High Spectral Density Optical Communication Technologies (eBook)

Preface 6
Contents 8
Contributors 10
Part I Overview and System Technologies 12
1 Social Demand of New Generation Information Network: Introduction to High Spectral Density Optical Communication Technology 13
1.1 Achievements and Challenges of Fiber-Optic Communication Technology 13
1.2 Social Demands Requiring Advanced Photonic Network 14
1.3 Technical Issues for New Generation Network 17
1.4 Fundamental Problems of High Spectral Density Modulation Technology 18
References 19
2 Coherent Optical Communications: Historical Perspectives and Future Directions 21
2.1 History of Coherent Optical Communications 21
2.1.1 Coherent Optical Communication Systems 20 Years Ago 22
2.1.2 Revival of Coherent Optical Communications 25
2.2 Principle of Coherent Optical Detection 30
2.2.1 Coherent Detection 30
2.2.2 Heterodyne Receivers 31
2.2.3 Homodyne Receivers 33
2.2.4 Homodyne Receiver Employing Phase and Polarization Diversities 36
2.2.5 Carrier-to-Noise Ratio 38
2.3 Digital Signal Processing in Coherent Receivers 40
2.3.1 Basic Concept of the Digital Coherent Receiver 40
2.3.2 Sampling of the Signal and Clock Extraction 42
2.3.3 Phase Estimation 42
2.3.4 Polarization Alignment 44
2.3.5 Equalization of Inter-symbol Interference 50
2.4 Performance of the Digital Coherent Receiver 52
2.4.1 Optical Circuit for the Homodyne Receiver Comprising Phase and Polarization Diversities 53
2.4.2 Receiver Sensitivity 54
2.4.3 Polarization Sensitivity 55
2.4.4 Phase Noise Tolerance 55
2.4.5 Coherent Demodulation of Multi-level Encoded Signals 57
2.5 Challenges for the Future 58
References 58
3 Ultrahigh Spectral Density Coherent Optical Transmission Technologies 60
3.1 Introduction 60
3.2 Spectral Efficiency of QAM Signal and Shannon Limit 61
3.3 Fundamental Configuration and Key Components of QAM Coherent Optical Transmission 64
3.3.1 C2H2 Frequency-Stabilized Erbium-Doped Fiber Ring Laser 66
3.3.2 Optical PLL for Coherent Transmission Using Heterodyne Detection with Fiber Lasers 68
3.3.3 Optical IQ Modulator 71
3.3.4 Digital Demodulator 72
3.4 Single-Channel 1 Gsymbol/s, 128 QAM Transmission 74
3.4.1 1 Gsymbol/s, 128 QAM Transmission Setup 74
3.4.2 Transmission Results 75
3.4.3 SPM Compensation 76
3.4.4 Comparison with Theoretical OSNR Limit 78
3.5 128 QAM-FDM Transmission with a Spectral Efficiency of 10bit/s/Hz 79
3.6 64 QAM-OFDM Coherent Transmission 82
3.6.1 Principle of OFDM Transmission 82
3.6.2 24Gbit/s, 64 QAM-OFDM Coherent Transmission Experiment 83
3.7 Conclusion 87
References 87
4 ``Quasi Ultimate'' Technique 90
4.1 Introduction 90
4.2 Pilot Symbol Insertion Technique 92
4.2.1 8PSK Simulation 92
4.2.2 QPSK Homodyne Using Pilot Symbols 94
4.3 Polarization-Multiplexed Pilot Carrier Technique 98
4.3.1 Principle 98
4.3.2 QPSK Demonstration 99
4.3.3 8PSK Demonstration 102
4.4 ISI Digital Pre-equalization Technique for M-QAMs 104
4.4.1 Pre-equalization for ISI 104
4.4.2 16-QAM and 64-QAM Demonstration 105
4.5 Simulated Results in 256-QAM 108
References 110
5 High-Speed and High-Capacity Optical Transmission Systems 112
5.1 The Need for Capacity and Spectral Efficiency 112
5.2 Modulation at High Spectral Efficiencies 114
5.2.1 Signal Orthogonality in Optical Communications 115
5.2.2 The Evolution of Optical Modulation Formats 118
5.3 Theoretical Fiber Capacity Limits 128
5.4 Conclusion 131
References 132
Part II Advanced Modulation Formats 137
6 Multilevel Signaling with Direct Detection 138
6.1 Introduction 138
6.2 Combined Binary Detection 139
6.3 Receiver-Side Digital Signal Processing 141
6.4 Transmitter-Side Digital Signal Processing 143
6.5 Conclusions 146
References 146
7 High Spectral Efficiency Coherent Optical OFDM 148
7.1 Overview 148
7.1.1 Background 148
7.1.2 Organization of the Chapter 151
7.2 Signal Processing in Coherent Optical MIMO-OFDM 151
7.2.1 Representation of OFDM 152
7.3 Implementation of CO-OFDM 155
7.4 Representation of Coherent Optical MIMO-OFDM 158
7.5 High-order Modulation in CO-OFDM 160
7.5.1 BER Performance of Advanced Modulation Formats in AWGN 160
7.5.2 Simulation Results on Laser Phase Noise 161
7.5.3 Experimental Investigations of Phase Noise Effects 162
7.5.4 Laser Linewidth Effects 164
7.5.5 Non-linear Phase Noise from Optical Fiber Transmissions 164
7.6 Orthogonal-Band Multiplexing Using CO-OFDM 167
7.6.1 Principle of Orthogonal-Band-Multiplexed OFDM (OBM-OFDM) 167
7.6.2 Experimental Setup and Description 168
7.6.3 Experimental Results and Discussion 169
