A study of high-index-contrast 90 degrees waveguide bend structures

We present an evaluation of the parameters involved in designing low-loss r ight-angle waveguide bends based on a high index contrast materials system. We apply the finite difference time domain method (FDTD) to several two-di mensional bend structures and study the effects of varying the bend geometr y. Such a study is relevant for the understanding of bend mechanisms and fo r the optimization and fabrication of high-density high-contrast integrated optical components. The study indicates that high bend transmission can be achieved with the addition of a low-Q resonant cavity; however, similar or even better performance can be achieved with a structure that combines a c orner mirror with a phase retarder. The use of a double corner mirror struc ture is shown to further increase the bend transmission, with little increa se in bend area. (C) 2001 Optical Society of America.