Design of a Liquid Crystal Tunable Directional Coupler

The accurate analysis of optical waveguides is an important issue when designing devices for optical communication purposes. Different numerical approaches exist for modeling waveguide structures and one of the most important issues is the calculation of the guided modes of the waveguide. Commercial programs are widely available for the analysis of isotropic waveguides or waveguides with a reduced anisotropy. However, when using a waveguide that includes liquid crystals the anisotropy is general and nonuniform over the waveguide cross-section. For this reason we have developed a mode-solver that can handle fully anisotropic waveguides. The method is based on finite elements and uses higher order edge-elements in order to avoid spurious modes in the eigenvalue calculation [1]. This program is used in conjunction with a two-dimensional calculation of the liquid crystal orientation [2]. This latter calculation is based on a variable order Q-tensor method and can accurately simulate the liquid crystal orientation in arbitrary geometries, including the generation of defects within the liquid crystal.