A Novel Scheme to Generate 112.8-Gb/s PM-RZ-64QAM Optical Signal

We propose and experimentally demonstrate a novel scheme to generate eight-level electrical signals for a high-speed 64 quadrature amplitude modulation (64QAM) optical signal. The required optical signal-to-noise ratio at a bit-error rate of 2 x 10
^-3
for the single- (56.4 Gb/s) and dual-polarization (112.8 Gb/s) return-to-zero 64QAM is 21 and 26.5 dB, respectively.