Details

<p>List of Contributors xv</p> <p>Preface xvii</p> <p><b>1 Introduction 1<br /></b><i>Xiang Zhou and Chongjin Xie</i></p> <p>1.1 High-Capacity Fiber Transmission Technology Evolution, 1</p> <p>1.2 Fundamentals of Coherent Transmission Technology, 4</p> <p>1.2.1 Concept of Coherent Detection, 4</p> <p>1.2.2 Digital Signal Processing, 5</p> <p>1.2.3 Key Devices, 7</p> <p>1.3 Outline of this Book, 8</p> <p>References, 9</p> <p><b>2 Multidimensional Optimized Optical Modulation Formats 13<br /></b><i>Magnus Karlsson and Erik Agrell</i></p> <p>2.1 Introduction, 13</p> <p>2.2 Fundamentals of Digital Modulation, 15</p> <p>2.2.1 System Models, 15</p> <p>2.2.2 Channel Models, 17</p> <p>2.2.3 Constellations and Their Performance Metrics, 18</p> <p>2.3 Modulation Formats and Their Ideal Performance, 20</p> <p>2.3.1 Format Optimizations and Comparisons, 21</p> <p>2.3.2 Optimized Formats in Nonlinear Channels, 30</p> <p>2.4 Combinations of Coding and Modulation, 31</p> <p>2.4.1 Soft-Decision Decoding, 31</p> <p>2.4.2 Hard-Decision Decoding, 37</p> <p>2.4.3 Iterative Decoding, 39</p> <p>2.5 Experimental Work, 40</p> <p>2.5.1 Transmitter Realizations and Transmission Experiments, 40</p> <p>2.5.2 Receiver Realizations and Digital Signal Processing, 45</p> <p>2.5.3 Formats Overview, 49</p> <p>2.5.4 Symbol Detection, 50</p> <p>2.5.5 Realizing Dimensions, 51</p> <p>2.6 Summary and Conclusions, 54</p> <p>References, 56</p> <p><b>3 Advances in Detection and Error Correction for Coherent Optical Communications: Regular, Irregular, and Spatially Coupled LDPC Code Designs 65<br /></b><i>Laurent Schmalen, Stephan ten Brink, and Andreas Leven</i></p> <p>3.1 Introduction, 65</p> <p>3.2 Differential Coding for Optical Communications, 67</p> <p>3.2.1 Higher-Order Modulation Formats, 67</p> <p>3.2.2 The Phase-Slip Channel Model, 69</p> <p>3.2.3 Differential Coding and Decoding, 71</p> <p>3.2.4 Maximum a Posteriori Differential Decoding, 78</p> <p>3.2.5 Achievable Rates of the Differentially Coded Phase-Slip</p> <p>Channel, 81</p> <p>3.3 LDPC-Coded Differential Modulation, 83</p> <p>3.3.1 Low-Density Parity-Check (LDPC) Codes, 85</p> <p>3.3.2 Code Design for Iterative Differential Decoding, 91</p> <p>3.3.3 Higher-Order Modulation Formats with V < Q, 100</p> <p>3.4 Coded Differential Modulation with Spatially Coupled LDPC Codes, 101</p> <p>3.4.1 Protograph-Based Spatially Coupled LDPC Codes, 102</p> <p>3.4.2 Spatially Coupled LDPC Codes with Iterative Demodulation, 105</p> <p>3.4.3 Windowed Differential Decoding of SC-LDPC Codes, 108</p> <p>3.4.4 Design of Protograph-Based SC-LDPC Codes for</p> <p>Differential-Coded Modulation, 108</p> <p>3.5 Conclusions, 112</p> <p>Appendix: LDPC-Coded Differential Modulation—Decoding Algorithms, 112</p> <p>Differential Decoding, 114</p> <p>LDPC Decoding, 115</p> <p>References, 117</p> <p><b>4 Spectrally Efficient Multiplexing: Nyquist-WDM 123<br /></b><i>Gabriella Bosco</i></p> <p>4.1 Introduction, 123</p> <p>4.2 Nyquist Signaling Schemes, 125</p> <p>4.2.1 Ideal Nyquist-WDM (Δf = Rs), 126</p> <p>4.2.2 Quasi-Nyquist-WDM (Δf > Rs), 128</p> <p>4.2.3 Super-Nyquist-WDM (Δf < Rs), 130</p> <p>4.3 Detection of a Nyquist-WDM Signal, 134</p> <p>4.4 Practical Nyquist-WDM Transmitter Implementations, 137</p> <p>4.4.1 Optical Nyquist-WDM, 