New Jersey Institute of Technology

Guanhua Feng

Ken K Chin

Harry Roman

Ivan Padron

The present invention is a diaphragm-fiber optic sensor (DFOS), interferometric sensor. This DFOS is based on the principles of Fabry-Perot and Michelson/Mach-Zehnder. The sensor is low cost and is designed with high efficiency, reliability, and Q-point stability, fabricated using MEMS (micro mechanic-electrical system) technology, and has demonstrated excellent performance. A DFOS according to the invention includes a cavity between two surfaces: a diaphragm made of silicon or other material with a rigid body (or boss) at the center and clamped along its edge, and the endface of a single mode optic fiber. By utilizing MEMS technology, the gap width between the diaphragm and the fiber endface is made accurately, ranging from 1 micron to 10 microns. To stabilize the Q-point of the DFOS when in use as an acoustic sensor, a system of microchannels is built in the structure of the diaphragm so that the pressure difference on two sides of the diaphragm is kept a constant, independent of the hydraulic pressure and/or low frequency noise when the device is inserted in liquid mediums.

Aligned embossed diaphragm based fiber optic sensor

The theory, design, fabrication, and characterization of MEMS (micro electrical mechanical system) Fabry-Perot diaphragm-fiber optic microphone are described in the present invention. By using MEMS technology in processing and packaging, a square 1.9 mm&#xd7;1.9 mm, 2 &#x3bc; thick SiOdiaphragm with a 350 &#x3bc; square embossed center of silicon is mechanically clamped to the ferrule of a single mode fiber to keep its closeness (5 &#x3bc;) and perpendicular orientation with respect to the diaphragm. Static measurement of optical output power versus the pressure on membrane reveals more than one period of Fabry-Perot interference, thereby generating a Fabry-Perot diaphragm-fiber interferometer device accurately reproducing audible acoustic wave.

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Dover, NJ, United States of America

Guanhua Feng