Open Access
Optics Express, volume 28, issue 17, pages 25238
High sensitivity fiber-optic Michelson interferometric low-frequency acoustic sensor based on a gold diaphragm
Pingjie Fan
1
,
Wei Yan
2
,
Ping Lu
1
,
Wanjin Zhang
2
,
Wei Zhang
1
,
Xin Fu
1
,
Jiangshan Zhang
1
2
These authors contribute equally to this paper
Publication type: Journal Article
Publication date: 2020-08-11
PubMed ID:
32907049
Atomic and Molecular Physics, and Optics
Abstract
A Michelson interferometric fiber-optic acoustic sensor based on a large-area gold diaphragm is proposed in this paper. The Michelson interferometer (MI) based on 3×3 coupler is comprised of two beams that reflected from the gold diaphragm and a cleaved fiber end face. Thickness and diameter of the gold diaphragm are 300 nm and 2.5 mm, respectively. Based on the phase difference between each output port of the 3×3 fiber coupler, an ellipse fitting differential cross multiplication (EF-DCM) interrogation process is induced for phase demodulation, which can overcome the phase distortion caused by property degradation of 3×3 coupler. Experimental results show that the sensor has a phase sensitivity of about -130.6 dB re 1 rad/μPa@100 Hz. A flat response range between 0.8 to 250 Hz is realized with the sensitivity fluctuation below 0.7 dB. Besides, the signal-to-noise ratio (SNR) and minimal detectable pressure (MDP) of the sensor are 57.9 dB and 10.2 mPa/Hz1/2 at 5 Hz. The proposed sensor exhibits superiorities of compact size, high sensitivity, flat low-frequency response and ease of mass production, which gives the sensor great potential for low-frequency acoustic sensing and photo-acoustic spectroscopy.
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