139</p> <p>4.4.2 Digital Nyquist-WDM, 141</p> <p>4.5 Nyquist-WDM Transmission, 146</p> <p>4.5.1 Optical Nyquist-WDM Transmission Experiments, 148</p> <p>4.5.2 Digital Nyquist-WDM Transmission Experiments, 148</p> <p>4.6 Conclusions, 149</p> <p>References, 150</p> <p><b>5 Spectrally Efficient Multiplexing – OFDM 157<br /></b><i>An Li, Di Che, Qian Hu, Xi Chen, and William Shieh 5.1 OFDM Basics, 158</i></p> <p>5.2 Coherent Optical OFDM (CO-OFDM), 161</p> <p>5.2.1 Principle of CO-OFDM, 161</p> <p>5.3 Direct-Detection Optical OFDM (DDO-OFDM), 169</p> <p>5.3.1 Linearly Mapped DDO-OFDM, 169</p> <p>5.3.2 Nonlinearly Mapped DDO-OFDM (NLM-DDO-OFDM), 173</p> <p>5.4 Self-Coherent Optical OFDM, 174</p> <p>5.4.1 Single-Ended Photodetector-Based SCOH, 175</p> <p>5.4.2 Balanced Receiver-Based SCOH, 177</p> <p>5.4.3 Stokes Vector Direct Detection, 177</p> <p>5.5 Discrete Fourier Transform Spread OFDM System (DFT-S OFDM), 180</p> <p>5.5.1 Principle of DFT-S OFDM, 180</p> <p>5.5.2 Unique-Word-Assisted DFT-S OFDM (UW-DFT-S OFDM), 182</p> <p>5.6 OFDM-Based Superchannel Transmissions, 183</p> <p>5.6.1 No-Guard-Interval CO-OFDM (NGI-CO-OFDM) Superchannel, 184</p> <p>5.6.2 Reduced-Guard-Interval CO-OFDM (RGI-CO-OFDM) Superchannel, 186</p> <p>5.6.3 DFT-S OFDM Superchannel, 188</p> <p>5.7 Summary, 193</p> <p>References, 194</p> <p><b>6 Polarization and Nonlinear Impairments in Fiber Communication Systems 201<br /></b><i>Chongjin Xie</i></p> <p>6.1 Introduction, 201</p> <p>6.2 Polarization of Light, 202</p> <p>6.3 PMD and PDL in Optical Communication Systems, 206</p> <p>6.3.1 PMD, 206</p> <p>6.3.2 PDL, 208</p> <p>6.4 Modeling of Nonlinear Effects in Optical Fibers, 209</p> <p>6.5 Coherent Optical Communication Systems and Signal Equalization, 211</p> <p>6.5.1 Coherent Optical Communication Systems, 211</p> <p>6.5.2 Signal Equalization, 213</p> <p>6.6 PMD and PDL Impairments in Coherent Systems, 215</p> <p>6.6.1 PMD Impairment, 216</p> <p>6.6.2 PDL Impairment, 222</p> <p>6.7 Nonlinear Impairments in Coherent Systems, 228</p> <p>6.7.1 System Model, 229</p> <p>6.7.2 Homogeneous PDM-QPSK System, 230</p> <p>6.7.3 Hybrid PDM-QPSK and 10-Gb/s OOK System, 233</p> <p>6.7.4 Homogeneous PDM-16QAM System, 234</p> <p>6.8 Summary, 240</p> <p>References, 241</p> <p><b>7 Analytical Modeling of the Impact of Fiber Non-Linear Propagation on Coherent Systems and Networks 247<br /></b><i>Pierluigi Poggiolini, Yanchao Jiang, Andrea Carena, and Fabrizio Forghieri</i></p> <p>7.1 Why are Analytical Models Important?, 247</p> <p>7.1.1 What Do Professionals Need?, 247</p> <p>7.2 Background, 248</p> <p>7.2.1 Modeling Approximations, 249</p> <p>7.3 Introducing the GN–EGN Model Class, 260</p> <p>7.3.1 Getting to the GN Model, 260</p> <p>7.3.2 Towards the EGN Model, 265</p> <p>7.4 Model Selection Guide, 269</p> <p>7.4.1 From Model to System Performance, 269</p> <p>7.4.2 Point-to-Point Links, 270</p> <p>7.4.3 The Complete EGN Model, 272</p> <p>7.4.4 Case Study: Determining the Optimum System Symbol Rate, 286</p> <p>7.4.5 NLI Modeling for Dynamically Reconfigurable Networks, 289</p> <p>7.5 Conclusion, 294</p> <p>Acknowledgements, 295</p> <p>Appendix, 295</p> <p>A.1 The White-Noise Approximation, 295</p> <p>A.1 BER Formulas for the Most Common QAM Systems, 295</p> <p>A.2 The Link Function 𝜇, 