Integrated optical interferometer with micromechanical diaphragm for pressure sensing

An electrically passive optical pressure sensor has been fabricated which uses a integrated-optical Y-junction ring resonator to measure the strain induced in a micromachined silicon diaphragm. A silicon substrate is etched from the side opposite the silicon oxynitride optical waveguides to produce a rectangular diaphragm whose long edge lies underneath a straight section in the ring. Pressure-induced changes in the resonant frequency of the ring are measured using a frequency swept laser diode. A linear response to pressure is observed for the TM mode with a sensitivity of 0.0094 rad/kPa. The transmissivity function of the resonator is derived and compared with measured response. This pressure sensor is rugged, amenable to batch fabrication, and it provides a link insensitive readout.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.