High Spectral Density Optical Communication Technologies

Preface

Contents

Contributors

Part I Overview and System Technologies

1 Social Demand of New Generation Information Network: Introduction to High Spectral Density Optical Communication Technology

1.1 Achievements and Challenges of Fiber-Optic Communication Technology

1.2 Social Demands Requiring Advanced Photonic Network

1.3 Technical Issues for New Generation Network

1.4 Fundamental Problems of High Spectral Density Modulation Technology

References

2 Coherent Optical Communications: Historical Perspectives and Future Directions

2.1 History of Coherent Optical Communications

2.1.1 Coherent Optical Communication Systems 20 Years Ago

2.1.2 Revival of Coherent Optical Communications

2.2 Principle of Coherent Optical Detection

2.2.1 Coherent Detection

2.2.2 Heterodyne Receivers

2.2.3 Homodyne Receivers

2.2.4 Homodyne Receiver Employing Phase and Polarization Diversities

2.2.5 Carrier-to-Noise Ratio

2.3 Digital Signal Processing in Coherent Receivers

2.3.1 Basic Concept of the Digital Coherent Receiver

2.3.2 Sampling of the Signal and Clock Extraction

2.3.3 Phase Estimation

2.3.4 Polarization Alignment

2.3.5 Equalization of Inter-symbol Interference

2.4 Performance of the Digital Coherent Receiver

2.4.1 Optical Circuit for the Homodyne Receiver Comprising Phase and Polarization Diversities

2.4.2 Receiver Sensitivity

2.4.3 Polarization Sensitivity

2.4.4 Phase Noise Tolerance

2.4.5 Coherent Demodulation of Multi-level Encoded Signals

2.5 Challenges for the Future

References

3 Ultrahigh Spectral Density Coherent Optical Transmission Technologies

3.1 Introduction

3.2 Spectral Efficiency of QAM Signal and Shannon Limit

3.3 Fundamental Configuration and Key Components of QAM Coherent Optical Transmission

3.3.1 C2H2 Frequency-Stabilized Erbium-Doped Fiber Ring Laser

3.3.2 Optical PLL for Coherent Transmission Using Heterodyne Detection with Fiber Lasers

3.3.3 Optical IQ Modulator

3.3.4 Digital Demodulator

3.4 Single-Channel 1 Gsymbol/s, 128 QAM Transmission

3.4.1 1 Gsymbol/s, 128 QAM Transmission Setup

3.4.2 Transmission Results

3.4.3 SPM Compensation

3.4.4 Comparison with Theoretical OSNR Limit

3.5 128 QAM-FDM Transmission with a Spectral Efficiency of 10bit/s/Hz

3.6 64 QAM-OFDM Coherent Transmission

3.6.1 Principle of OFDM Transmission

3.6.2 24Gbit/s, 64 QAM-OFDM Coherent Transmission Experiment

3.7 Conclusion

References

4 ``Quasi Ultimate'' Technique

4.1 Introduction

4.2 Pilot Symbol Insertion Technique

4.2.1 8PSK Simulation

4.2.2 QPSK Homodyne Using Pilot Symbols

4.3 Polarization-Multiplexed Pilot Carrier Technique

4.3.1 Principle

4.3.2 QPSK Demonstration

4.3.3 8PSK Demonstration

4.4 ISI Digital Pre-equalization Technique for M-QAMs

4.4.1 Pre-equalization for ISI

4.4.2 16-QAM and 64-QAM Demonstration

4.5 Simulated Results in 256-QAM

References

5 High-Speed and High-Capacity Optical Transmission Systems

5.1 The Need for Capacity and Spectral Efficiency

5.2 Modulation at High Spectral Efficiencies

5.2.1 Signal Orthogonality in Optical Communications

5.2.2 The Evolution of Optical Modulation Formats

5.3 Theoretical Fiber Capacity Limits

5.4 Conclusion

References

Part II Advanced Modulation Formats

6 Multilevel Signaling with Direct Detection

6.1 Introduction

6.2 Combined Binary Detection

6.3 Receiver-Side Digital Signal Processing

6.4 Transmitter-Side Digital Signal Processing

6.5 Conclusions

References

7 High Spectral Efficiency Coherent Optical OFDM

7.1 Overview

7.1.1 Background

7.1.2 Organization of the Chapter

7.2 Signal Processing in Coherent Optical MIMO-OFDM

7.2.1 Representation of OFDM

7.3 Implementation of CO-OFDM

7.4 Representation of Coherent Optical MIMO-OFDM

7.5 High-order Modulation in CO-OFDM

7.5.1 BER Performance of Advanced Modulation Formats in AWGN

7.5.2 Simulation Results on Laser Phase Noise

7.5.3 Experimental Investigations of Phase Noise Effects

7.5.4 Laser Linewidth Effects

7.5.5 Non-linear Phase Noise from Optical Fiber Transmissions

7.6 Orthogonal-Band Multiplexing Using CO-OFDM

7.6.1 Principle of Orthogonal-Band-Multiplexed OFDM (OBM-OFDM)

7.6.2 Experimental Setup and Description

