Optimization of strongly guiding semiconductor rib waveguide Y-junctions

Abstract
The three-dimensional split-step fast Fourier transform beam propagation method is used to demonstrate that losses associated with a strongly guiding semiconductor rib waveguide Y-junction can be substantially reduced by adding an optimized length of an initial straight broad waveguide segment. It is shown that the resulting transmission is relatively insensitive to the exact waveguide dimensions and in particular to the geometry of the Y-junction vertex.