Channel Model and Upper Bound on the Information Capacity of the Fiber Optical Communication Channel Based on the Effects of XPM Induced Nonlinearity

An upper bound to the information capacity of a wavelength-division multi- plexed optical fiber communication system is derived in a model incorporating the nonlinear propagation effects of cross-phase modulation (XPM). This work is based on the paper by Mitra et al., finding lower bounds to the channel capacity, in which physical models for propagation are used to calculate statistical properties of the conditional probability distribution relating input and output in a single WDM channel. In this paper we present a tractable channel model incorporating the effects of cross phase modulation. Using this model we find an upper bound to the information capacity of the fiber optical communication channel at high SNR. The results provide physical insight into the manner in which nonlinearities degrade the information capacity.