Method for calculating the properties of polarisation-maintaining 3D waveguides in very thin multilayered structures

We propose and analyse a new optical three-dimensional waveguide having the function of a single-mode polarisation-maintaining waveguide or TE/TM mode splitter. In the optical waveguide proposed a multilayer film composed of two dielectric materials with different refractive indices provides confinement in the height direction, and strong mode separation between TE- and TM-like modes, whilst a strip-loaded or rib-type structure provides confinement in the lateral direction. A full analysis of the structure based on a mode-matching method and a familiar equivalent circuit representation of 3D waveguides is presented. We also discuss several fundamental properties of the guided waves supported by the proposed waveguide for various structural parameters