Phase regeneration of QPSK signal in SOA using single-stage, wavelength converting PSA

We demonstrate, for the first time, all-optical phase regeneration of a quaternary phase shift keying signal through phase sensitive amplification in nonlinear semiconductor optical amplifiers (SOAs), using a scheme only previously demonstrated in highly nonlinear fibre. We make use of a highly tunable phase quantizing scheme to circumvent some of the limitations imposed by the use of SOAs and show that it may function in either a conjugating or nonconjugating manner.