Enabling Technologies for High Spectral-efficiency Coherent Optical Communication Networks

List of Contributors xv Preface xvii 1 Introduction 1 Xiang Zhou and Chongjin Xie 1.1 High-Capacity Fiber Transmission Technology Evolution 1 1.2 Fundamentals of Coherent Transmission Technology 4 1.3 Outline of this Book 8 References 9 2 Multidimensional Optimized Optical Modulation Formats 13 Magnus Karlsson and Erik Agrell 2.1 Introduction 13 2.2 Fundamentals of Digital Modulation 15 2.3 Modulation Formats and Their Ideal Performance 20 2.4 Combinations of Coding and Modulation 31 2.5 Experimental Work 40 2.6 Summary and Conclusions 54 References 56 3 Advances in Detection and Error Correction for Coherent Optical Communications: Regular, Irregular, and Spatially Coupled LDPC Code Designs 65 Laurent Schmalen, Stephan ten Brink, and Andreas Leven 3.1 Introduction 65 3.2 Differential Coding for Optical Communications 67 3.3 LDPC-Coded Differential Modulation 83 3.4 Coded Differential Modulation with Spatially Coupled LDPC Codes 101 3.5 Conclusions 112 Appendix: LDPC-Coded Differential Modulation--Decoding Algorithms 112 Differential Decoding 114 LDPC Decoding 115 References 117 4 Spectrally Efficient Multiplexing: Nyquist-WDM 123 Gabriella Bosco 4.1 Introduction 123 4.2 Nyquist Signaling Schemes 125 4.3 Detection of a Nyquist-WDM Signal 134 4.4 Practical Nyquist-WDM Transmitter Implementations 137 4.5 Nyquist-WDM Transmission 146 4.6 Conclusions 149 References 150 5 Spectrally Efficient Multiplexing - OFDM 157 An Li, Di Che, Qian Hu, Xi Chen, and William Shieh 5.1 OFDM Basics 158 5.2 Coherent Optical OFDM (CO-OFDM) 161 5.3 Direct-Detection Optical OFDM (DDO-OFDM) 169 5.4 Self-Coherent Optical OFDM 174 5.5 Discrete Fourier Transform Spread OFDM System (DFT-S OFDM) 180 5.6 OFDM-Based Superchannel Transmissions 183 5.7 Summary 193 References 194 6 Polarization and Nonlinear Impairments in Fiber Communication Systems 201 Chongjin Xie 6.1 Introduction 201 6.2 Polarization of Light 202 6.3 PMD and PDL in Optical Communication Systems 206 6.4 Modeling of Nonlinear Effects in Optical Fibers 209 6.5 Coherent Optical Communication Systems and Signal Equalization 211 6.6 PMD and PDL Impairments in Coherent Systems 215 6.7 Nonlinear Impairments in Coherent Systems 228 6.8 Summary 240 References 241 7 Analytical Modeling of the Impact of Fiber Non-Linear Propagation on Coherent Systems and Networks 247 Pierluigi Poggiolini, Yanchao Jiang, Andrea Carena, and Fabrizio Forghieri 7.1 Why are Analytical Models Important? 247 7.2 Background 248 7.3 Introducing the GN-EGN Model Class 260 7.4 Model Selection Guide 269 7.5 Conclusion 294 Acknowledgements 295 Appendix 295 A.1 The White-Noise Approximation 295 A.1.2 The Link Function my 296 A.1.3 The EGN Model Formulas for the X2-X4 and M1-M3 Islands 297 A.1.4 Outline of GN-EGN Model Derivation 299 A.1.5 List of Acronyms 303 References 304 8 Digital Equalization in Coherent Optical Transmission Systems 311 Seb Savory 8.1 Introduction 311 8.2 Primer on the Mathematics of Least Squares Finite Impulse Response Filters 312 8.3 Equalization of Chromatic Dispersion 318 8.4 Equalization of Polarization-Mode Dispersion 323 8.5 Concluding Remarks and Future Research Directions 329 Acknowledgments 330 References 330 9 Nonlinear Compensation for Digital Coherent Transmission 333 Guifang Li 9.1 Introduction 333 9.2 Digital Backward Propagation (DBP) 334 9.3 Reducing DBP Complexity for Dispersion-Unmanaged WDM Transmission 339 9.4 DBP for Dispersion-Managed WDM Transmission 342 9.5 DBP for Polarization-Multiplexed Transmission 349 9.6 Future Research 350 References 351 10 Timing Synchronization in Coherent Optical Transmission Systems 355 Han Sun and Kuang-Tsan Wu 10.1 Introduction 355 10.2 Overall System Environment 357 10.3 Jitter Penalty and Jitter Sources in a Coherent System 359 10.4 Digital Phase Detectors 368 10.5 The Chromatic Dispersion Problem 383 10.6 The Polarization-Mode Dispersion Problem 386 10.7 Timing Synchronization for Coherent Optical OFDM 390 10.8 Future Research 391 References 392 11 Carrier Recovery in Coherent Optical Communication Systems 395 Xiang Zhou 11.1 Introduction 395 11.2 Optimal Carrier Recovery 397 11.3 Hardware-Efficient Phase Recovery Algorithms 399 11.4 Hardware-Efficient Frequency Recovery Algorithms 416 11.5 Equalizer-Phase Noise Interaction and its Mitigation 424 11.6 Carrier Recovery in Coherent OFDM Systems 429 11.7 Conclusions and Future Research Directions 430 References 431 12 Real-Time Implementation of High-Speed Digital Coherent Transceivers 435 Timo Pfau 12.1 Algorithm Constraints 435 12.2 Hardware Implementation of Digital Coherent Receivers 442 References 446 13 Photonic Integration 447 Po Dong and Sethumadhavan Chandrasekhar 13.1 Introduction 447 13.2 Overview of Photonic Integration Technologies 449 13.3 Transmitters 451 13.4 Receivers 459 13.5 Conclusions 467 Acknowledgments 467 References 467 14 Optical Performance Monitoring for Fiber-Optic Communication Networks 473 Faisal N. Khan, Zhenhua Dong, Chao Lu, and Alan Pak Tao Lau 14.1 Introduction 473 14.2 OPM TECHNIQUES FOR DIRECT DETECTION SYSTEMS 482 14.3 OPM For Coherent Detection Systems 490 14.4 Integrating OPM Functionalities in Networking 499 14.5 Conclusions and Outlook 499 Acknowledgments 500 References 500 15 Rate-Adaptable Optical Transmission and Elastic Optical Networks 507 Patricia Layec, Annalisa Morea, Yvan Pointurier, and Jean-Christophe Antona 15.1 Introduction 507 15.2 Key Building Blocks 511 15.3 Practical Considerations for Elastic WDM Transmission 527 15.4 Opportunities for Elastic Technologies in Core Networks 530 15.5 Long Term Opportunities 534 15.6 Conclusions 539 Acknowledgments 539 References 539 16 Space-Division Multiplexing and MIMO Processing 547 Roland Ryf and Nicolas K. Fontaine 16.1 Space-Division Multiplexing in Optical Fibers 547 16.2 Optical Fibers for SDM Transmission 548 16.3 Optical Transmission in SDM Fibers with Low Crosstalk 551 16.4 MIMO-Based Optical Transmission in SDM Fibers 553 16.5 Impulse Response in SDM Fibers with Mode Coupling 558 16.6 MIMO-Based SDM Transmission Results 566 16.7 Optical Components for SDM Transmission 568 16.8 Conclusion 593 Acknowledgments 593 References 594 Index 609