Fresnel equation studies of longitudinally varying semiconductor rib waveguides: reference wavevector dependence

Abstract

We demonstrate that the accuracy of paraxial loss calculations for longitudinally varying semiconductor rib waveguides is significantly affected by the value assumed for the reference refractive index, n0. We then perform a full threedimensional simulation of a weakly guiding single-mode rib waveguide Y-junction, and compare our results to those of the effective index method, obtaining excellent agreement when n0 nearly coincides with the refractive index of the guided mode.