PERFORMANCE COMPARISON OF FINITE-ELEMENT APPROACHES FOR ELECTROMAGNETIC WAVE-GUIDES

The accuracy of finite-element-method techniques used for waveguide mo dal analysis has usually been assessed by testing the precision of the propagation constant. As a consequence, no useful criteria have been proposed for checking the spatial distribution of the evaluated unknow n field. To overcome this lack, two error figures have been introduced and applied to different finite-element-method formulations. In parti cular, the following approaches have been compared: the one based on t he transverse magnetic field, those based on the so-called edge elemen ts, and a new one presented by the authors. The new approach, obtained by simply operating on the matrices of the original node-based formul ation, directly solves for the propagation constant at a given frequen cy, preserves the matrix sparsity, and directly evaluates all of the u nknown magnetic field components. Results demonstrate the applicabilit y of the proposed approach and the usefulness of the introduced figure s for a deep waveguide analysis. (C) 1997 Optical Society of America.