All-optical regeneration of differential phase-shift keyed signals is demonstrated experimentally. Phase-preserving amplitude regeneration can be achieved by exploiting gain saturation in a fiber optical parametric amplifier, either with or without wavelength conversion. Phase regeneration requires use of phase-sensitive amplifiers, based on either four-wave mixing or nonlinear interferometers, both of which offer the possibility of combining phase and amplitude regeneration in a single device. Both implementations are investigated experimentally.
Polarization insensitive all-optical carrier recovery scheme from BPSK data is proposed and demonstrated in experiment
for the first time. The proposed scheme uses a degenerate optical parametric oscillator built with phase sensitive
All-optical regeneration of differential phase-shift keyed signals based on phase-sensitive amplification in a nonlinear fiber Sagnac interferometer is described. Nearly ideal phase regeneration can be achieved in the undepleted pump regime, with output differential phase noise limited only by fast fluctuations of the pump phase relative to the DPSK signal. Operating in the depleted pump regime offers the possibility of simultaneously regenerating both phase and amplitude information of DPSK signals while providing low noise, phase-sensitive gain.