Optimization and control of grating coupling to or from a silicon‐based optical waveguide

The analysis of a silicon-based step-index waveguide with a corrugation grating at its surface is performed by considering the reflec- tion between the silicon substrate and the optical buffer. The conditions on the silica buffer thickness for maximum in/out coupling into the sub- strate and into the air are given analytically, and a number of features of practical interest are described. © 1996 Society of Photo-Optical Instrumentation Engineers.