Direct numerical analysis of dual-mode elliptical-core optical fibers

A direct solution of the scalar wave equation (SWE) for an elliptical-core weakly guiding fiber is considered. We decompose the SWE into two ordinary differential equations by using the method of separation of variables, demand the periodicity of the solution in terms of the angular coordinate, and, by matching the boundary conditions numerically, obtain the characteristic propagation curves for the two modes. A simple computer program permits the acquisition of two-mode fiber device parameters as functions of the core ellipticity, the core dimensions, and the refractive-index difference.