Regeneration of RZ-DPSK signals by fiber-based all-optical regenerators

Reshaping of return-to-zero differential-phase-shift keying (RZ-DPSK) signals by fiber-based all-optical 2R regenerators is numerically studied. Diffusion of the phase of the signal in the process of amplitude stabilization is assessed for two types of regenerators: one based on soliton compression followed by narrow-band filtering, and another based on ultrafast saturation of four-wave mixing (FWM) in parametric amplifier configuration. It is shown that the FWM-based regenerators induce small phase diffusion and they can improve RZ-DPSK transmission performance.