ............. 267
8.3.2.2 Quantum Limit Detection ............... 269
8.3.2.3 Linewidth Influences .................. 269
8.4 Self-Coherent Detection and Electronic DSP ............ 274
8.5 Digital Signal Processing Coherent Optical Receiver ... 275
8.5.1 Theory of DSP-Assisted Coherent Detection ...... 275
8.5.2 DSP-Based Phase Estimation and Correction of
Phase Noise and Nonlinear Effects .............. 280
8.5.3 DSP-Based Forward Phase Estimation Optical
Coherent Receivers of QPSK Modulation Format ... 281
8.6 Coherent Receiver Analysis ............................ 282
8.6.1 Shot Noise-Limited Receiver Sensitivity ........ 286
8.6.2 Receiver Sensitivity under Nonideal
Conditions ..................................... 286
8.7 MATLAB® and Simulink® Models .......................... 287
8.7.1 Phase Detection ................................ 287
8.7.2 Mach Zehnder Delay Interferometer .............. 287
8.7.3 Receiver with Coupler .......................... 290
8.7.4 π/2 Optical Hybrid Coupler ..................... 290
8.7.5 Amplitude Detection ............................ 293
8.7.6 Phase Detection ................................ 293
8.7.7 Electronic Noise Model of Electronic
Preamplifier ................................... 293
8.8 Concluding Remarks .................................... 293
8.9 Problems .............................................. 294
Appendix: π/2 Hybrid Coupler Embedded MATLAB® Code ......... 295
References ................................................. 295
9 Erbium-Doped Fiber Optical Amplifiers and Simulink®
Models ..................................................... 299
9.1 Introduction .......................................... 299
9.2 Fundamental and Theoretical Issues of EDFAs ........... 300
9.2.1 EDFA Configuration ............................. 300
9.2.2 EDFA Operational Principles .................... 302
9.2.2.1 Pump Wavelength and Absorption
Spectrum .............................. 302
9.2.2.2 Pump Mechanism ........................ 303
9.2.3 General Amplifier Noises and Gain in
Transmission ................................... 305
9.2.3.1 Amplifier Gain Modulation ............. 306
9.2.3.2 EDFAs in Long-Haul Transmission
Systems ............................... 306
9.3 EDFA Simulation Model ................................. 307
9.3.1 Amplifier Parameters ........................... 307
9.3.2 EDFAs Dynamic Model ............................ 309
9.3.3 EDFAs Steady-State Modeling Principles ......... 311
9.3.4 Population Inversion Factor .................... 311
9.3.5 Amplifier Noises ............................... 312
9.3.5.1 ASE Noise Model ....................... 312
9.3.5.2 Other Noise Sources ................... 312
9.3.6 Simulation Model ............................... 313
9.3.6.1 Simulator Design Outline .............. 313
9.3.6.2 Simulator Design Process .............. 314
9.3.6.3 Simulator Requirement ................. 314
9.3.6.4 Simulator Design Assumptions .......... 315
9.3.6.5 Further Assumptions ................... 316
9.3.7 EDFA Simulator ................................. 317
9.3.7.1 Using the EDFA Simulator .............. 318
9.3.7.2 Signal Data Stream Modeling ........... 318
9.3.7.3 Pump Source ........................... 318
9.3.7.4 Pumping Wavelength .................... 321
9.3.7.5 Pump Modulation ....................... 322
9.3.7.6 EDF Modeling .......................... 322
9.3.7.7 EDFA's Dynamic Gain Model ............. 323
9.3.7.8 EDFA's Steady-State Gain Model ........ 323
9.3.7.9 Population Inversion Factor
Modeling .............................. 324
9.3.7.10 Amplifier Noise Modeling .............. 325
9.3.7.11 Simulink® EDFA Simulator: Execution
Procedures ............................ 327
9.3.7.12 Amplification in the L Band ........... 330
9.3.8 Multichannel Operation of the EDFA ............. 333
9.3.8.1 ASE Measurement ....................... 334
9.3.8.2 Pump Wavelength Testing ............... 334
9.3.8.3 Gain Pump Modulation Effect ........... 335
9.3.8.4 Samples of the Simulink® Simulator .... 336
9.4 Concluding Remarks .................................... 337
References ................................................. 337
10 MATLAB® and Simulink® Modeling of Raman Amplification and
Integration in Fiber Transmission Systems .................. 339
10.1 Introduction .......................................... 339
10.2 ROA versus Erbium-Doped Fiber Amplifiers .............. 341
10.3 Raman Amplification ................................... 342
10.3.1 Principles ..................................... 342
10.3.2 Raman Amplification Coupled Equations .......... 343
10.3.3 Raman and Fiber Propagation under Linear and
Nonlinear Fiber Dispersion ..................... 345
10.3.3.1 Propagation Equation .................. 345
