Optically enhanced pump-phase noise in mid-link optical parametric phase conjugation

This paper discusses the impact of pump-phase noise in the χ⁽²⁾-based optical parametric amplification process on the phase-conjugated idler. We show that the dispersive fiber propagation of the phase-conjugated idler causes the optically enhanced pump-phase noise (OEPN) effect including a group-velocity jitter. The signal penalty caused by the OEPN in the mid-link optical phase conjugation systems was quantified analytically and proved by numerical simulations. We also experimentally evaluated the OEPN with an optical parametric phase conjugator using periodically poled LiNbO₃ waveguides. With a 96-Gbaud probabilistically constellation-shaped 64QAM signal, the experimental results were in good agreement with the analytically derived penalty in a standard single-mode fiber link up to 800 km.