Nonlinear crosstalk between OTDM-OOK and DPSK signals in four-wave mixing wavelength conversion

We investigate the nonlinear crosstalk between a 10-Gb/s differential phase-shift keying (DPSK) signal and a 160-Gb/s optical time division multiplexing on-off keying (OTDM-OOK) signal in four-wave mixing (FWM) based wavelength conversion. Experimental results show that wavelength conversion of the DPSK signal is strongly susceptible to cross-phase modulation (XPM) caused by the OTDM-OOK signal. Error-free operation is achieved by keeping the OTDM-OOK signal orthogonally polarized to the DPSK signal and the pump and thus minimize the XPM. The influence of the DPSK signal on the wavelength conversion of the OTDM-OOK signal is negligible.