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.