Preconversion phase modulation of input differential phase-shift-keying signals for wavelength conversion and multicasting applications using phase-modulated pumps.

We demonstrate a method to use phase-modulated pumps for multicasting of return-to-zero differential phase-shift keying (RZ-DPSK) signals. The method uses phase modulation of the input signal along with the co-phase-modulated pumps prior to wavelength conversion. Nine copies of a 50 Gbit/s RZ-DPSK data signal are generated via four-wave mixing with an average conversion efficiency of ∼0 dB. An average receiver sensitivity penalty of ∼1.9 dB is observed at a bit-error rate of 10(-9) with a worst case of 2.3 dB. The effects of synchronization errors and phase-modulation frequencies up to 5 GHz are investigated.