Demodulation of diaphragm based acoustic sensor using Sagnac interferometer with stable phase bias

Jun Ma, Yongqin Yu, Wei Jin

Research output: Journal article publicationJournal articleAcademic researchpeer-review

59 Citations (Scopus)


A stable phase demodulation system for diaphragm-based acoustic sensors is reported. The system is based on a modified fiber-optic Sagnac interferometer with a stable quadrature phase bias, which is independent of the parameters of the sensor head. The phase bias is achieved passively by introducing a nonreciprocal frequency shift between the counter-propagating waves, avoiding the use of complicated active servo-control. A 100 nm-thick graphite diaphragm-based acoustic sensor interrogated by the proposed demodulation system demonstrated a minimum detectable pressure level of ~450 μPa/Hz1/2 and an output signal stability of less than 0.35 dB over an 8-hour period. The system may be useful as a universal phase demodulation unit for diaphragm-based acoustic sensors as well as other sensors operating in a reflection mode.
Original languageEnglish
Pages (from-to)29268-29278
Number of pages11
JournalOptics Express
Issue number22
Publication statusPublished - 2 Nov 2015

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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