New low-loss bend structures for high-density integrated optical switch arrays

A technique for lowering the loss around discrete bends in weakly guiding integrated optical circuits proposed, and modeling based on the beam-propagation method predicts a large improvement in the bend losses when it is applied. The idea of inserting an outrigger waveguide of high-refractive index appears to be novel, is relatively easily implemented practically, and shows considerable potential. The development of this idea is an excellent example of the use of numerical CAD (computer-aided design) tools in device design, since it is unlikely that it would have been discovered by experimentation alone. A CAD package for running the BPM (BEAMER) has been used to iterate towards low-loss bend geometries