{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T03:01:39Z","timestamp":1760151699649,"version":"build-2065373602"},"reference-count":24,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2022,4,12]],"date-time":"2022-04-12T00:00:00Z","timestamp":1649721600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>A new methodology to enhance the sensitivity of a long period fiber grating sensor (LPFG) at the Turn Around Point (TAP) is here presented. The LPFG sensor has been fabricated by etching the fiber up to 20.4 \u00b5m, until the sidelobes of dispersed LP0,2 cladding mode appeared near TAP in aqueous medium. The dual peak sensitivity of the sidelobes was found to be 16,044 nm\/SRIU (surrounding refractive index units) in the RI range from 1.333 to 1.3335.<\/jats:p>","DOI":"10.3390\/s22082965","type":"journal-article","created":{"date-parts":[[2022,4,12]],"date-time":"2022-04-12T22:48:45Z","timestamp":1649803725000},"page":"2965","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Sensitivity Analysis of Sidelobes of the Lowest Order Cladding Mode of Long Period Fiber Gratings at Turn Around Point"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2596-2025","authenticated-orcid":false,"given":"Tanoy Kumar","family":"Dey","sequence":"first","affiliation":[{"name":"Central Glass and Ceramic Research Institute, CSIR-CGCRI, 196 Raja S C Mullick Road, Kolkata 700032, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1660-9833","authenticated-orcid":false,"given":"Sara","family":"Tombelli","sequence":"additional","affiliation":[{"name":"Institute of Applied Physics \u201cNello Carrara\u201d, CNR-IFAC, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4899-496X","authenticated-orcid":false,"given":"Arpan","family":"Roy","sequence":"additional","affiliation":[{"name":"Central Glass and Ceramic Research Institute, CSIR-CGCRI, 196 Raja S C Mullick Road, Kolkata 700032, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Palas","family":"Biswas","sequence":"additional","affiliation":[{"name":"Central Glass and Ceramic Research Institute, CSIR-CGCRI, 196 Raja S C Mullick Road, Kolkata 700032, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0002-2977","authenticated-orcid":false,"given":"Ambra","family":"Giannetti","sequence":"additional","affiliation":[{"name":"Institute of Applied Physics \u201cNello Carrara\u201d, CNR-IFAC, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nandini","family":"Basumallick","sequence":"additional","affiliation":[{"name":"Central Glass and Ceramic Research Institute, CSIR-CGCRI, 196 Raja S C Mullick Road, Kolkata 700032, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2689-5952","authenticated-orcid":false,"given":"Francesco","family":"Baldini","sequence":"additional","affiliation":[{"name":"Institute of Applied Physics \u201cNello Carrara\u201d, CNR-IFAC, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Somnath","family":"Bandyopadhyay","sequence":"additional","affiliation":[{"name":"Central Glass and Ceramic Research Institute, CSIR-CGCRI, 196 Raja S C Mullick Road, Kolkata 700032, India"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7822-4459","authenticated-orcid":false,"given":"Cosimo","family":"Trono","sequence":"additional","affiliation":[{"name":"Institute of Applied Physics \u201cNello Carrara\u201d, CNR-IFAC, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,4,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"663","DOI":"10.1515\/nanoph-2016-0178","article-title":"Biosensing with optical fiber gratings","volume":"6","author":"Chiavaioli","year":"2017","journal-title":"Nanophotonics"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1016\/j.bios.2019.03.024","article-title":"Label-free detection of Staphylococcus aureus bacteria using long-period fiber grating with functional polyelectrolyte coatings","volume":"133","author":"Yang","year":"2019","journal-title":"Biosens. Bioelectron."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"223","DOI":"10.1016\/j.snb.2018.10.001","article-title":"Optical investigation of electrochemical process using a long-period fiber grating functionalized by indium tin oxide","volume":"279","author":"Burnat","year":"2019","journal-title":"Sens. Actuators B Chem."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1606","DOI":"10.1109\/50.712243","article-title":"Analysis of the response of long period fiber grating to external index of refraction","volume":"16","author":"Patrick","year":"1998","journal-title":"J. Lightwave Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1364\/OPEX.13.000056","article-title":"Optimization of sensitivity in long period fiber grating with overlay deposition","volume":"13","author":"Matias","year":"2005","journal-title":"Opt. Express"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"12024","DOI":"10.1021\/acs.analchem.5b01841","article-title":"Sol-gel-based titania-silica thin film overlay for long period fiber grating based biosensors","volume":"87","author":"Chiavaioli","year":"2015","journal-title":"Anal. Chem."