Analysis of nonuniform nonlinear distributed feedback structures using a simple numerical approach

A simple numerical approach previously proposed for calculating the input-intensity dependence of the reflectivity and transmissivity of a nonlinear dielectric slab for incident plane electromagnetic waves is adopted for analyzing nonuniform nonlinear distributed feedback (NLDFB) structures. The method is first validated by checking with the analytic solution for the bistability characteristics of a strictly periodic, uniform NLDFB structure as well as the reported transmission characteristics of linear structures based on transfer matrix method calculation. The method is then applied to determine the transmission bistability characteristics of linearly tapered and linearly chirped NLDFB structures. The results are found to be different in some cases from those based on a generalized transfer matrix calculation in which the nonuniform structure is approximated by a set of strictly periodic, uniform segments.