{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,27]],"date-time":"2026-02-27T15:18:30Z","timestamp":1772205510092,"version":"3.50.1"},"reference-count":25,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2023,5,11]],"date-time":"2023-05-11T00:00:00Z","timestamp":1683763200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Natural Sciences Foundation of China","award":["62275269"],"award-info":[{"award-number":["62275269"]}]},{"name":"National Natural Sciences Foundation of China","award":["2022JCC014"],"award-info":[{"award-number":["2022JCC014"]}]},{"name":"National Natural Sciences Foundation of China","award":["2020GXNSFAA297173"],"award-info":[{"award-number":["2020GXNSFAA297173"]}]},{"name":"Interdisciplinary Scientific Research Foundation of Guangxi University","award":["62275269"],"award-info":[{"award-number":["62275269"]}]},{"name":"Interdisciplinary Scientific Research Foundation of Guangxi University","award":["2022JCC014"],"award-info":[{"award-number":["2022JCC014"]}]},{"name":"Interdisciplinary Scientific Research Foundation of Guangxi University","award":["2020GXNSFAA297173"],"award-info":[{"award-number":["2020GXNSFAA297173"]}]},{"name":"Natural Science Foundation of Guangxi","award":["62275269"],"award-info":[{"award-number":["62275269"]}]},{"name":"Natural Science Foundation of Guangxi","award":["2022JCC014"],"award-info":[{"award-number":["2022JCC014"]}]},{"name":"Natural Science Foundation of Guangxi","award":["2020GXNSFAA297173"],"award-info":[{"award-number":["2020GXNSFAA297173"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In the process of ocean exploration, highly accurate and sensitive measurements of seawater temperature and pressure significantly impact the study of seawater\u2019s physical, chemical, and biological processes. In this paper, three different package structures, V-shape, square-shape, and semicircle-shape, are designed and fabricated, and an optical microfiber coupler combined Sagnac loop (OMCSL) is encapsulated in these structures with polydimethylsiloxane (PDMS). Then, the temperature and pressure response characteristics of the OMCSL, under different package structures, are analyzed by simulation and experiment. The experimental results show that structural change hardly affects temperature sensitivity, and square-shape has the highest pressure sensitivity. In addition, with an input error of 1% F.S., temperature and pressure errors were calculated, which shows that a semicircle-shape structure can increase the angle between lines in the sensitivity matrix method (SMM), and reduce the effect of the input error, thus optimizing the ill-conditioned matrix. Finally, this paper shows that using the machine learning method (MLM) effectively improves demodulation accuracy. In conclusion, this paper proposes to optimize the ill-conditioned matrix problem in SMM demodulation by improving sensitivity with structural optimization, which essentially explains the cause of the large errors for multiparameter cross-sensitivity. In addition, this paper proposes to use the MLM to solve the problem of large errors in the SMM, which provides a new method to solve the problem of the ill-conditioned matrix in SMM demodulation. These have practical implications for engineering an all-optical sensor that can be used for detection in the ocean environment.<\/jats:p>","DOI":"10.3390\/s23104655","type":"journal-article","created":{"date-parts":[[2023,5,11]],"date-time":"2023-05-11T04:29:01Z","timestamp":1683779341000},"page":"4655","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Design of OMC-Sagnac Loop Using PDMS and Different Package Structures to Improve Sensing Performance and Optimize the Ill-Conditioned Matrix"],"prefix":"10.3390","volume":"23","author":[{"given":"Shumao","family":"Zhang","sequence":"first","affiliation":[{"name":"Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, School of Computer, Electronics and Information, Guangxi University, Nanning 530004, China"},{"name":"College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China"},{"name":"College of Sciences, National University of Defense Technology, Changsha 410073, China"},{"name":"College of Meteorology and Oceanography, National University of Defense Technology, Changsha 410073, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yang","family":"Yu","sequence":"additional","affiliation":[{"name":"College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China"},{"name":"College of Sciences, National University of Defense Technology, Changsha 410073, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5427-4475","authenticated-orcid":false,"given":"Xiaoyang","family":"Hu","sequence":"additional","affiliation":[{"name":"College of Meteorology and Oceanography, National University of Defense Technology, Changsha 410073, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2293-4467","authenticated-orcid":false,"given":"Qiang","family":"Bian","sequence":"additional","affiliation":[{"name":"College of Meteorology and Oceanography, National University of Defense Technology, Changsha 410073, China"},{"name":"Institute for Measurement Systems and Sensor Technology, Technical University of Munich, 80333 Munich, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dongying","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Meteorology and Oceanography, National University of Defense Technology, Changsha 410073, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Junjie","family":"Weng","sequence":"additional","affiliation":[{"name":"Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, School of Computer, Electronics and Information, Guangxi University, Nanning 530004, China"},{"name":"College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jianqiao","family":"Liang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, School of Computer, Electronics and Information, Guangxi University, Nanning 530004, China"},{"name":"College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-6704-7340","authenticated-orcid":false,"given":"Linyi","family":"Wei","sequence":"additional","affiliation":[{"name":"Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, School of Computer, Electronics and Information, Guangxi University, Nanning 530004, China"},{"name":"College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peng","family":"Jiang","sequence":"additional","affiliation":[{"name":"Changsha Sensintel Information Technology Co., Ltd., Changsha 410201, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hong","family":"Luo","sequence":"additional","affiliation":[{"name":"Changsha Sensintel Information Technology Co., Ltd., Changsha 410201, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9854-3529","authenticated-orcid":false,"given":"Linfeng","family":"Yang","sequence":"additional","affiliation":[{"name":"Guangxi Key Laboratory of Multimedia Communications and Network Technology, Guangxi University, Nanning 530004, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Junbo","family":"Yang","sequence":"additional","affiliation":[{"name":"College of Sciences, National University of Defense Technology, Changsha 410073, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1125-6637","authenticated-orcid":false,"given":"Zhenrong","family":"Zhang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, School of Computer, Electronics and Information, Guangxi University, Nanning 530004, China"},{"name":"Guangxi Key Laboratory of Multimedia Communications and Network Technology, Guangxi University, Nanning 530004, China"},{"name":"Guangxi Key Laboratory of Disaster Prevention and Engineering Safety, Guangxi University, Nanning 530004, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,5,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Zhou, L., Yu, Y., Huang, H., Tao, Y., Wen, K., Li, G., Yang, J., and Zhang, Z. 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