296</p> <p>A.3 The EGN Model Formulas for the X2-X4 and M1-M3 Islands, 297</p> <p>A.4 Outline of GN–EGN Model Derivation, 299</p> <p>A.5 List of Acronyms, 303</p> <p>References, 305</p> <p><b>8 Digital Equalization in Coherent Optical Transmission Systems 311<br /></b><i>Seb Savory</i></p> <p>8.1 Introduction, 311</p> <p>8.2 Primer on the Mathematics of Least Squares FIR Filters, 312</p> <p>8.2.1 Finite Impulse Response Filters, 313</p> <p>8.2.2 Differentiation with Respect to a Complex Vector, 314</p> <p>8.2.3 Least Squares Tap Weights, 314</p> <p>8.2.4 Application to Stochastic Gradient Algorithms, 316</p> <p>8.2.5 Application to Wiener Filter, 317</p> <p>8.2.6 Other Filtering Techniques and Design Methodologies, 318</p> <p>8.3 Equalization of Chromatic Dispersion, 318</p> <p>8.3.1 Nature of Chromatic Dispersion, 318</p> <p>8.3.2 Modeling of Chromatic Dispersion in an Optical Fiber, 318</p> <p>8.3.3 Truncated Impulse Response, 319</p> <p>8.3.4 Band-Limited Impulse Response, 320</p> <p>8.3.5 Least Squares FIR Filter Design, 321</p> <p>8.3.6 Example Performance of the Chromatic Dispersion Compensating Filter, 321</p> <p>8.4 Equalization of Polarization-Mode Dispersion, 323</p> <p>8.4.1 Modeling of PMD, 324</p> <p>8.4.2 Obtaining the Inverse Jones Matrix of the Channel, 325</p> <p>8.4.3 Constant Modulus Update Algorithm, 325</p> <p>8.4.4 Decision-Directed Equalizer Update Algorithm, 326</p> <p>8.4.5 Radially Directed Equalizer Update Algorithm, 327</p> <p>8.4.6 Parallel Realization of the FIR Filter, 327</p> <p>8.4.7 Generalized 4 × 4 Equalizer for Mitigation of Frequency or Polarization-Dependent Loss and Receiver Skew, 328</p> <p>8.4.8 Example Application to Fast Blind Equalization of PMD, 328</p> <p>8.5 Concluding Remarks and Future Research Directions, 329</p> <p>Acknowledgments, 330</p> <p>References, 330</p> <p><b>9 Nonlinear Compensation for Digital Coherent Transmission 333<br /></b><i>Guifang Li</i></p> <p>9.1 Introduction, 333</p> <p>9.2 Digital Backward Propagation (DBP), 334</p> <p>9.2.1 How DBP Works, 334</p> <p>9.2.2 Experimental Demonstration of DBP, 335</p> <p>9.2.3 Computational Complexity of DBP, 336</p> <p>9.3 Reducing DBP Complexity for Dispersion-Unmanaged WDM Transmission, 339</p> <p>9.4 DBP for Dispersion-Managed WDM Transmission, 342</p> <p>9.5 DBP for Polarization-Multiplexed Transmission, 349</p> <p>9.6 Future Research, 350</p> <p>References, 351</p> <p><b>10 Timing Synchronization in Coherent Optical Transmission Systems 355<br /></b><i>Han Sun and Kuang-Tsan Wu</i></p> <p>10.1 Introduction, 355</p> <p>10.2 Overall System Environment, 357</p> <p>10.3 Jitter Penalty and Jitter Sources in a Coherent System, 359</p> <p>10.3.1 VCO Jitter, 359</p> <p>10.3.2 Detector Jitter Definitions and Method of Numerical Evaluation, 361</p> <p>10.3.3 Laser FM Noise- and Dispersion-Induced Jitter, 363</p> <p>10.3.4 Coherent System Tolerance to Untracked Jitter, 366</p> <p>10.4 Digital Phase Detectors, 368</p> <p>10.4.1 Frequency-Domain Phase Detector, 369</p> <p>10.4.2 Equivalence to the Squaring Phase Detector, 371</p> <p>10.4.3 Equivalence to Godard’s Maximum Sampled Power Criterion, 373</p> <p>10.4.4 Equivalence to Gardner’s Phase Detector, 374</p> <p>10.4.5 Second Class of Phase Detectors, 377</p> <p>10.4.6 Jitter Performance of the