Simultaneous reshaping of OOK and DPSK signals by a fiber-based all-optical regenerator

Simultaneous reshaping of optically time-division-multiplexed RZ-OOK and RZ-DPSK signals by a fiber-based regenerator is numerically demonstrated. The regenerator utilizes the four-wave mixing (FWM) in a highly nonlinear fiber. A parametric amplifier configuration without wavelength conversion of the signal is assumed, in which ultra-fast saturation of the FWM interaction gives stabilization of signal amplitude with the signal phase principally maintained. The regenerator greatly improves the performance of OOK tributaries. Although the regenerator does not have the function of phase regeneration, it improves the DPSK signal quality when the signal power is relatively low where the amplitude noise is significant. Influence of the pump phase modulation on the regenerator performance is also examined.