Fiber nonlinearity mitigation using optical phase conjugation based on inter-modal FWM

We experimentally demonstrate an all-optical nonlinear-impairment mitigation by a mid-link optical phase conjugation based on inter-modal four-wave mixing in a 2-mode graded-index few-mode fiber. We transmit a single-channel 32-GBd single-polarization 16QAM signal over a dispersion-managed 800-km single-mode fiber link. Q 2 -factor improvement of ∼0.9 dB is achieved.