n 100 Gbit/s Transmission Issues 9.2.1 Optical Signal to Noise Ratio Reduction 9.2.2 Fiber Chromatic Dispersion 9.2.2.1 Impact of Chromatic Dispersion on 100 Gbit/s Transmission 9.2.2.2 Tunable Optical Dispersion Compensator 9.2.3 Fiber Polarization Mode Dispersion 9.2.3.1 Impact of Polarization Mode Dispersion on 100 Gbit/s Transmission 9.2.3.2 Polarization Mode Dispersion Compensation 9.2.4 Other Limiting Factors 9.2.4.1 Fiber Nonlinear Propagation 9.2.4.2 Timing Jitter 9.2.4.3 Electrical Front End Adaptation Contents Multilevel Optical Transmission 9.3.1 Optical Instantaneous Multilevel Modulation 9.3.2 Practical Multilevel Transmitters 9.3.2.1 Multilevel Differential Phase Modulation (M-DPSK) 9.3.2.2 Multilevel Quadrature Amplitude Modulation (M-QAM) 9.3.2.3 Multilevel Polarization Modulation (M-PolSK) 9.3.2.4 Multilevel Four Quadrature Amplitude Modulation (M-4QAM) 9.3.3 Multilevel Modulation Receivers 9.3.3.1 Four Quadrature Receiver 9.3.3.2 M-DPSK Optimum Receiver 9.3.3.3 M-PolSK Receivers 9.3.4 Ideal Performances of Multilevel Systems 9.3.4.1 M-QAM and M-4QAM with Quadrature Receiver 9.3.4.2 M-PolSK with Stokes Parameters Receiver 9.3.4.3 M-DPSK with Direct Detection Receiver 9.3.4.4 Comparison among Different Modulation Formats 9.3.5 Coherent Receivers Sensitivity to Phase and Polarization Fluctuations 9.3.5.1 Phase Noise Penalty for Coherent Quadrature Receiver 9.3.5.2 Depolarization Penalty for Coherent Quadrature Receiver Alternative and Complementary Transmission Techniques 9.4.1 Orthogonal Frequency Division Multiplexing 9.4.2 Polarization Division Multiplexing 9.4.3 Channel and Pulse Polarization Diversity Design Rules for 100 Gbit/s Long Haul Transmission Systems 9.5.1 Practical Multilevel Systems: Transmitting 100 Gbit/s on a Gbit/s Line 9.5.1.1 Power Budget 9.5.1.2 Penalty Analysis 9.5.2 Practical Multilevel Systems: Transmitting 100 Gbit/s on a 10 Gbit/s Line by 4QAM 9.5.2.1 Ideal Signal to Noise Ratio Requirements 9.5.2.2 Penalties Analysis 9.5.3 Practical Multilevel Systems: Transmitting 100 