{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,18]],"date-time":"2026-01-18T08:45:02Z","timestamp":1768725902386,"version":"3.49.0"},"reference-count":54,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2018,6,7]],"date-time":"2018-06-07T00:00:00Z","timestamp":1528329600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the Spanish Agencia Estatal de Investigaci\u00f3n (AEI) and Fondo Europeo de Desarrollo Regional (FEDER)","award":["TEC2016-78047-R & TEC2016-79367-C2-2-R"],"award-info":[{"award-number":["TEC2016-78047-R & TEC2016-79367-C2-2-R"]}]},{"name":"Government of Navarre","award":["2017\/PI044"],"award-info":[{"award-number":["2017\/PI044"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Here, we present a novel method to fabricate long period gratings using standard single mode optical fibers (SMF). These optical devices were fabricated in a three-step process, which consisted of etching the SMF, then coating it with a thin-film and, the final step, which involved removing sections of the coating periodically by laser ablation. Tin dioxide was chosen as the material for this study and it was sputtered using a pulsed DC sputtering system. Theoretical simulations were performed in order to select the appropriate parameters for the experiments. The responses of two different devices to different external refractive indices was studied, and the maximum sensitivity obtained was 6430 nm\/RIU for external refractive indices ranging from 1.37 to 1.39.<\/jats:p>","DOI":"10.3390\/s18061866","type":"journal-article","created":{"date-parts":[[2018,6,8]],"date-time":"2018-06-08T03:13:18Z","timestamp":1528427598000},"page":"1866","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Fabrication of Long Period Gratings by Periodically Removing the Coating of Cladding-Etched Single Mode Optical Fiber Towards Optical Fiber Sensor Development"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0304-3394","authenticated-orcid":false,"given":"Joaquin","family":"Ascorbe","sequence":"first","affiliation":[{"name":"Department of Electrical, Electronic and Communication Engineering, Public University of Navarra, 31006 Pamplona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1298-5700","authenticated-orcid":false,"given":"Jesus M.","family":"Corres","sequence":"additional","affiliation":[{"name":"Department of Electrical, Electronic and Communication Engineering, Public University of Navarra, 31006 Pamplona, Spain"},{"name":"Institute of Smart Cities, Public University of Navarra, 31006 Pamplona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ignacio","family":"Del Villar","sequence":"additional","affiliation":[{"name":"Department of Electrical, Electronic and Communication Engineering, Public University of Navarra, 31006 Pamplona, Spain"},{"name":"Institute of Smart Cities, Public University of Navarra, 31006 Pamplona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2229-6178","authenticated-orcid":false,"given":"Ignacio R.","family":"Matias","sequence":"additional","affiliation":[{"name":"Department of Electrical, Electronic and Communication Engineering, Public University of Navarra, 31006 Pamplona, Spain"},{"name":"Institute of Smart Cities, Public University of Navarra, 31006 Pamplona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2018,6,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1109\/50.476137","article-title":"Long-period fiber gratings as band-rejection filters","volume":"14","author":"Vengsarkar","year":"1996","journal-title":"J. Light. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1080\/01468030590922975","article-title":"Arc-induced long-period gratings","volume":"24","author":"Rego","year":"2005","journal-title":"Fiber Integr. Opt."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"16372","DOI":"10.3390\/s131216372","article-title":"Capability for fine tuning of the refractive index sensing properties of long-period gratings by atomic layer deposited Al2O3 overlays","volume":"13","author":"Mikulic","year":"2013","journal-title":"Sensors"},{"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 Gratings to External Index of Refraction","volume":"16","author":"Kersey","year":"1998","journal-title":"J. Light. Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1109\/50.983240","article-title":"Sensitivity characteristics of long-period fiber gratings","volume":"20","author":"Shu","year":"2002","journal-title":"J. Light. Technol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"929","DOI":"10.1016\/j.snb.2014.06.035","article-title":"De Enhanced refractive index sensing characteristics of optical fibre long period grating coated with titanium oxide thin films","volume":"202","author":"Coelho","year":"2014","journal-title":"Sens. Actuators B Chem."