Dispersion characteristics of strip dielectric waveguides

A simple and accurate dispersion relation is derived for the guided mode of a strip dielectric waveguide. This relation shows explicitly the effect of the width of the waveguide and involves only the solution for a single three-layer slab waveguide. It is found that there always exist a strip waveguide with a specific aspect ratio in which the E_mn^x and E_mn^y modes propagate at the same phase velocity