Demonstration of phase-regeneration of DPSK signals based on phase-sensitive amplification

Amplification and simultaneous phase regeneration of DPSK signals is demonstrated using a phase-sensitive amplifier. Phase-sensitive gain is achieved in a Sagnac fiber interferometer comprised of nonpolarization maintaining, highly nonlinear fiber operating in the un-depleted pump regime. Both the pump and signal are RZ-DPSK pulse trains. The amplifier is capable of producing greater than 13 dB of phase-sensitive gain for an average pumping power of 100 mW, and easily reduces the BER of the regenerated DPSK signal by two orders of magnitude compared to the un-regenerated signal, corresponding to a negative power penalty of 2 dB. Careful optimization of the regenerator reveals much stronger BER Improvement.