Dependence of nonlinear interference on mode dispersion and modulation format in strongly-coupled SDM transmissions

Abstract

We study the role of the modulation format in the interaction between mode dispersion and the fiber nonlinear interference (NLI) in space-division multiplexed (SDM) systems with strongly-coupled spatial modes. We show that the interplay between mode dispersion and the modulation format has a significant impact on the magnitude of cross-phase modulation (XPM). We propose a simple formula that accounts for the modulation-format dependence of the XPM variance in the presence of arbitrary levels of mode dispersion, thus extending the ergodic Gaussian noise model.