Noise Analysis of Zero-Forcing Nonlinear Equalizers for Coherent WDM Systems

We explore the fundamental limits on the achievable information rate of fiber-optic coherent transmission systems equipped with ideal zero-forcing nonlinear equalizer (ZFNLE). In the absence of amplifier noise, the ZFNLE forces the nonlinear signal-signal distortions to zero. If amplifier noise is included in the analysis, the equalization performance is severely limited by the nonlinear interactions between signal and noise both in fiber and inside the nonlinear equalizers. We build upon our previously developed theory of nonlinear signal-noise interactions, and compute the AIR due to ZFNLE for a variety of system parameters.