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

Demonstrates 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. The authors then perform a full three-dimensional simulation of a weakly guiding single-mode rib waveguide Y-junction, and compare results to those of the effective index method obtaining excellent agreement when n₀ nearly coincides with the refractive index of the guided mode.