7.6.3 Experimental Results and Discussion

7.7 Conclusion

References

8 Polarization Division-Multiplexed Coherent Optical OFDM Transmission Enabled by MIMO Processing

8.1 Introduction

8.2 PDM Receiver with MIMO Processing

8.2.1 PDM-OFDM

8.2.2 MIMO Processing

8.2.3 MIMO OFDM Channel Estimation

8.3 10 × 122-Gb/s Transmission Experiment with PDM-OFDM

8.3.1 Experimental Setup

8.3.2 Experimental Results

8.4 Conclusion

References

9 No-Guard-Interval Coherent Optical OFDM with Frequency Domain Equalization

9.1 Introduction

9.2 High-Capacity Challenges and Modulation Format Alternatives

9.3 Concept of No-Guard-Interval OFDM

9.4 PDM No-Guard-Interval CO-OFDM Transmitter and Receiver Configuration

9.5 111Gbps No-Guard-Interval OFDM Transmitter and Receiver Performance

9.6 13.5-Tbps WDM Transmission Using 111-Gbps PDM No-Guard-Interval OFDM QPSK Format

9.7 Conclusions

References

10 QPSK-Based Transmission System: Trade-Offs Between Linear and Nonlinear Impairments

10.1 Introduction

10.2 Options of QPSK-Based Transceiver Implementation

10.3 DP Signal Impairment Due to PDL

10.4 Impact of Cross-Phase Modulationon SP- and DP-RZ-DQPSK Signals

10.5 XPM Tolerance Comparison between Direct and Coherent Detection Receivers

10.6 Summary

References

11 Real-Time Digital Coherent QPSK Transmission Technologies

11.1 Introduction

11.2 Algorithmic Requirements

11.3 Feasibility of Parallel Processing

11.4 Hardware Efficiency

11.5 Tolerance Against Feedback Delays

11.6 Technological Requirements

11.7 Real-time Implementations of Digital Coherent QPSK Receivers

References

12 Challenge for Full Control of Polarization in Optical Communication Systems

12.1 Introduction

12.2 Polarization Fluctuation in Single-Mode Fibers

12.3 Solutions for SOP Fluctuation

12.3.1 Polarization-Maintaining Fiber

12.3.2 Polarization Control Scheme

12.3.3 Polarization-Diversity Scheme

12.3.4 Polarization Scrambling Scheme

12.4 Evolutions of Technology for SOP Fluctuation Problem

References

Part III Opto-electronics Devices

13 Semiconductor Lasers for High-Density Optical Communication Systems

13.1 Requirements to Spectral Linewidth

13.2 Spectral Linewidth of Semiconductor Lasers

13.3 Reports of Narrow Spectral Linewidth Semiconductor Lasers

13.3.1 DFB and DBR Lasers

13.3.2 External Cavity Semiconductor Lasers

13.4 Comparison between Several types of Narrow Spectral Linewidth Semiconductor Lasers

13.5 Reported Technologies and Issues of Tunable Semiconductor Lasers

13.5.1 DFB Laser Array (Wavelength Selectable Laser)

13.5.2 Super Structure Grating or Sampled Grating DBR Laser

13.5.3 External Cavity Laser

13.5.4 Dynamic Wavelength Drift and its Suppression

13.5.5 Dependence of Wavelength Tuning Scheme on Spectral Linewidth

13.5.6 Wavelength Stability

13.6 Summary

References

14 Monolithic InP Photonic Integrated Circuits for Transmitting or Receiving Information with Augmented Fidelity or Spectral Efficiency

14.1 Introduction

14.2 InP basics

14.3 Transmitters

14.3.1 Increasing the Spectral Efficiency via Polarization

14.3.2 Increasing the Spectral Efficiency via Phase

14.3.3 Increasing the Spectral Efficiency via Multiple Levels

14.3.4 Compensating for Fiber Chromatic Dispersion

14.4 Receivers

14.5 Conclusions

References

15 Integrated Mach--Zehnder Interferometer-Based Modulators for Advanced Modulation Formats

15.1 Background

15.2 Optical Components for Vector Modulation Schemes

15.3 Phase Modulator

15.4 Mach--Zehnder Intensity Modulator

15.5 Integrated Modulators for High Data Rate Signal Generation

15.6 High-Speed Optical Multi-level Modulation Using DPMZM and QPMZM

References

16 Key Devices for High-Speed Optical Communication and Their Application to Transceiver Module

16.1 High-Speed Electrical Devices and Optical Devices

16.2 Integration of High-Speed Devices

16.3 Packaging of Electrical Devices and Optical Devices

16.4 High-Speed Transceivers

16.5 Future Directions for Devices and Transceiver Modules

References

17 Forward Error Correction

17.1 Basic Concepts and Terminology

17.2 First-Generation FEC

17.3 Second-Generation FEC

17.4 Third-Generation FEC

17.5 Comparison with the Shannon limit

17.6 FEC Error Count

References

Index