{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:18:54Z","timestamp":1760242734688,"version":"build-2065373602"},"reference-count":29,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2016,5,11]],"date-time":"2016-05-11T00:00:00Z","timestamp":1462924800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["61307075"],"award-info":[{"award-number":["61307075"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100013286","name":"Specialized Research Fund for the Doctoral Program of Higher Education of China","doi-asserted-by":"publisher","award":["20120142120067"],"award-info":[{"award-number":["20120142120067"]}],"id":[{"id":"10.13039\/501100013286","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012226","name":"Fundamental Research Funds for the Central Universities","doi-asserted-by":"publisher","award":["HUST:2014TS019"],"award-info":[{"award-number":["HUST:2014TS019"]}],"id":[{"id":"10.13039\/501100012226","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Director Fund of Wuhan National Laboratory for Optoelectronics"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A highly sensitive refractive index sensor with low detection limit based on an asymmetric optical microfiber coupler is proposed. It is composed of a silica optical microfiber and an As2Se3 optical microfiber. Due to the asymmetry of the microfiber materials, a single-notch transmission spectrum is demonstrated by the large refractive index difference between the two optical microfibers. Compared with the symmetric coupler, the bandwidth of the asymmetric structure is over one order of magnitude narrower than that of the former. Therefore, the asymmetric optical microfiber coupler based sensor can reach over one order of magnitude smaller detection limit, which is defined as the minimal detectable refractive index change caused by the surrounding analyte. With the advantage of large evanescent field, the results also show that a sensitivity of up to 3212 nm per refractive index unit with a bandwidth of 12 nm is achieved with the asymmetric optical microfiber coupler. Furthermore, a maximum sensitivity of 4549 nm per refractive index unit can be reached while the radii of the silica optical microfiber and As2Se3 optical microfiber are 0.5 \u03bcm and a 0.128 \u03bcm, respectively. This sensor component may have important potential for low detection-limit physical and biochemical sensing applications.<\/jats:p>","DOI":"10.3390\/s16050672","type":"journal-article","created":{"date-parts":[[2016,5,11]],"date-time":"2016-05-11T04:38:53Z","timestamp":1462941533000},"page":"672","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Modeling of a Single-Notch Microfiber Coupler for High-Sensitivity and Low Detection-Limit Refractive Index Sensing"],"prefix":"10.3390","volume":"16","author":[{"given":"Jiali","family":"Zhang","sequence":"first","affiliation":[{"name":"Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lei","family":"Shi","sequence":"additional","affiliation":[{"name":"Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Song","family":"Zhu","sequence":"additional","affiliation":[{"name":"Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xinbiao","family":"Xu","sequence":"additional","affiliation":[{"name":"Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xinliang","family":"Zhang","sequence":"additional","affiliation":[{"name":"Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2016,5,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"816","DOI":"10.1038\/nature02193","article-title":"Subwavelength-diameter silica wires for low-loss optical wave guiding","volume":"426","author":"Tong","year":"2003","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1016\/j.aca.2008.05.022","article-title":"Sensitive optical biosensors for unlabeled targets: A review","volume":"620","author":"Fan","year":"2008","journal-title":"Anal. 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