Chapter 5: Modeling and mitigation of nonlinear effects in optical fiber systems

This chapter provides a description of the most recent modeling activity in optical communications carried out in the Italian academia, which culminated in what is known as the Gaussian Noise (GN) model and its variants. The GN model has become nowadays the de-facto industry reference model for design and performance prediction of modern long-haul dispersion-uncompensated coherent optical systems and networks [1, 2]. Moreover, the chapter presents some recent results on fiber nonlinearity mitigation, focusing on digital backpropagation and constellation shaping strategies, and describes some bounding techniques that have been recently proposed to study the capacity limits of the nonlinear optical fiber channel.