Silicon anti-resonant reflecting optical waveguides for sensor applications

We review the design and fabrication considerations of silicon integrated optical (IO) waveguides and present a variety of device structures, for detection of mechanical signals, along with structures for coupling light to integrated photodetectors. These devices are based on the antiresonant reflecting optical waveguide (ARROW). The ARROW utilizes dielectric materials that are fully compatible with the standard integrated circuit (IC) and micromachining technologies. For optimization of IO pressure sensors, analysis and simulation of optomechanical effects including both the photoelastic effect and optical path length extension are performed. Exploiting the spatial and directional variation of stress in the waveguide on a micromachined diaphragm, we present relevant design considerations and measurement results of a push-pull micromechanical Mach-Zehnder interferometer (MZI) and demonstrate how ambiguities in pressure detection can be alleviated by suitable design of diaphragm geometries. By exploiting the intrinsic features of the ARROW, various IC-compatible structures for efficient coupling of waveguide to photodetector are proposed and fabricated. (C) 1998 Elsevier Science S.A.