Modulation instability induced resonant four-wave mixing in WDM systems

We present an experimental observation of modulation instability (MI) impairments on a two-channel wavelength-division-multiplexed (WDM) system at 2.5 Gb/s per channel repeaterless link comprising 100 km of dispersion shifted fiber. When the channel spacing is close to the modulation instability frequency, channel depletion due to four-wave-mixing (FWM) interactions is resonantly enhanced and becomes the main source of system performance degradation. Numerical simulations agree well with the experiment and confirm that this effect dominates over the well known effect of MI amplification of noise. We discuss the influence of MI-induced resonant FWM as a function of channel spacing on WDM systems operating in the anomalous dispersion regime.