Lightguides with core cross-section bounded by two spirals: Effect of curvature on dispersion curves

Recently Sing ct at. [1-2] investigated the dispersion characteristics and cutoff conditions of a wave guide whose guidng cross-section was assumed to be bounded by two spirals, r=ce-theta(2)/2 and r=be -theta(2)/2. In that p aper [2] the width (b - c) is allowed to change by changing the parameter b and keeping c fixed at 2.0 mu m. Here in this paper, we want to study how the dispersion characteristic change with curvature considering a few more fixed values of c. We choose c = 4.0 mu m and c = 6.0 mu m, so that the ave rage curvature may be less than curvature corresponding to c = 2.0 mu m. It is found that as the curvature of the guide decreases the number of sustai ned modes for a given value V shows a tendency to decrease.