Phase Detectors, 378</p> <p>10.4.7 Phase Detectors for Nyquist Signals, 380</p> <p>10.5 The Chromatic Dispersion Problem, 383</p> <p>10.6 The Polarization-Mode Dispersion Problem, 386</p> <p>10.7 Timing Synchronization for Coherent Optical OFDM, 390</p> <p>10.8 Future Research, 391</p> <p>References, 392</p> <p><b>11 Carrier Recovery in Coherent Optical Communication Systems 395<br /></b><i>Xiang Zhou</i></p> <p>11.1 Introduction, 395</p> <p>11.2 Optimal Carrier Recovery, 397</p> <p>11.2.1 MAP-Based Frequency and Phase Estimator, 397</p> <p>11.2.2 Cramér–Rao Lower Bound, 398</p> <p>11.3 Hardware-Efficient Phase Recovery Algorithms, 399</p> <p>11.3.1 Decision-Directed Phase-Locked Loop (PLL), 399</p> <p>11.3.2 Mth-Power-Based Feedforward Algorithms, 401</p> <p>11.3.3 Blind Phase Search (BPS) Feedforward Algorithms, 405</p> <p>11.3.4 Multistage Carrier Phase Recovery Algorithms, 408</p> <p>11.4 Hardware-Efficient Frequency Recovery Algorithms, 416</p> <p>11.4.1 Coarse Auto-Frequency Control (ACF), 416</p> <p>11.4.2 Mth-Power-Based Fine FO Estimation Algorithms, 418</p> <p>11.4.3 Blind Frequency Search (BFS)-Based Fine FO Estimation Algorithm, 421</p> <p>11.4.4 Training-Initiated Fine FO Estimation Algorithm, 423</p> <p>11.5 Equalizer-Phase Noise Interaction and its Mitigation, 424</p> <p>11.6 Carrier Recovery in Coherent OFDM Systems, 429</p> <p>11.7 Conclusions and Future Research Directions, 430</p> <p>References, 431</p> <p><b>12 Real-Time Implementation of High-Speed Digital Coherent Transceivers 435<br /></b><i>Timo Pfau</i></p> <p>12.1 Algorithm Constraints, 435</p> <p>12.1.1 Power Constraint and Hardware Optimization, 436</p> <p>12.1.2 Parallel Processing Constraint, 438</p> <p>12.1.3 Feedback Latency Constraint, 440</p> <p>12.2 Hardware Implementation of Digital Coherent Receivers, 442</p> <p>References, 446</p> <p><b>13 Photonic Integration 447<br /></b><i>Po Dong and Sethumadhavan Chandrasekhar</i></p> <p>13.1 Introduction, 447</p> <p>13.2 Overview of Photonic Integration Technologies, 449</p> <p>13.3 Transmitters, 451</p> <p>13.3.1 Dual-Polarization Transmitter Circuits, 451</p> <p>13.3.2 High-Speed Modulators, 452</p> <p>13.3.3 PLC Hybrid I/Q Modulator, 455</p> <p>13.3.4 InP Monolithic I/Q Modulator, 455</p> <p>13.3.5 Silicon Monolithic I/Q Modulator, 457</p> <p>13.4 Receivers, 459</p> <p>13.4.1 Polarization Diversity Receiver Circuits, 459</p> <p>13.4.2 PLC Hybrid Receivers, 461</p> <p>13.4.3 InP Monolithic Receivers, 462</p> <p>13.4.4 Silicon Monolithic Receivers, 462</p> <p>13.4.5 Coherent Receiver with 120∘ Optical Hybrids, 465</p> <p>13.5 Conclusions, 467</p> <p>Acknowledgments, 467</p> <p>References, 467</p> <p><b>14 Optical Performance Monitoring for Fiber-Optic Communication Networks 473<br /></b><i>Faisal N. Khan, Zhenhua Dong, Chao Lu, and Alan Pak Tao Lau</i></p> <p>14.1 Introduction, 473</p> <p>14.1.1 OPM and Their Roles in Optical Networks, 474</p> <p>14.1.2 Network Functionalities Enabled by OPM, 475</p> <p>14.1.3 Network Parameters Requiring OPM, 477</p> <p>14.1.4 Desirable Features of OPM Techniques, 480</p> <p>14.2 OPM Techniques For Direct Detection Systems, 482</p> <p>14.2.1 OPM Requirements for Direct Detection Optical Networks, 482</p> <p>14.2.2 Overview of OPM Techniques for Existing Direct Detection Systems, 