7.7 Conclusion 171
References 172
8 Polarization Division-Multiplexed Coherent Optical OFDM Transmission Enabled by MIMO Processing 174
8.1 Introduction 174
8.2 PDM Receiver with MIMO Processing 175
8.2.1 PDM-OFDM 175
8.2.2 MIMO Processing 176
8.2.3 MIMO OFDM Channel Estimation 178
8.3 10 × 122-Gb/s Transmission Experiment with PDM-OFDM 179
8.3.1 Experimental Setup 179
8.3.2 Experimental Results 182
8.4 Conclusion 184
References 184
9 No-Guard-Interval Coherent Optical OFDM with Frequency Domain Equalization 186
9.1 Introduction 186
9.2 High-Capacity Challenges and Modulation Format Alternatives 187
9.3 Concept of No-Guard-Interval OFDM 188
9.4 PDM No-Guard-Interval CO-OFDM Transmitter and Receiver Configuration 191
9.5 111Gbps No-Guard-Interval OFDM Transmitter and Receiver Performance 193
9.6 13.5-Tbps WDM Transmission Using 111-Gbps PDM No-Guard-Interval OFDM QPSK Format 194
9.7 Conclusions 195
References 195
10 QPSK-Based Transmission System: Trade-Offs Between Linear and Nonlinear Impairments 198
10.1 Introduction 198
10.2 Options of QPSK-Based Transceiver Implementation 199
10.3 DP Signal Impairment Due to PDL 201
10.4 Impact of Cross-Phase Modulationon SP- and DP-RZ-DQPSK Signals 203
10.5 XPM Tolerance Comparison between Direct and Coherent Detection Receivers 206
10.6 Summary 208
References 209
11 Real-Time Digital Coherent QPSK Transmission Technologies 210
11.1 Introduction 210
11.2 Algorithmic Requirements 210
11.3 Feasibility of Parallel Processing 211
11.4 Hardware Efficiency 213
11.5 Tolerance Against Feedback Delays 213
11.6 Technological Requirements 216
11.7 Real-time Implementations of Digital Coherent QPSK Receivers 217
References 219
12 Challenge for Full Control of Polarization in Optical Communication Systems 221
12.1 Introduction 221
12.2 Polarization Fluctuation in Single-Mode Fibers 222
12.3 Solutions for SOP Fluctuation 223
12.3.1 Polarization-Maintaining Fiber 223
12.3.2 Polarization Control Scheme 224
12.3.3 Polarization-Diversity Scheme 226
12.3.4 Polarization Scrambling Scheme 229
12.4 Evolutions of Technology for SOP Fluctuation Problem 229
References 230
Part III Opto-electronics Devices 232
13 Semiconductor Lasers for High-Density Optical Communication Systems 233
13.1 Requirements to Spectral Linewidth 233
13.2 Spectral Linewidth of Semiconductor Lasers 235
13.3 Reports of Narrow Spectral Linewidth Semiconductor Lasers 238
13.3.1 DFB and DBR Lasers 238
13.3.2 External Cavity Semiconductor Lasers 241
13.4 Comparison between Several types of Narrow Spectral Linewidth Semiconductor Lasers 241
13.5 Reported Technologies and Issues of Tunable Semiconductor Lasers 242
13.5.1 DFB Laser Array (Wavelength Selectable Laser) 244
13.5.2 Super Structure Grating or Sampled Grating DBR Laser 244
13.5.3 External Cavity Laser 246
13.5.4 Dynamic Wavelength Drift and its Suppression 247
13.5.5 Dependence of Wavelength Tuning Scheme on Spectral Linewidth 248
13.5.6 Wavelength Stability 250
13.6 Summary 251
References 251
14 Monolithic InP Photonic Integrated Circuits for Transmitting or Receiving Information with Augmented Fidelity or Spectral Efficiency 254
14.1 Introduction 254
14.2 InP basics 256
14.3 Transmitters 260
14.3.1 Increasing the Spectral Efficiency via Polarization 261
14.3.2 Increasing the Spectral Efficiency via Phase 263
14.3.3 Increasing the Spectral Efficiency via Multiple Levels 268
14.3.4 Compensating for Fiber Chromatic Dispersion 269
14.4 Receivers 271
14.5 Conclusions 272
References 273
15 Integrated Mach--Zehnder Interferometer-Based Modulators for Advanced Modulation Formats 275
15.1 Background 275
15.2 Optical Components for Vector Modulation Schemes 277
15.3 Phase Modulator 279
15.4 Mach--Zehnder Intensity Modulator 280
15.5 Integrated Modulators for High Data Rate Signal Generation 281
15.6 High-Speed Optical Multi-level Modulation Using DPMZM and QPMZM 283
References 286
16 Key Devices for High-Speed Optical Communication and Their Application to Transceiver Module 289
16.1 High-Speed Electrical Devices and Optical Devices 289
16.2 Integration of High-Speed Devices 294
16.3 Packaging of Electrical Devices and Optical Devices 299
16.4 High-Speed Transceivers 300
16.5 Future Directions for Devices and Transceiver Modules 302
References 303
17 Forward Error Correction 304
17.1 Basic Concepts and Terminology 304
17.2 First-Generation FEC 309
17.3 Second-Generation FEC 312
17.4 Third-Generation FEC 315
17.5 Comparison with the Shannon limit 326
17.6 FEC Error Count 329
References 331
Index 335