Extremely High Dynamic Outer Extinction Ratio (9.7 dB) of 56-Gb/s PAM-4 with EA-DFB Lasers by Optical Orthogonal Polarization-Multiplexing

The highest dynamic outer extinction ratio (9.7 dB) of 56-Gb/s PAM-4 waveform is firstly achieved by employing optical orthogonal polarization-multiplexing with 1.3-pm NRZ driven EA-DFB lasers. High extinction ratio of PAM-4 improves the received sensitivity (2 dB), as compared with the conventional method.