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"20039","DOI":"10.1364\/OE.17.020039","article-title":"Long period grating working in transition mode as promising technological platform for label free biosensing","volume":"17","author":"Pilla","year":"2009","journal-title":"Opt. Express"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"512","DOI":"10.1364\/OE.19.000512","article-title":"Transition mode long period grating biosensor with functional multilayer coatings","volume":"19","author":"Pilla","year":"2011","journal-title":"Opt. Express"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1109\/50.983240","article-title":"Sensitivity characteristics of long-period fiber grating","volume":"20","author":"Shu","year":"2002","journal-title":"J. Lightwave Technol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1240","DOI":"10.1109\/JSEN.2014.2361166","article-title":"Sensitivity enhancement of turn-around-point long period grating by tuning initial coupling condition","volume":"15","author":"Biswas","year":"2015","journal-title":"IEEE Sens. J."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"966","DOI":"10.1049\/el:20000701","article-title":"Analysis of etched long-period fiber grating and its response to external refractive index","volume":"36","author":"Chiang","year":"2000","journal-title":"Electron. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"5986","DOI":"10.1364\/OE.22.005986","article-title":"Measurements of reactive ion etching process effect using long-period fiber gratings","volume":"22","author":"Koba","year":"2014","journal-title":"Opt. Express"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"4006","DOI":"10.1109\/JLT.2020.2987795","article-title":"Analysis of the lowest order cladding mode of long period fiber gratings near Turn Around Point","volume":"39","author":"Dey","year":"2021","journal-title":"J. Lightwave Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"889","DOI":"10.1109\/JLT.2019.2949373","article-title":"Optimization of refractive index sensitivity in nano-film coated long-period fiber grating near dispersion turning point","volume":"38","author":"Zou","year":"2019","journal-title":"J. Lightwave Technol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"17680","DOI":"10.1364\/OE.24.017680","article-title":"Sensitivity optimization with cladding-etched long period fiber gratings at dispersion turning point","volume":"24","author":"Cruz","year":"2016","journal-title":"Opt. Express"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"8389","DOI":"10.1364\/OE.23.008389","article-title":"Ultrahigh-sensitivity sensors based on thin-film coated long period grating with reduced diameter, in transition mode and near the dispersion turning point","volume":"23","year":"2015","journal-title":"Opt. Express"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1016\/j.bios.2019.03.006","article-title":"Ultrasensitive tantalum oxide nano-coated long-period grating for detection of various biological targets","volume":"133","author":"Dominik","year":"2019","journal-title":"Biosens. Bioelectron."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"11897","DOI":"10.1364\/OE.24.011897","article-title":"Towards refractive index sensitivity of long period gratings at level of tens of \u00b5m per refractive index unit: Fiber cladding etching and nano-coating deposition","volume":"24","author":"Koba","year":"2016","journal-title":"Opt. Express"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"4615","DOI":"10.1109\/JLT.2016.2528411","article-title":"Combined plasma-based fiber etching and diamond-like carbon nanooverlay deposition for enhancing sensitivity of long-period grating","volume":"34","author":"Koba","year":"2016","journal-title":"J. Lightwave Technol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2434","DOI":"10.1109\/JLT.2020.2964769","article-title":"Vertical-fluid-array-induced optical microfiber long-period grating (VIOLIN) refractometer","volume":"38","author":"Ran","year":"2020","journal-title":"J. Lightwave Technol."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Hu, D., Xu, Z., Long, J., Xiao, P., Liang, L., Sun, L., Liang, H., Ran, Y., and Guan, B.O. (2020). Label-free and reproducible chemical sensor using the vertical-fluid-array induced optical fiber long period grating (VIOLIN). Sensors, 20.","DOI":"10.3390\/s20123415"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"686","DOI":"10.1364\/OL.28.000686","article-title":"Theory and practice of long-period gratings: When a loss becomes a gain","volume":"28","author":"Daxhelet","year":"2003","journal-title":"Opt. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2221","DOI":"10.1364\/OE.16.002221","article-title":"Apodisation of photo-induced waveguide gratings using double-exposure with complementary duty cycles","volume":"16","author":"Shu","year":"2008","journal-title":"Opt. Express"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1016\/j.optcom.2004.09.078","article-title":"Analysis of apodized phase-shifted long-period fiber gratings","volume":"244","author":"Chan","year":"2005","journal-title":"Opt. Commun."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/8\/2965\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T22:52:50Z","timestamp":1760136770000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/8\/2965"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,4,12]]},"references-count":24,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2022,4]]}},"alternative-id":["s22082965"],"URL":"https:\/\/doi.org\/10.3390\/s22082965","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2022,4,12]]}}}