{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T02:49:56Z","timestamp":1774579796441,"version":"3.50.1"},"reference-count":20,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2023,5,22]],"date-time":"2023-05-22T00:00:00Z","timestamp":1684713600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"project of outstanding young and middle-aged science and technology innovation teams of colleges and universities","award":["T201907"],"award-info":[{"award-number":["T201907"]}]},{"name":"project of outstanding young and middle-aged science and technology innovation teams of colleges and universities","award":["2021EHB018"],"award-info":[{"award-number":["2021EHB018"]}]},{"name":"International Science and Technology Cooperation Key Research and Development Program of Science and Technology Agency in Hubei Province","award":["T201907"],"award-info":[{"award-number":["T201907"]}]},{"name":"International Science and Technology Cooperation Key Research and Development Program of Science and Technology Agency in Hubei Province","award":["2021EHB018"],"award-info":[{"award-number":["2021EHB018"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper presents a novel improvement in the optical path structure of a three-wavelength symmetric demodulation method applied to extrinsic Fabry\u2013Perot interferometer (EFPI) fiber optic acoustic sensors. The traditional approach of using couplers to construct the phase difference in the symmetric demodulation method is replaced with a new approach that combines the symmetric demodulation algorithm with wavelength division multiplexing (WDM) technology. This improvement addresses the issue of a suboptimal coupler split ratio and phase difference, which can affect the accuracy and performance of the symmetric demodulation method. In an anechoic chamber test environment, the symmetric demodulation algorithm implemented with the WDM optical path structure achieved a signal-to-noise ratio (SNR) of 75.5 dB (1 kHz), a sensitivity of 1104.9 mV\/Pa (1 kHz), and a linear fitting coefficient of 0.9946. In contrast, the symmetric demodulation algorithm implemented with the traditional coupler-based optical path structure achieved an SNR of 65.1 dB (1 kHz), a sensitivity of 891.75 mV\/Pa (1 kHz), and a linear fitting coefficient of 0.9905. The test results clearly indicate that the improved optical path structure based on WDM technology outperforms the traditional coupler-based optical path structure in terms of sensitivity, SNR, and linearity.<\/jats:p>","DOI":"10.3390\/s23104985","type":"journal-article","created":{"date-parts":[[2023,5,23]],"date-time":"2023-05-23T02:02:27Z","timestamp":1684807347000},"page":"4985","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Improved Optical Path Structure for Symmetric Demodulation Method in EFPI Fiber Optic Acoustic Sensors Using Wavelength Division Multiplexing"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-2764-8044","authenticated-orcid":false,"given":"Hao","family":"Chen","sequence":"first","affiliation":[{"name":"School of Science, Hubei University of Technology, Wuhan 430068, China"},{"name":"Hubei Engineering Technology Research Center of Energy Photoelectric Device and System, Hubei University of Technology, Wuhan 430068, China"}]},{"given":"Chenggang","family":"Guan","sequence":"additional","affiliation":[{"name":"School of Science, Hubei University of Technology, Wuhan 430068, China"},{"name":"Hubei Engineering Technology Research Center of Energy Photoelectric Device and System, Hubei University of Technology, Wuhan 430068, China"}]},{"given":"Hui","family":"Lv","sequence":"additional","affiliation":[{"name":"School of Science, Hubei University of Technology, Wuhan 430068, China"},{"name":"Hubei Engineering Technology Research Center of Energy Photoelectric Device and System, Hubei University of Technology, Wuhan 430068, China"}]},{"given":"Can","family":"Guo","sequence":"additional","affiliation":[{"name":"School of Science, Hubei University of Technology, Wuhan 430068, China"},{"name":"Hubei Engineering Technology Research Center of Energy Photoelectric Device and System, Hubei University of Technology, Wuhan 430068, China"}]},{"given":"Shiyi","family":"Chai","sequence":"additional","affiliation":[{"name":"School of Science, Hubei University of Technology, Wuhan 430068, China"},{"name":"Hubei Engineering Technology Research Center of Energy Photoelectric Device and System, Hubei University of Technology, Wuhan 430068, China"}]}],"member":"1968","published-online":{"date-parts":[[2023,5,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1761","DOI":"10.1364\/AO.16.001761","article-title":"Optical fiber acoustic sensor","volume":"16","author":"Bucaro","year":"1977","journal-title":"Appl. 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