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"457","DOI":"10.1016\/j.ijleo.2013.06.037","article-title":"Optik Temperature sensitivity of long period fiber grating in SMF-28 fiber","volume":"125","author":"Singh","year":"2014","journal-title":"Opt. Int. J. Light Electron Opt."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1409","DOI":"10.1088\/0957-0233\/14\/8\/329","article-title":"Cryogenic temperature response of fibre optic long period gratings","volume":"14","author":"James","year":"2003","journal-title":"Meas. Sci. Technol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"3414","DOI":"10.1364\/OL.31.003414","article-title":"Highly sensitive long-period fiber-grating strain sensor with low temperature sensitivity","volume":"31","author":"Wang","year":"2006","journal-title":"Opt. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"692","DOI":"10.1364\/OL.21.000692","article-title":"Optical fiber long-period grating sensors","volume":"21","author":"Bhatia","year":"1996","journal-title":"Opt. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"531","DOI":"10.1109\/68.841276","article-title":"Optical bend sensor based on measurement of resonance mode splitting of long-period fiber grating","volume":"12","author":"Liu","year":"2000","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"686","DOI":"10.1364\/OL.27.000686","article-title":"Optical fiber long-period gratings with Langmuir\u2013Blodgett thin-film overlays","volume":"27","author":"Rees","year":"2002","journal-title":"Opt. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2895","DOI":"10.1021\/ac9912395","article-title":"Evanescent Wave Long-Period Fiber Bragg Grating as an Immobilized Antibody Biosensor","volume":"72","author":"DeLisa","year":"2000","journal-title":"Anal. Chem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1458","DOI":"10.1109\/68.803078","article-title":"Tunable loss filter based on metal-coated long-period fiber grating","volume":"11","author":"Costantini","year":"1999","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"34002","DOI":"10.1088\/0957-0233\/20\/3\/034002","article-title":"A fibre optic humidity sensor based on a long-period fibre grating coated with a thin film of SiO2 nanospheres","volume":"20","author":"Viegas","year":"2009","journal-title":"Meas. Sci. Technol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1016\/j.sna.2008.07.015","article-title":"Long period grating-based humidity sensor for potential structural health monitoring","volume":"148","author":"Venugopalan","year":"2008","journal-title":"Sens. Actuators A Phys."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"4567","DOI":"10.1364\/AO.45.004567","article-title":"Optical fiber long-period grating humidity sensor with poly(ethylene oxide)\/cobalt chloride coating","volume":"45","author":"Konstantaki","year":"2006","journal-title":"Appl. Opt."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"455","DOI":"10.1109\/JSEN.2007.891933","article-title":"Design of pH Sensors in Long-Period Fiber Gratings Using Polymeric Nanocoatings","volume":"7","author":"Corres","year":"2007","journal-title":"IEEE Sens. J."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1364\/OL.32.000029","article-title":"Fiber-optic pH-sensors in long-period fiber gratings using electrostatic self-assembly","volume":"32","author":"Corres","year":"2007","journal-title":"Opt. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"629","DOI":"10.1016\/j.snb.2009.10.008","article-title":"Optical fibre long period grating based selective vapour sensing of volatile organic compounds","volume":"143","author":"Topliss","year":"2010","journal-title":"Sens. Actuators B Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1016\/S0030-4018(01)01131-2","article-title":"Detection of organic aromatic compounds in paraffin by a long-period fiber grating optical sensor with optimized sensitivity","volume":"191","author":"Allsop","year":"2001","journal-title":"Opt. Commun."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2405","DOI":"10.1364\/OL.31.002405","article-title":"Optical fiber long-period grating with solgel coating for gas sensor","volume":"31","author":"Gu","year":"2006","journal-title":"Opt. Lett."