10.3.3.2 Standard Single-Mode Fiber and DCF
as Raman Fibers ....................... 346
10.3.3.3 Noise Figure .......................... 350
10.3.3.4 Dispersion ............................ 353
10.4 Nonlinear Raman Gain/Scattering Schrödinger
Equation .............................................. 353
10.4.1 Fiber Nonlinearities ........................... 354
10.4.2 Dispersion ..................................... 355
10.4.3 Split-Step Fourier Method ...................... 355
10.4.4 Gaussian Pulses, Eye Diagrams, and Bit Error
Rate ........................................... 356
10.5 Raman Amplification and Gaussian Pulse Propagation .... 356
10.5.1 Fiber Profiles ................................. 356
10.5.2 Gaussian Pulse Propagation ..................... 358
10.5.2.1 Bidirectional Pumping Case ............ 358
10.5.2.2 Forward-Pumping Case .................. 359
10.5.2.3 Backward-Pumping Case ................. 360
10.5.2.4 Back-to-Back Performance .............. 360
10.5.2.5 Propagation under No Amplification .... 361
10.5.2.6 Propagation under Fiber Raman
Amplification ......................... 361
10.6 Optically Amplified Transmission ...................... 362
10.6.1 EDFA Amplification and Distributed Raman
Amplification over 99 km Fiber (1km
Mismatch) ...................................... 362
10.6.1.1 EDFA .................................. 362
10.6.1.2 Distributed Raman Amplification ....... 362
10.6.2 Hybrid Amplification ........................... 364
10.6.3 Long-Haul Optically Amplified Transmission ..... 366
10.6.3.1 Eye Diagram and BER Evaluation under
Noise Loading Effects ................. 366
10.6.3.2 Launched Power versus BER ............. 367
10.6.3.3 Dispersion Tolerance .................. 372
10.6.3.4 Remarks ............................... 374
10.7 Concluding Remarks .................................... 375
10.8 Problems .............................................. 376
Appendix: Raman Amplification and Split-Step Fourier
Method—MATLAB® Program ................................ 377
References ................................................. 379
11 Design of Optical Communication Systems and Simulink®
Models ..................................................... 381
11.1 Introduction .......................................... 381
11.2 Long-Haul Optical Transmission Systems ................ 383
11.2.1 Intensity-Modulation Direct-Detection
Systems ........................................ 383
11.2.2 Loss-Limited Optical Communication Systems ..... 385
11.2.3 Dispersion-Limited Optical Communication
Systems ........................................ 385
11.2.4 System Preliminary Design ...................... 386
11.2.4.1 Single-Span Optical Transmission
Systems ............................... 386
11.2.4.2 Power Budget .......................... 386
11.2.4.3 Rise-Time/Dispersion Budget ........... 387
11.2.4.4 Multi-Span Optical Transmission
Systems ............................... 389
11.2.4.5 Maximum Transmission Distance of
Cascaded Optically Amplified Multi-
Span Systems .......................... 390
11.2.5 Gaussian Approximation ......................... 392
11.2.5.1 Link Budget Measurement ............... 393
11.2.5.2 System Margin Measurement ............. 394
11.2.6 Some Notes on the Design of Optical
Transmission Systems ........................... 397
11.2.6.1 Allocations of Wavelength Channels .... 397
11.2.6.2 Multiwavelength MATLAB® and
Simulink® Models ...................... 400
11.2.6.3 Link Design Process ................... 400
11.2.6.4 Link Budget Considerations ............ 402
11.3 Link Budget Calculations under Linear and Nonlinear
Effects ............................................... 403
11.3.1 Budget ......................................... 404
11.3.2 System Impairments ............................. 404
11.3.2.1 Power and Time Eyes ................... 405
11.3.2.2 Dispersion Tolerance due to
Wavelength Channels and Nonlinear
Effects ............................... 406
11.3.2.3 Dependence on Wavelength Channels
and Launched Power .................... 406
11.3.2.4 Budget ................................ 406
11.3.3 Engineering an OADM Transmission Link .......... 409
11.4 Problems .............................................. 410
12 Simulink® Models of Optically Amplified Digital
Transmission Systems ....................................... 415
12.1 ASK Modulation Formats Transmission Models ............ 415
12.1.1 Introductory Remarks ........................... 416
12.1.2 Components for Advanced Optical Communication
System ......................................... 417
12.1.2.1 Optical Source ........................ 418
12.1.2.2 Optical Modulators .................... 419
