{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:28:54Z","timestamp":1760236134483,"version":"build-2065373602"},"reference-count":49,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2021,10,29]],"date-time":"2021-10-29T00:00:00Z","timestamp":1635465600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"FCT-Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","award":["UIDB\/50014\/2020"],"award-info":[{"award-number":["UIDB\/50014\/2020"]}]},{"name":"proMetheus\u2014Research Unit on Materials, Energy and Environment for Sustainability","award":["UID\/05975\/2020"],"award-info":[{"award-number":["UID\/05975\/2020"]}]},{"name":"Russian Ministry of Higher Education and Science","award":["075-15-2021-581"],"award-info":[{"award-number":["075-15-2021-581"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this paper, we investigate modification of transmission spectra of long-period fiber grating structures with an acoustic shock front propagating along the fiber. We simulate transmission through inhomogeneous long-period fiber gratings, \u03c0-shift and reflective \u03c0-shift gratings deformed by an acoustic shock front. Coupled mode equations describing interaction of co-propagating modes in a long-period fiber grating structures with inhomogeneous deformation are used for the simulation. Two types of apodization are considered for the grating modulation amplitude, such as uniform and raised-cosine. We demonstrate how the transmission spectrum is produced by interference between the core and cladding modes coupled at several parts of the gratings having different periods. For the \u03c0-shift long-period fiber grating having split spectral notch, the gap between the two dips becomes several times wider in the grating with the acoustic wave front than the gap in the unstrained grating. The behavior of reflective long-period fiber gratings depends on the magnitude of the phase shift near the reflective surface: an additional dip is formed in the 0-shift grating and the short-wavelength dip disappears in the \u03c0-shift grating.<\/jats:p>","DOI":"10.3390\/s21217212","type":"journal-article","created":{"date-parts":[[2021,11,1]],"date-time":"2021-11-01T22:24:22Z","timestamp":1635805462000},"page":"7212","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Simulation of the Transmission Spectrum of Long-Period Fiber Gratings Structures with a Propagating Acoustic Shock Front"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4443-7514","authenticated-orcid":false,"given":"Oleg V.","family":"Ivanov","sequence":"first","affiliation":[{"name":"Ulyanovsk Branch of Kotel\u2019nikov Institute of Radio Engineering and Electronics of Russian Academy of Sciences, Ulitsa Goncharova 48, 432071 Ulyanovsk, Russia"},{"name":"Ulyanovsk State University, S.P. Kapitsa Research Institute of Technology, Ulitsa L. Tolstogo 42, 432017 Ulyanovsk, Russia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3223-9783","authenticated-orcid":false,"given":"Paulo","family":"Caldas","sequence":"additional","affiliation":[{"name":"ProMetheus-Research Unit in Materials, Energy and Environment for Sustainability, Instituto Polit\u00e9cnico de Viana do Castelo, 4900-347 Viana do Castelo, Portugal"},{"name":"Center for Applied Photonics, Institute for Systems and Computer Engineering, Technology and Science (INESC TEC), Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8807-4108","authenticated-orcid":false,"given":"Gaspar","family":"Rego","sequence":"additional","affiliation":[{"name":"ProMetheus-Research Unit in Materials, Energy and Environment for Sustainability, Instituto Polit\u00e9cnico de Viana do Castelo, 4900-347 Viana do Castelo, Portugal"},{"name":"Center for Applied Photonics, Institute for Systems and Computer Engineering, Technology and Science (INESC TEC), Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,10,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Kashyap, R. 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