Sagnac interferometer based stable phase demodulation system for diaphragm based acoustic sensor

Jun Ma; Yongqin Yu; Wei Jin

doi:10.1117/12.2184271

1 July 2015 Sagnac interferometer based stable phase demodulation system for diaphragm based acoustic sensor

Jun Ma, Yongqin Yu, Wei Jin

Proceedings Volume 9655, Fifth Asia-Pacific Optical Sensors Conference; 96550D (2015) https://doi.org/10.1117/12.2184271
Event: Fifth Asia Pacific Optical Sensors Conference, 2015, Jeju, Korea, Republic of

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/Hz^1/2at the frequency of 5 kHz and the output signal stability is less than 0.35 dB over an 8-hour period.

Citation Download Citation

Jun Ma, Yongqin Yu, and Wei Jin "Sagnac interferometer based stable phase demodulation system for diaphragm based acoustic sensor", Proc. SPIE 9655, Fifth Asia-Pacific Optical Sensors Conference, 96550D (1 July 2015); https://doi.org/10.1117/12.2184271

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