Modal cutoff condition for an optical waveguide with a hypocycloidal cross section

The characteristic equation for an optical waveguide with a hypocycloidal cross section is obtained. This cross section can be thought of as having the shape of a distorted square and leads to a tolerance analysis for deformation in a square waveguide. The complex geometry makes the analysis of modes difficult. With some simplifications the cutoff condition under the weak-guidance condition is obtained. A brief comparison is then made with the cutoff condition for the conventional fiber and also that of a waveguide with a square cross section. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 14, 177–180, 1997