Modeling of nonlinearity in semiconductor optical amplifiers

Three nonlinear models of traveling-wave, semiconductor optical amplifiers are presented which are suitable for analysis and computer simulations of various lightwave communications systems. These models have increasing degrees of accuracy and complexity. They make it possible for a communications engineer, unfamiliar with the physics of such amplifiers, to compute, analytically or by numerical simulations, the input-output relations for virtually any form of optical signal. Examples are given for the nonlinear distortion associated with a variety of input signaling formats. The effects of amplified-spontaneous-emission (ASE) noise on the nonlinearity are also considered. It is shown that the forms of the models were not changed by adding the ASE noise, except for two simple parameter modifications