MODAL CUTOFF CONDITIONS OF A HYPOCYCLOIDAL WAVE-GUIDE WITH VARIOUS TYPES OF METAL LOADING ON THE CORE BOUNDARIES

Goell's point-matching technique under weak guidance is used to study the modal cutoff conditions of a waveguide with a hypocycloidal cross section in two cases. It is seen that, for an alternate-sides metal-lo aded hypocycloidal waveguide (AMLH), there is an increase in the total number of modes with lower cutoff values as the aspect ratio (the rat io of two orthogonal dimensions) is inn eased. When the waveguide is m etal loaded on three sides out of four. (TMLH), the number of modes in creases significantly with an increase of the aspect ratio. The TMLH w aveguide supports more modes than the AMLH waveguide for all aspect ra tios. (C) 1998 John Wiley & Sons, Inc.