A Finite-Difference Time-Domain Method for the Design and Analysis of Guided-Wave Optical Structures

A CAD tool employing the finite-difference time-domain (FDTD) algorithm is developed for the design and analysis of optical waveguide structures. The basic formulation of the algorithm is given, and the set of practical conditions for the application is briefly outlined. The accuracy of the numerical scheme is investigated through a study of a canonical parallel-slabs coupling structure. Both the coupling length and the field distribution are in good agreement with results in the literature. The use of the method is illustrated by an analysis of a typical optical component: a directional coupler. We expect the method to be a powerful tool in the analysis of optical structures, especially for structures with large discontinuities.