483</p> <p>14.2.3 Electronic DSP-Based Multi-Impairment Monitoring Techniques for Direct Detection Systems, 485</p> <p>14.2.4 Bit Rate and Modulation Format Identification Techniques for Direct Detection Systems, 488</p> <p>14.2.5 Commercially Available OPM Devices for Direct Detection Systems, 489</p> <p>14.2.6 Applications of OPM in Deployed Fiber-Optic Networks, 489</p> <p>14.3 OPM For Coherent Detection Systems, 490</p> <p>14.3.1 Non-Data-Aided OSNR Monitoring for Digital Coherent Receivers, 491</p> <p>14.3.2 Data-Aided (Pilot Symbols Based) OSNR Monitoring for Digital Coherent Receivers, 494</p> <p>14.3.3 OPM at the Intermediate Network Nodes Using Low-Cost Structures, 495</p> <p>14.3.4 OSNR Monitoring in the Presence of Fiber Nonlinearity, 496</p> <p>14.4 Integrating OPM Functionalities in Networking, 499</p> <p>14.5 Conclusions and Outlook, 499</p> <p>Acknowledgments, 500</p> <p>References, 500</p> <p><b>15 Rate-Adaptable Optical Transmission and Elastic Optical Networks 507<br /></b><i>Patricia Layec, Annalisa Morea, Yvan Pointurier, and Jean-Christophe  Antona</i></p> <p>15.1 Introduction, 507</p> <p>15.1.1 History of Elastic Optical Networks, 509</p> <p>15.2 Key Building Blocks, 511</p> <p>15.2.1 Optical Cross-Connect, 512</p> <p>15.2.2 Elastic Transponder, 513</p> <p>15.2.3 Elastic Aggregation, 515</p> <p>15.2.4 Performance Prediction, 516</p> <p>15.2.5 Resource Allocation Tools, 520</p> <p>15.2.6 Control Plane for Flexible Optical Networks, 524</p> <p>15.3 Practical Considerations for Elastic WDM Transmission, 527</p> <p>15.3.1 Flexible Transponder Architecture, 527</p> <p>15.3.2 Example of a Real-Time Energy-Proportional Prototype, 529</p> <p>15.4 Opportunities for Elastic Technologies in Core Networks, 530</p> <p>15.4.1 More Cost-Efficient Networks, 531</p> <p>15.4.2 More Energy Efficient Network, 532</p> <p>15.4.3 Filtering Issues and Superchannel Solution, 532</p> <p>15.5 Long Term Opportunities, 534</p> <p>15.5.1 Burst Mode Elasticity, 534</p> <p>15.5.2 Elastic Passive Optical Networks, 536</p> <p>15.5.3 Metro and Datacenter Networks, 537</p> <p>15.6 Conclusions, 539</p> <p>Acknowledgments, 539</p> <p>References, 539</p> <p><b>16 Space-Division Multiplexing and MIMO Processing 547<br /></b><i>Roland Ryf and Nicolas K. Fontaine</i></p> <p>16.1 Space-Division Multiplexing in Optical Fibers, 547</p> <p>16.2 Optical Fibers for SDM Transmission, 548</p> <p>16.3 Optical Transmission in SDM Fibers with Low Crosstalk, 551</p> <p>16.3.1 Digital Signal Processing Techniques for SDM Fibers with Low Crosstalk, 552</p> <p>16.4 MIMO-Based Optical Transmission in SDM Fibers, 553</p> <p>16.5 Impulse Response in SDM Fibers with Mode Coupling, 558</p> <p>16.5.1 Multimode Fibers with no Mode Coupling, 561</p> <p>16.5.2 Multimode Fibers with Weak Coupling, 561</p> <p>16.5.3 Multimode Fibers with Strong Mode Coupling, 565</p> <p>16.5.4 Multimode Fibers: Scaling to Large Number of Modes, 566</p> <p>16.6 MIMO-Based SDM Transmission Results, 566</p> <p>16.6.1 Digital Signal Processing for MIMO Transmission, 567</p> <p>16.7 Optical Components for SDM Transmission, 568</p> <p>16.7.1 Characterization of SDM Systems and Components, 570</p> <p>16.7.2 Swept Wavelength Interferometry for Fibers with Multiple Spatial Paths, 571</p> <p>16.7.3 Spatial Multiplexers, 576</p> <p>16.7.4 Photonic Lanterns, 578</p> <p>16.7.5 Spatial Diversity for SDM Components and Component sharing, 582</p> <p>16.7.6 Wavelength-Selective Switches for SDM, 583</p> <p>16.7.7 SDM Fiber Amplifiers, 590</p> <p>16.8 Conclusion, 593</p> <p>Acknowledgments, 593</p> <p>References, 594</p> <p>Index 609</p>