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2541","DOI":"10.1364\/OL.32.002541","article-title":"Real-time detection of DNA interactions with long-period fiber-grating-based biosensor","volume":"32","author":"Chen","year":"2007","journal-title":"Opt. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Coelho, J.M.P., Silva, C., Nespereira, M., Abreu, M., and Rebord\u00e3o, J. (2015). Writing of Long Period Fiber Gratings Using CO2 Laser Radiation. Advances in Optical Fiber Technology: Fundamental Optical Phenomena and Applications, InTech.","DOI":"10.5772\/59153"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1420","DOI":"10.1016\/j.optlastec.2011.04.011","article-title":"Optics & Laser Technology Femtosecond laser fabrication of long period fiber gratings and applications in refractive index sensing","volume":"43","author":"Li","year":"2011","journal-title":"Opt. Laser Technol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"765","DOI":"10.1364\/OL.26.000765","article-title":"Fabrication of long-period fiber gratings by use of focused ion-beam irradiation","volume":"26","author":"Roberts","year":"2001","journal-title":"Opt. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Park, S., Kwon, O.J., and Han, Y.G. (2010, January 8\u201312). A novel fabrication technique of corrugated long-period fiber gratings for mass production and its transmission characteristic as applied mechnical force. Proceedings of the Communications and Photonics Conference and Exhibition (ACP), 2010 Asia, Shanghai, China.","DOI":"10.1109\/ACP.2010.5682819"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"120211","DOI":"10.1143\/JJAP.48.120211","article-title":"Optical Fiber Sensor Based on Air-Gap Long-Period Fiber Gratings","volume":"48","author":"Fu","year":"2009","journal-title":"Jpn. J. Appl. Phys."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2823","DOI":"10.1016\/j.optcom.2009.03.064","article-title":"Mechanically induced long-period fiber gratings on tapered fibers","volume":"282","year":"2009","journal-title":"Opt. Commun."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"4584","DOI":"10.1109\/JLT.2016.2540678","article-title":"Arc-Induced Long-Period Fiber Gratings in the Dispersion Turning Points","volume":"34","author":"Rego","year":"2016","journal-title":"J. Light. Technol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2000","DOI":"10.1049\/el:20001418","article-title":"Rapid long-period grating formation in hydrogen-loaded fibre with 157 nm F2-laser radiation","volume":"36","author":"Chen","year":"2000","journal-title":"Electron. Lett."},{"key":"ref_32","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 the dispersion turning point","volume":"24","author":"Cruz","year":"2016","journal-title":"Opt. Express"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1191","DOI":"10.1049\/el:19930796","article-title":"High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres","volume":"29","author":"Lemaire","year":"1993","journal-title":"Electron. Lett."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1961","DOI":"10.1109\/LPT.2013.2275007","article-title":"Asymmetrically corrugated long-period gratings by burning fiber coating and etching cladding","volume":"25","author":"Cui","year":"2013","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"33007","DOI":"10.1117\/1.3478238","article-title":"Novel fabrication method of corrugated long-period fiber gratings by thick SU-8 photoresist and wet-etching technique","volume":"9","author":"Chiang","year":"2010","journal-title":"J. Micro\/Nanolithogr. MEMS MOEMS"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"3399","DOI":"10.1109\/JLT.2003.821749","article-title":"Analysis of corrugated long-period gratings in slab waveguides and their polarization dependence","volume":"21","author":"Liu","year":"2003","journal-title":"J. Light. Technol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"2264","DOI":"10.1364\/AO.42.002264","article-title":"Wavelength shifts of cladding-mode resonance in corrugated long-period fiber gratings under torsion","volume":"42","author":"Ivanov","year":"2003","journal-title":"Appl. Opt."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1159","DOI":"10.1109\/50.939797","article-title":"Corrugated long-period fiber gratings as strain, torsion, and bending sensors","volume":"19","author":"Lin","year":"2001","journal-title":"J. Light. Technol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"4172","DOI":"10.1364\/OL.35.004172","article-title":"Leakage coupling of ultrasensitive periodical silica thin-film long-period grating coated on tapered fiber","volume":"35","author":"Lee","year":"2010","journal-title":"Opt. Lett."