Scheme for differential quadrature phase-shift keying/quadrature phase-shift keying signal all-optical regeneration based on phase-sensitive amplification

The performance of a scheme for all-optical regeneration of differential quadrature phase-shift keying (DQPSK) and quadrature phase-shift keying signals using phase-sensitive amplifiers (PSAs) is investigated through numerical simulation. The results show that both phase and amplitude noises of 40 Gb/s RZ-DQPSK signals are significantly suppressed after regeneration by leveraging the ability of PSAs to provide phase and amplitude regenerative amplification. The phase Q factor is also defined to evaluate the performance of regenerated signals, and it is found that the phase Q factor after regeneration is improved by about 3 dB.