Abstract

We discuss various numerical techniques for evaluating electric fields in strongly guiding rib-waveguide structures. We first demonstrate that the matrix beam propagation algorithm can be efficiently adapted to modal analysis in a form in which only a few field distributions are evolved in imaginary longitudinal distance. Subsequently, we consider longitudinally varying rib-waveguide elements. We introduce and compare the split-step fast-Fourier-transform, modified split-step fast-Fourier-trans form, split-operator finite-difference, real-space, and split-operator finite-element methods for solving the Fresnel equation. The predicted losses are in good agreement with both experimental measurements on strongly guiding S bends and, in the weakly guiding limit, effective index studies of Y junctions. We further present an explicit illustration of component optimization by determining the power transmission of Y junctions of various geometries.

© 1990 Optical Society of America