An iterative transfer matrix inverse scattering technique for the synthesis of co-directional optical couplers and filters

In this paper, we present a numerical iterative transfer matrix inverse scattering method for synthesizing coupling functions of co-directional couplers with prescribed response functions. The method is based on expanding a correction to a reference coupling function into a set of linearly independent basis functions. In each iteration step, the expansion coefficients are obtained by solving a direct scattering problem and then an inverse scattering problem. The method exhibits good agreement with the prescribed response functions.