{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,21]],"date-time":"2025-10-21T15:35:05Z","timestamp":1761060905658,"version":"build-2065373602"},"reference-count":109,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2019,10,15]],"date-time":"2019-10-15T00:00:00Z","timestamp":1571097600000},"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":["61425007,61635007"],"award-info":[{"award-number":["61425007,61635007"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100010843","name":"Guangzhou Science, Technology and Innovation Commission","doi-asserted-by":"publisher","award":["JCYJ20170412105604705"],"award-info":[{"award-number":["JCYJ20170412105604705"]}],"id":[{"id":"10.13039\/501100010843","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012228","name":"Development and Reform Commission of Shenzhen Municipality","doi-asserted-by":"publisher","award":["none"],"award-info":[{"award-number":["none"]}],"id":[{"id":"10.13039\/501100012228","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper presents a review of our work concerning the recent progress in fabrications and applications of heating-induced long period fiber gratings (LPFGs). Firstly, three kinds of heating fabrication techniques based on CO2 laser, hydrogen\u2013oxygen flame and arc discharge are demonstrated to fabricate LPFGs, i.e., standard LPFGs (SLPFGs) and helical LPFGs (HLPFGs), in different types of optical fibers such as conventional fibers, photonic crystal fibers, and photonic bandgap fibers. Secondly, the all-fiber orbital angular momentum (OAM) mode converters based on heating-induced SLPFGs and HLPFGs in different types of fibers are studied to increase the transmission capacity. Finally, the heating-induced SLPFGs and HLPFGs are investigated to develop various LPFG-based strain, pressure, torsion and biochemical sensors.<\/jats:p>","DOI":"10.3390\/s19204473","type":"journal-article","created":{"date-parts":[[2019,10,16]],"date-time":"2019-10-16T03:32:54Z","timestamp":1571196774000},"page":"4473","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":22,"title":["Recent Progress in Fabrications and Applications of Heating-Induced Long Period Fiber Gratings"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6886-3270","authenticated-orcid":false,"given":"Cailing","family":"Fu","sequence":"first","affiliation":[{"name":"Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China"},{"name":"Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China"}]},{"given":"Yiping","family":"Wang","sequence":"additional","affiliation":[{"name":"Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China"},{"name":"Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China"}]},{"given":"Shen","family":"Liu","sequence":"additional","affiliation":[{"name":"Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China"},{"name":"Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0915-751X","authenticated-orcid":false,"given":"Zhiyong","family":"Bai","sequence":"additional","affiliation":[{"name":"Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China"},{"name":"Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China"}]},{"given":"Changrui","family":"Liao","sequence":"additional","affiliation":[{"name":"Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China"},{"name":"Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9417-2019","authenticated-orcid":false,"given":"Jun","family":"He","sequence":"additional","affiliation":[{"name":"Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China"},{"name":"Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China"}]},{"given":"Ying","family":"Wang","sequence":"additional","affiliation":[{"name":"Guangdong and Hong Kong Joint Research Centre for Optical Fibre Sensors, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China"},{"name":"Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, China"}]}],"member":"1968","published-online":{"date-parts":[[2019,10,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"647","DOI":"10.1063\/1.89881","article-title":"Photosensitivity in optical fiber waveguides-application to reflection filter fabrication","volume":"32","author":"Hill","year":"1978","journal-title":"Appl. Phys. Lett."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1088\/0957-0233\/8\/4\/002","article-title":"In-fibre Bragg grating sensors","volume":"8","author":"Rao","year":"1997","journal-title":"Meas. Sci. Technol."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1016\/S0143-8166(99)00025-1","article-title":"Recent progress in applications of in-fibre Bragg grating sensors","volume":"31","author":"Rao","year":"1999","journal-title":"Opt. Lasers Eng."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"387","DOI":"10.1364\/OE.22.000387","article-title":"Fabrication of high quality, ultra-long fiber Bragg gratings: Up to 2 million periods in phase","volume":"22","author":"Gagne","year":"2014","journal-title":"Opt. Express"},{"key":"ref_5","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_6","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1049\/el:19980239","article-title":"Long-period fibre grating fabrication with focused CO2 laser pulses","volume":"34","author":"Davis","year":"1998","journal-title":"Electron. Lett."