Propagation in Asymmetrical Anisotropic Film Waveguides

Abstract

This paper considers a zig-zag wave analysis of three-layered biaxially anisotropic film waveguides with one of the principal axes of the crystal in the direction of propagation in each of the three media and other two parallel and perpendicular to the plane of the film. It provides an exact solution for the cutoff condition and approximate analytical expressions for the propagation constant, both near and far from cutoff. These approximations describe the propagation constant with sufficient accuracy even when the approximate components of the refractive index differ by as much as 10%. Several numerical examples illustrate the usefulness of the approximate relations. Graphical plots for the case of LiNbO(3) film waveguides on LiTaO(3) substrate are included.