Modeling of linear and nonlinear coupling in multiple-mode fiber optic transmission with MIMO signal processing

We discuss the modeling of linear and nonlinear signal propagation in the multi-mode fiber channel. Specifically, we introduce a generalized Stokes-space representation to describe signal evolution in such fibers and discuss the effect of modal dispersion representing the delay spread. We show that this phenomenon is described by a single real-valued vector whose modulus is Nakagami distributed. Furthermore, we describe nonlinear propagation in multi-mode fibers, and show that in realistic scenarios it can be modeled by means of coupled generalized Manakov equations.