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1416","DOI":"10.1049\/el:19980978","article-title":"CO2 laser-induced long-period fibre gratings: Spectral characteristics, cladding modes and polarisation independence","volume":"34","author":"Davis","year":"1998","journal-title":"Electron. Lett."},{"key":"ref_8","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. Lightware Technol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1126\/science.1097631","article-title":"Chiral fiber gratings","volume":"305","author":"Kopp","year":"2004","journal-title":"Science"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1464","DOI":"10.1364\/OL.29.001464","article-title":"Fabrication of helical long-period fiber gratings by use of a CO2 laser","volume":"29","author":"Oh","year":"2004","journal-title":"Opt. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1430","DOI":"10.1364\/AO.55.001430","article-title":"Helical long-period grating formed in a thinned fiber and its application to a refractometric sensor","volume":"55","author":"Wang","year":"2016","journal-title":"Appl. Opt."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"4702","DOI":"10.1364\/AO.56.004702","article-title":"Chiral long-period gratings: Fabrication, highly sensitive torsion sensing, and tunable single-band filtering","volume":"56","author":"Kong","year":"2017","journal-title":"Appl. Opt."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1683","DOI":"10.1109\/JLT.2017.2787120","article-title":"Orbital angular momentum mode converter based on helical long period fiber Grating Inscribed by Hydrogen-Oxygen Flame","volume":"36","author":"Fu","year":"2018","journal-title":"J. Lightware Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1786","DOI":"10.1364\/OL.43.001786","article-title":"High-order orbital angular momentum mode generator based on twisted photonic crystal fiber","volume":"43","author":"Fu","year":"2018","journal-title":"Opt. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1364\/OL.44.000459","article-title":"Twist-direction-dependent orbital angular momentum generator based on inflation-assisted helical photonic crystal fiber","volume":"44","author":"Fu","year":"2019","journal-title":"Opt. Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1984","DOI":"10.1364\/OL.44.001984","article-title":"Transverse-load, strain, temperature, and torsion sensors based on a helical photonic crystal fiber","volume":"44","author":"Fu","year":"2019","journal-title":"Opt. Lett."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1364\/OL.44.000061","article-title":"Polarization-independent orbital angular momentum generator based on a chiral fiber grating","volume":"44","author":"Zhang","year":"2019","journal-title":"Opt. Lett."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"446","DOI":"10.1126\/science.1223824","article-title":"Excitation of orbital angular momentum resonances in helically twisted photonic crystal fiber","volume":"337","author":"Wong","year":"2012","journal-title":"Science"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"5401","DOI":"10.1364\/OL.38.005401","article-title":"Measuring mechanical strain and twist using helical photonic crystal fiber","volume":"38","author":"Xi","year":"2013","journal-title":"Opt. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"165","DOI":"10.1364\/OPTICA.1.000165","article-title":"Orbital-angular-momentum-preserving helical Bloch modes in twisted photonic crystal fiber","volume":"1","author":"Xi","year":"2014","journal-title":"Optica"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"143903","DOI":"10.1103\/PhysRevLett.110.143903","article-title":"Optical activity in twisted solid-core photonic crystal fibers","volume":"110","author":"Xi","year":"2013","journal-title":"Phys. Rev. Lett."},{"key":"ref_22","first-page":"24113","article-title":"Residual-stress-induced helical long period fiber gratings for sensing applications","volume":"26","author":"Li","year":"2018","journal-title":"Opt. Express"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1320","DOI":"10.1109\/JLT.2003.810561","article-title":"Novel fiber-optic sensors based on long-period fiber gratings written by high-frequency CO2 laser pulses","volume":"21","author":"Rao","year":"2003","journal-title":"J. Lightwave Technol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"209","DOI":"10.1016\/j.optcom.2003.10.048","article-title":"Novel long-period fiber gratings written by high-frequency CO2 laser pulses and applications in optical fiber communication","volume":"229","author":"Rao","year":"2004","journal-title":"Opt. Commun."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"151105","DOI":"10.1063\/1.2360253","article-title":"Asymmetric long period fiber gratings fabricated by use of CO2 laser to carve periodic grooves on the optical fiber","volume":"89","author":"Wang","year":"2006","journal-title":"Appl. Phys. