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Proceedings Paper

Sagnac interferometer based stable phase demodulation system for diaphragm based acoustic sensor
Author(s): Jun Ma; Yongqin Yu; Wei Jin
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Paper Abstract

A modified fiber-optic Sagnac interferometer with a stable π/2 phase bias is demonstrated for the demodulation of diaphragm-based acoustic sensors. The phase bias is obtained by introducing a nonreciprocal frequency shift between the counter-propagating waves. The system is passive and without complicated servo-control for phase stabilization. Interrogated by the proposed demodulation system, a 100 nm-thick graphite diaphragm-based acoustic sensor demonstrated a minimum detectable pressure level of ~ 450 μPa/Hz1/2 at the frequency of 5 kHz and the output signal stability is less than 0.35 dB over an 8-hour period.

Paper Details

Date Published: 1 July 2015
PDF: 4 pages
Proc. SPIE 9655, Fifth Asia-Pacific Optical Sensors Conference, 96550D (1 July 2015); doi: 10.1117/12.2184271
Show Author Affiliations
Jun Ma, The Hong Kong Polytechnic Univ. (Hong Kong, China)
Yongqin Yu, Shenzhen Univ. (China)
Wei Jin, The Hong Kong Polytechnic Univ. (Hong Kong, China)


Published in SPIE Proceedings Vol. 9655:
Fifth Asia-Pacific Optical Sensors Conference
Byoungho Lee; Sang-Bae Lee; Yunjiang Rao, Editor(s)

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