Abstract

We have found that the results of various 3-D numerical models based on the Fresnel equation for forward wave propagation in semiconductor rib waveguides depend considerably on the value chosen for the reference refractive index n₀. This constant should optimally not deviate greatly from the effective indices of the guided modes. To illustrate, we analyze a weakly confining Y-junction structure with a small rib height where excellent agreement between our 3-D calculations and the 2-D effective index method is attained only if n₀ is selected according to the above criterion. We then display the variation in the computed losses of strongly guiding Y-junctions with changes in n₀.

© 1989 Optical Society of America