A new class of environmental parameter sensors, which operate by the direct interaction between low levels of optical energy and very small coated beams of silicon dioxide, is being developed. The beams are fabricated using well-established silicon micromachining techniques and, in general, have lengths of the order of 100 microns and a cross-section of 5 microns by 1 micron. Optical power levels in the region of microwatts focussed onto the coated surface of these beams can set them into vibration at frequencies of hundreds of kiloHertz with amplitudes of a few nanometres. Such vibrations can easily be detected by optical interferometric techniques, using either a separate optical source as a probe, or even the same source used to initiate the vibrations. If such a beam is interfaced appropriately to an environmentally sensitive element, such as a diaphragm for pressure measurements, or a selectively absorbing film for chemical measurements, its mechanical resonant frequency is correspondingly altered. This frequency change can then be determined by the optical detection system, resulting in an elegant all-optical microsensor.

Date Published: 3 January 1986
PDF: 4 pages
Proc. SPIE 0566, Fiber Optic and Laser Sensors III, (3 January 1986); doi: 10.1117/12.949773

Published in SPIE Proceedings Vol. 0566:
Fiber Optic and Laser Sensors III
Emery L. Moore; O. Glenn Ramer, Editor(s)