<p><b>Xiang Zhou</b> is a Tech Lead within Google Platform Advanced Technology. Before joining Google, he was with AT&T Labs, conducting research on various aspects of optical transmission and photonics networking technologies. Dr. Zhou is an OSA fellow and an associate editor for <i>Optics Express</i>. He has extensive publications in the field of optical communications.</p> <p><b>Chongjin Xie</b> is a Senior Director at Ali Infrastructure Service, Alibaba Group. Before joining Alibaba Group, he was a Distinguished Member of Technical Staff at Bell Labs, Alcatel-Lucent. Dr. Xie is a fellow of OSA and senior member of IEEE. He is an associate editor of the <i>Journal of Lightwave Technology</i> and has served in various conference committees.

<p><b>Presents the technological advancements that enable high spectral-efficiency and high-capacity fiber-optic communication systems and networks</b></p> <p>This book examines key technology advances in high spectral-efficiency fiber-optic communication systems and networks, enabled by the use of coherent detection and digital signal processing (DSP). The first of this book’s 16 chapters is a detailed introduction. Chapter 2 reviews the modulation formats, while Chapter 3 focuses on detection and error correction technologies for coherent optical communication systems. Chapters 4 and 5 are devoted to Nyquist-WDM and orthogonal frequency-division multiplexing (OFDM). In chapter 6, polarization and nonlinear impairments in coherent optical communication systems are discussed. The fiber nonlinear effects in a non-dispersion-managed system are covered in chapter 7. Chapter 8 describes linear impairment equalization and Chapter 9 discusses various nonlinear mitigation techniques. Signal synchronization is covered in Chapters 10 and 11. Chapter 12 describes the main constraints put on the DSP algorithms by the hardware structure. Chapter 13 addresses the funda mental concepts and recent progress of photonic integration. Optical performance monitoring and elastic optical network technology are the subjects of Chapters 14 and 15. Finally, Chapter 16 discusses spatial-division multiplexing and MIMO processing technology, a potential solution to solve the capacity limit of single-mode fibers. <ul><li>Contains basic theories and up-to-date technology advancements in each chapter</li> <li>Describes how capacity-approaching coding schemes based on low-density parity check (LDPC) and spatially coupled LDPC codes can be constructed by combining iterative demodulation and decoding</li> <li>Demonstrates that fiber nonlinearities can be accurately described by some analytical models, such as GN-EGN model</li> <li>Presents impairment equalization and mitigation techniques</li></ul> <p><i>Enabling Technologies for High Spectral-efficiency Coherent Optical Communication Networks</i> is a reference for researchers, engineers, and graduate students.

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