Research On Phase Regeneration For MPSK Signals Based On Phase Sensitive Amplification

To meet the growing demands on the network capacity,spectrally efficient modulation formats, such as multilevel phase shift keying modulaition(MPSK),are considerd as the most practical solution to achieve high capacity and focused on much attention.Although MPSK signal shows enhanced performance in spectral efficiency, it is easy to be impacted by nonlinear phase noise which is generated by the conversion of amplified spontaneous emission noise from optical amplifiers into phase fluctuations via the Kerr nonlinearity in transmission fibers. Therefore, it is important to regenerate MPSK signals in optical transmission systems. At present,all optical regeneration technology for MPSK formats is mainly based on phase sensitive amplifier(PSA). And most of them are on the research of binary phase shift keying(BPSK) and quadrature phase-shift keying(QPSK), while the other advanced modulation formats such as eight phase-shift keying(8PSK) are less studied. In this case, we studied the all optical regeneration technology for QPSK and 8PSK in high-nonlinearity optical fiber(HNLF).The main contents of this article are as follows:1, we did a wide range of research on signal regeneration technology based on PSA to find the shortcomings and deficiencies in current research. According to these issues ,we proposed a phase regeneration scheme with high efficiency for MPSK signals based on two-mode PSA in HNLF. As compared to the conventional two-mode PSA, we utilize two phase-coherent pumps which are generated by tow FWM combs. In this case, high-order harmonics are replaced by lower-order harmonics, which solve the shortcomings of low four-wave mixing efficiency.2,the principle of signal regeneration based on PSA in HNLF is analyzed theoretically. And according to the theory of PSA, we proposed the theory of phase regeneration for MPSK signals.3,in this paper, phase regeneration of 10-Gb/s QPSK and 30-Gb/s 8PSK using this PSA scheme is verified via simulations. As compared to the FWM conversion efficiency of conventional two-mode PSA which is only 3.51%, our scheme can achieve the maximum of 20.8%.