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1016\/j.snb.2015.09.061","article-title":"Characterization of zinc oxide coated optical fiber long period gratings with improved refractive index sensing properties","volume":"223","author":"Coelho","year":"2016","journal-title":"Sens. Actuators B Chem."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1364\/OPEX.13.000056","article-title":"Optimization of sensitivity in Long Period Fiber Gratings with overlay deposition","volume":"13","author":"Arregui","year":"2005","journal-title":"Opt. Express"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"999","DOI":"10.1016\/j.proeng.2016.11.325","article-title":"Influence of Period on Surrounding Refractive Index Sensitivity of Arc-induced Long Period Gratings","volume":"168","author":"Esposito","year":"2016","journal-title":"Procedia Eng."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Hromadka, J., Korposh, S., Partridge, M., James, S.W., Davis, F., Crump, D., and Tatam, R.P. (2017). Volatile organic compounds sensing using optical fibre long period grating with mesoporous nano-scale coating. Sensors, 17.","DOI":"10.3390\/s17020205"},{"key":"ref_44","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_45","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_46","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 gratings with reduced diameter, in transition mode and near the dispersion turning point","volume":"23","year":"2015","journal-title":"Opt. Express"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"R49","DOI":"10.1088\/0957-0233\/14\/5\/201","article-title":"Optical fibre long-period grating sensors: Characteristics and application","volume":"14","author":"James","year":"2003","journal-title":"Meas. Sci. Technol."},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Del Villar, I., Partridge, M., Rodriguez, W.E., Fuentes, O., Socorro, A.B., Diaz, S., Corres, J.M., James, S.W., and Tatam, R.P. (2017). Sensitivity Enhancement in Low Cutoff Wavelength Long-Period Fiber Gratings by Cladding Diameter Reduction. Sensors, 17.","DOI":"10.3390\/s17092094"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"471","DOI":"10.1049\/el:20058352","article-title":"Refractive index sensing with long-period grating fabricated in biconical tapered fibre","volume":"41","author":"Allsop","year":"2005","journal-title":"Electron. Lett."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"555","DOI":"10.1364\/AO.12.000555","article-title":"Optical Constants of Water in the 200-nm to 200-microm Wavelength Region","volume":"12","author":"Hale","year":"1973","journal-title":"Appl. Opt."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1016\/S0030-4018(02)01185-9","article-title":"Fabrication and characterisation of ultra-long-period fibre gratings","volume":"203","author":"Shu","year":"2002","journal-title":"Opt. Commun."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"305","DOI":"10.1016\/j.bios.2014.04.042","article-title":"Biosensors and Bioelectronics Towards sensitive label-free immunosensing by means of turn-around point long period fi ber gratings","volume":"60","author":"Chiavaioli","year":"2014","journal-title":"Biosens. Bioelectron."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"1240","DOI":"10.1109\/JSEN.2014.2361166","article-title":"Sensitivity Enhancement of Turn-Around-Point Long Period Gratings by Tuning Initial Coupling Condition","volume":"15","author":"Biswas","year":"2015","journal-title":"IEEE Sens. J."},{"key":"ref_54","doi-asserted-by":"crossref","unstructured":"Li, Q.S., Zhang, X.L., Shi, J.G., Xiang, D., Zheng, L., Yang, Y., Yang, J.H., Feng, D., and Dong, W.F. (2016). An ultrasensitive Long-Period fiber grating-based refractive index sensor with long wavelengths. Sensors, 16.","DOI":"10.3390\/s16122205"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/6\/1866\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:07:41Z","timestamp":1760195261000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/6\/1866"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,6,7]]},"references-count":54,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2018,6]]}},"alternative-id":["s18061866"],"URL":"https:\/\/doi.org\/10.3390\/s18061866","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,6,7]]}}}