Bit-Rate Flexible Demodulation of DPSK Signals Based on Phase Sensitive Gain in Cascaded Four-Wave Mixing

We demonstrate bit-rate flexible demodulation of differential phase-shift keying (DPSK) signals in a linear structure. The demodulator utilizes a tunable optical delay based on the combination of wavelength conversion in a photonic crystal fiber and dispersion in a short section of single-mode fiber. Error-free demodulations for return-to-zero-DPSK signals at both 25 and 40 Gb/s have been successfully achieved.