Nonlinear Tolerance of 53.5-Gb/s Differential 6-ary PSK Surrounded by 10.7-Gb/s NRZ-OOK Neighbors in SMF and DSF Transmission Links

We demonstrate an optical transmission system based on a 53.5-Gb/s differential 6-ary phase-shift-keying (D6PSK) signal with copropagating 10.7-Gb/s nonreturn-to-zero (NRZ) on-off keying (OOK) channels over either 320-km-long single-mode fiber link with in-line dispersion compensation or 320-km-long dispersion-shifted fiber link, and compare its performances with that of a classical polarization-division-multiplexing differential quadrature phase-shift-keying (DQPSK)-based system. The results show that the nonlinear tolerance of the D6PSK signal outperforms that of the PDM-DQPSK signal in terms of the cross-phase modulation effect induced by the 10.7-Gb/s NRZ-OOK neighboring channels.