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"13208","DOI":"10.1364\/OE.21.013208","article-title":"Long-period gratings inscribed in photonic crystal fiber by symmetric CO2 laser irradiation","volume":"21","author":"Tian","year":"2013","journal-title":"Opt. Express"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2784","DOI":"10.1364\/OE.16.002784","article-title":"Long period gratings in air-core photonic bandgap fibers","volume":"16","author":"Wang","year":"2008","journal-title":"Opt. Express"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/JPHOT.2014.2337875","article-title":"Long period fiber gratings inscribed with an improved two-dimensional scanning technique","volume":"6","author":"Zhong","year":"2014","journal-title":"IEEE Photon. J."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1791","DOI":"10.1364\/OL.40.001791","article-title":"Temperature-insensitivity gas pressure sensor based on inflated long period fiber grating inscribed in photonic crystal fiber","volume":"40","author":"Zhong","year":"2015","journal-title":"Opt. Lett."},{"key":"ref_30","first-page":"1","article-title":"Gas pressure sensor based on CO2-laser-induced long-period fiber grating in air-core photonic bandgap fiber","volume":"7","author":"Tang","year":"2015","journal-title":"IEEE Photon. J."},{"key":"ref_31","first-page":"1","article-title":"Long period fiber grating inscribed in hollow-core photonic bandgap fiber for gas pressure sensing","volume":"9","author":"Tang","year":"2017","journal-title":"IEEE Photon. J."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/JPHOT.2015.2493721","article-title":"Thin-core-fiber-based long-period fiber grating for high-sensitivity refractive index measurement","volume":"7","author":"Fu","year":"2015","journal-title":"IEEE Photon. J."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"349","DOI":"10.1049\/el:20030271","article-title":"Electric arc-induced long-period gratings in Ge-free air-silica microstructure fibres","volume":"39","author":"Humbert","year":"2003","journal-title":"Electron. Lett."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1016\/j.optcom.2005.12.064","article-title":"Polarization dependent loss of arc-induced long-period fibre gratings","volume":"262","author":"Rego","year":"2006","journal-title":"Opt. Commun."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"698","DOI":"10.1109\/LPT.2014.2302901","article-title":"Long period fiber gratings inscribed by periodically tapering a fiber","volume":"26","author":"Yin","year":"2014","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"3873","DOI":"10.1364\/AO.55.003873","article-title":"Automatic arc discharge technology for inscribing long period fiber gratings","volume":"55","author":"Yin","year":"2016","journal-title":"Appl. Opt."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"873","DOI":"10.1109\/LPT.2017.2693361","article-title":"Automatic arc discharge-induced helical long period fiber gratings and its sensing applications","volume":"29","author":"Sun","year":"2017","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"655","DOI":"10.1364\/OL.43.000655","article-title":"Few-period helically twisted all-solid photonic bandgap fibers","volume":"43","author":"Li","year":"2018","journal-title":"Opt. Lett."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"646","DOI":"10.1364\/OL.24.000646","article-title":"Fabrication of long-period fiber gratings by focused irradiation of infrared femtosecond laser pulses","volume":"24","author":"Kondo","year":"1999","journal-title":"Opt. Lett."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Tang, J., Fu, C., Bai, Z., Liao, C., and Wang, Y. (2018). Sensing characteristics of tilted long period fiber gratings inscribed by infrared femtosecond laser. Sensors, 18.","DOI":"10.3390\/s18093003"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"6253","DOI":"10.1364\/OE.19.006253","article-title":"Mechanically-induced pi-shifted long-period fiber gratings","volume":"19","author":"Zhou","year":"2011","journal-title":"Opt. Express"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"2007","DOI":"10.1364\/AO.54.002007","article-title":"Widely tunable LP11 cladding-mode resonance in a twisted mechanically induced long-period fiber grating","volume":"54","author":"Nair","year":"2015","journal-title":"Appl. Opt."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1872","DOI":"10.1049\/el:19991143","article-title":"Loss-tunable long period fibre grating made from etched corrugation structure","volume":"35","author":"Lin","year":"1999","journal-title":"Electron. Lett."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1364\/OL.37.000193","article-title":"Perfectly notched long-period fiber grating filter based on ICP dry etching technique","volume":"37","author":"Chiang","year":"2012","journal-title":"Opt. Lett."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1364\/OL.25.000088","article-title":"Fabrication of long-period optical fiber gratings by use of ion implantation","volume":"25","author":"Fujimaki","year":"2000","journal-title":"Opt. Lett."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"14308","DOI":"10.1364\/OE.25.014308","article-title":"Long period fiber grating based on periodically screw-type distortions for torsion sensing","volume":"25","author":"Deng","year":"2017","journal-title":"Opt. Express"},{"key":"ref_47","first-page":"1","article-title":"Sensing characterization of helical long period fiber grating fabricated by a double-side CO2 Laser in single-mode fiber","volume":"11","author":"Li","year":"2019","journal-title":"IEEE Photon. J."