12.1.2.3 Mach-Zehnder Intensity Modulator ...... 419
12.1.3 Transmission Loss and Dispersion Revisited ..... 421
12.1.4 Nonlinear Effects .............................. 422
12.1.5 Signal Propagation Model ....................... 422
12.1.5.1 Nonlinear Schrödinger Propagation
Equation .............................. 422
12.1.6 Low-Pass Equivalent Model: Linear Operating
Region ......................................... 423
12.1.7 Modulation Formats ............................. 423
12.1.8 NRZ or NRZ-ASK ................................. 424
12.1.9 RZ or RZ-ASK ................................... 424
12.2 Return-to-Zero Optical Pulses ......................... 427
12.2.1 Generation ..................................... 427
12.2.2 Phasor Representation .......................... 430
12.2.3 Phasor Representation of CSRZ Pulses ........... 430
12.2.4 Phasor Representation of RZ33 Pulses ........... 432
12.3 Differential Phase Shift Keying ....................... 433
12.3.1 NRZ-DPSK ....................................... 434
12.3.2 RZ-DPSK ........................................ 434
12.3.3 Receiver ....................................... 435
12.4 Simulink® Models ...................................... 436
12.4.1 Bernoulli Binary Generator ..................... 437
12.4.2 DFB Laser ...................................... 438
12.4.3 Mach-Zehnder Interferometric Modulator ......... 438
12.4.3.1 Pulse Carver .......................... 439
12.4.3.2 Data Modulator ........................ 442
12.4.3.3 Differential Data Encoder ............. 443
12.4.4 Back-to-Back Receiver .......................... 443
12.4.4.1 Eye Diagram ........................... 446
12.4.5 Signal Propagation ............................. 446
12.4.6 Bit Error Rate ................................. 447
12.5 DQPSK Modulation Formats Transmission Models .......... 449
12.5.1 DQPSK Optical System Components ................ 450
12.5.1.1 DQPSK Transmitter ..................... 450
12.5.1.2 DQPSK Receiver ........................ 451
12.5.2 MATLAB® and Simulink® Simulators ............... 454
12.6 Spectral Characteristics of Advanced Modulation
Formats ............................................... 454
12.7 Partial Responses Duo-Binary Transmission Model ....... 459
12.7.1 Remarks ........................................ 459
12.7.2 The DBM Formatter .............................. 460
12.7.3 40Gb/s DB Optical Fiber Transmission Systems ... 461
12.7.4 Electro-Optic Duo-Binary Transmitter ........... 463
12.7.4.1 The Duo-Binary Encoder ................ 463
12.7.4.2 The External Modulator ................ 465
12.7.4.3 Duo-Binary Transmitters and
Precoder .............................. 466
12.7.4.4 Alternative Phase DB Transmitter ...... 468
12.8 MSK Transmission Model ................................ 470
12.8.1 Introduction ................................... 470
12.8.2 Generation of Optical MSK-Modulated Signals .... 473
12.8.2.1 Optical MSK Transmitter Using Two
Cascaded Electro-Optic Phase
Modulators ............................ 473
12.8.2.2 Possibility to Generate Optical
M-Ary CPFSK Format .................... 474
12.8.2.3 Detection of M-Ary CPFSK Modulated
Optical Signal ........................ 474
12.8.2.4 Optical MSK Transmitter Using
Parallel Mach-Zehnder Intensity
Modulators (I-Q Approach) ............. 475
12.8.3 Optical Binary-Amplitude MSK Format ............ 480
12.8.3.1 Generation ............................ 480
12.8.3.2 Detection ............................. 484
12.8.4 Typical Simulation Results ..................... 484
12.8.4.1 Transmission Performance of Linear
and Nonlinear Optical MSK Systems ..... 484
12.9 Star-QAM Transmission Systems for lOOGb/s Capacity .... 488
12.9.1 Introductory Remarks ........................... 489
12.9.2 Design of 16-QAM Signal Constellation .......... 490
12.9.2.1 Star 16-QAM ........................... 490
12.9.2.2 8-DPSK_2-ASK 16-Star-QAM .............. 492
12.9.2.3 Receiver Sensitivity and Dispersion
Tolerance ............................. 495
12.9.2.4 Long-Haul Transmission ................ 496
12.10 Concluding Remarks ................................... 499
Appendix 12.A: Simulink® and Simulation Guidelines ............ 500
12.A.1 MATLAB® and Simulink® ............................... 500
12.A.2 Guidelines for Using Simulink® Models ............... 501
12.A.3 MATLAB® Files ....................................... 505
12.A.3.1 Initialization File ........................ 505
References ................................................. 512
Appendix: A Short Glossary of Terms in Optical Fiber
Communications ............................................. 515
Index ......................................................... 521
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