{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,16]],"date-time":"2026-02-16T08:42:25Z","timestamp":1771231345071,"version":"3.50.1"},"reference-count":59,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2014,6,20]],"date-time":"2014-06-20T00:00:00Z","timestamp":1403222400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Fiber-optic sensing is a field that is developing at a fast pace. Novel fiber-optic sensor designs and sensing principles constantly open doors for new opportunities. In this paper, we review a fiber-optic sensing technique developed in our research group called frequency-shifted interferometry (FSI). This technique uses a continuous-wave light source, an optical frequency shifter, and a slow detector. We discuss the operation principles of several FSI implementations and show their applications in fiber length and dispersion measurement, locating weak reflections along a fiber link, fiber-optic sensor multiplexing, and high-sensitivity cavity ring-down measurement. Detailed analysis of FSI system parameters is also presented.<\/jats:p>","DOI":"10.3390\/s140610977","type":"journal-article","created":{"date-parts":[[2014,6,20]],"date-time":"2014-06-20T11:34:08Z","timestamp":1403264048000},"page":"10977-11000","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Frequency-Shifted Interferometry \u2014 A Versatile Fiber-Optic Sensing Technique"],"prefix":"10.3390","volume":"14","author":[{"given":"Fei","family":"Ye","sequence":"first","affiliation":[{"name":"The Edward S. Rogers Sr. Department of Electrical and Computer Engineering,  University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yiwei","family":"Zhang","sequence":"additional","affiliation":[{"name":"The Edward S. Rogers Sr. Department of Electrical and Computer Engineering,  University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bing","family":"Qi","sequence":"additional","affiliation":[{"name":"Quantum Information Science Group, Oak Ridge National Laboratory, 1 Bethel Valley Road,  Oak Ridge, TN 37830, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Li","family":"Qian","sequence":"additional","affiliation":[{"name":"The Edward S. Rogers Sr. Department of Electrical and Computer Engineering,  University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2014,6,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1064","DOI":"10.1109\/JLT.0082.921915","article-title":"Fiber-optic sensing: A historical perspective","volume":"26","author":"Culshaw","year":"2008","journal-title":"J. Light. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1109\/JLT.2003.822139","article-title":"Optical fiber sensor technologies: Opportunities and\u2013perhaps\u2013pitfalls","volume":"22","author":"Culshaw","year":"2004","journal-title":"J. Light. 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