A Bi-Boundary FEM-BEM Approach for Open Structure Optical Waveguide Problems

A bi-boundary finite element method (FEM)-boundary element method (BEM) approach that can accelerate the analysis of the nonsymmetrical matrix equations obtained by the hybrid FEM-BEM for optical waveguides is presented. An extra auxiliary boundary is adopted to separate the large order nonsymmetrical matrix into a small order nonsymmetrical part and a large order sparse symmetrical part. Subsequently, an iterative solution is introduced to incorporate the two parts. The efficiency of the approach is nearly 2.5 times faster than that of the conventional hybrid FEM-BEM system.