Wavelength-maintaining polarization-insensitive all-optical 3R regenerator

High-rate long-haul fiber communications systems will require high-speed efficient signal regeneration. By introducing a simple semiconductor-optical-amplifier wavelength converter into the folded ultrafast nonlinear interferometer, we demonstrate a polarization-insensitive wavelength-maintaining 3R all-optical regenerator. The extinction ratio between the on and off states is 21 dB. Bit-error rate data show no error floor and <0.3-dB power penalty when compared with a baseline measurement. Moreover, changes in input polarization cause no change in performance. The regenerator maintained a constant polarization and constant output power, independent of the input polarization.