Modal cutoff conditions of a hypocycloidal waveguide with various types of metal loading on the core boundaries

Abstract

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-loaded hypocycloidal waveguide (AMLH), there is an increase in the total number of modes with lower cutoff values as the aspect ratio (the ratio of two orthogonal dimensions) is increased. When the waveguide is metal loaded on three sides out of four (TMLH), the number of modes increases significantly with an increase of the aspect ratio. The TMLH waveguide supports more modes than the AMLH waveguide for all aspect ratios. © 1998 John Wiley & Sons, Inc.