Cross-Phase Modulation Mitigation in Phase-Sensitive Amplifier Links

We experimentally investigate a wavelength-division multiplexing (WDM) system with a single span of 80 km standard single-mode fiber (SSMF) and a phase-sensitive amplifier (PSA) as a pre-amplifier. Using two channels spaced 25 GHz apart with single-polarization 10-Gbaud quadrature phase-shift keying (QPSK) signal, we show quantitatively that a PSA can mitigate self-phase modulation (SPM) and cross-phase modulation (XPM). With three single-polarization 10-Gbaud QPSK channels spaced 12.5 GHz apart, we verify that PSA can mitigate XPM and also determine an allowed span loss increase of 9.5 dB for the center channel with correlated edge channels for the PSA compared to the phase-insensitive amplifier (PIA) due to the combined improvement from low-noise amplification and nonlinearity mitigation.