Fast numerical analysis of dielectric resonators with perturbed rotational symmetry

A fast finite difference frequency domain (FDFD) formulation for obtaining resonant frequencies of structures with perturbed rotational symmetry is described. The formulation combines a three-dimensional (3-D) eigenfunction function expansion algorithm with 3-D FDFD in the cylindrical coordinate system. Numerical tests have showed that the technique gives high accuracy results and significant CPU time reduction.