Modal characteristics of an annular waveguide of constant radial width having elliptical boundaries

Abstract

We consider an annular elliptic lightguide of constant radial width (CRWEG), whose guiding region cross section is bounded by two elliptical boundaries. Using Goell's point-matching method, we obtain the characteristic equation and dispersion curves for this wave-guide. When the dispersion curves of this waveguide are compared with that of confocal and concentric elliptic lightguides (CFEG and CEG), it is found that they are less steep for CRWEG. It is also found that the cutoff value of the lowest order modes for this waveguide is greater than that for CFEG and CEG. This means that this waveguide supports fewer modes than CFEG and CEG.