Propagation properties of single-mode dielectric waveguide structures: a path integral approach.

A simple and efficient numerical method for the calculation of the fundamental and first-order mode propagation properties of single-mode waveguide structures with arbitrarily graded refractive-index profiles is presented. The method is based on a path integral treatment of the propagation equation of paraxial optics. The accuracy of the method and its potential for use in waveguide-structure design and characterization are illustrated by calculating the propagation constant for the fundamental and first-order modes of a graded-index slab waveguide, the intensity distribution of the fundamental mode of a graded-index slab waveguide, and by calculating the coupling length of a graded-index slab directional coupler as a function of fabrication-related variables.