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"5463","DOI":"10.1364\/OL.39.005463","article-title":"High-sensitivity strain sensor based on inflated long period fiber grating","volume":"39","author":"Zhong","year":"2014","journal-title":"Opt. Lett."},{"key":"ref_49","doi-asserted-by":"crossref","unstructured":"Liu, S., Zhang, Y., Fu, C., and Bai, Z. (2018). Temperature insensitivity polarization-controlled orbital angular momentum mode converter based on an LPFG induced in four-mode fiber. Sensors, 18.","DOI":"10.3390\/s18061766"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"072004","DOI":"10.7567\/1882-0786\/ab265f","article-title":"Orbital angular momentum generator based on hollow-core photonic bandgap fiber grating","volume":"12","author":"Bai","year":"2019","journal-title":"Appl. Phys. Express"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"4376","DOI":"10.1364\/OL.40.004376","article-title":"Controllable all-fiber orbital angular momentum mode converter","volume":"40","author":"Li","year":"2015","journal-title":"Opt. Lett."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"6186","DOI":"10.1364\/OE.24.006186","article-title":"Mode converter based on the long-period fiber gratings written in the two-mode fiber","volume":"24","author":"Zhao","year":"2016","journal-title":"Opt. Express"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"4708","DOI":"10.1364\/OL.42.004708","article-title":"All-fiber mode converter based on long-period fiber gratings written in few-mode fiber","volume":"42","author":"Zhao","year":"2017","journal-title":"Opt. Lett."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"5210","DOI":"10.1364\/OL.42.005210","article-title":"All-fiber second-order optical vortex generation based on strong modulated long-period grating in a four-mode fiber","volume":"42","author":"Wu","year":"2017","journal-title":"Opt. Lett."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"19278","DOI":"10.1364\/OE.24.019278","article-title":"Optical vortex generation with wavelength tunability based on an acoustically-induced fiber grating","volume":"24","author":"Zhang","year":"2016","journal-title":"Opt. Express"},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"5082","DOI":"10.1364\/OL.41.005082","article-title":"High-order optical vortex generation in a few-mode fiber via cascaded acoustically driven vector mode conversion","volume":"41","author":"Zhang","year":"2016","journal-title":"Opt. Lett."},{"key":"ref_57","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_58","doi-asserted-by":"crossref","first-page":"1232","DOI":"10.1109\/LPT.2009.2024646","article-title":"Bending and strain sensitivities in a helicoidal long-period fiber gratings","volume":"21","author":"Jung","year":"2009","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1109\/LPT.2017.2787157","article-title":"Torsion, Strain, and temperature sensor based on helical long-period fiber gratings","volume":"30","author":"Subramanian","year":"2018","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"46633","DOI":"10.1038\/srep46633","article-title":"Highly sensitive strain sensor based on helical structure combined with Mach-Zehnder interferometer in multicore fiber","volume":"7","author":"Zhang","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"543","DOI":"10.1109\/LPT.2009.2014566","article-title":"High-sensitivity temperature-independent strain sensor based on a long-period fiber grating with a CO2-laser engraved rotary structure","volume":"21","author":"Zhu","year":"2009","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1109\/LPT.2014.2385067","article-title":"Fabrication of phase-shifted long-period fiber grating and its application to strain measurement","volume":"27","author":"Wang","year":"2015","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"1085","DOI":"10.1109\/LPT.2017.2702573","article-title":"Highly strain and bending sensitive microtapered long-period fiber gratings","volume":"29","author":"Ren","year":"2017","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/JPHOT.2019.2891245","article-title":"High strain sensitivity temperature sensor based on a secondary modulated tapered long Period Fiber Grating","volume":"11","author":"Jin","year":"2019","journal-title":"IEEE Photon. J."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"1176","DOI":"10.1109\/TIM.2007.899904","article-title":"A novel fiber-optic tapered long-period grating sensor for pressure monitoring","volume":"56","author":"Bock","year":"2007","journal-title":"IEEE Trans. Instrum. Meas."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"3098","DOI":"10.1088\/0957-0233\/18\/10\/S08","article-title":"Pressure sensing using periodically tapered long-period gratings written in photonic crystal fibres","volume":"18","author":"Bock","year":"2007","journal-title":"Meas. Sci. Technol."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"922","DOI":"10.1002\/lpor.201600111","article-title":"Lab on fiber technology for biological sensing applications","volume":"10","author":"Vaiano","year":"2016","journal-title":"Laser Photon. Rev."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"1541","DOI":"10.1039\/b806129g","article-title":"Chemical sensor based on a long-period fibre grating modified by a functionalized polydimethylsiloxane coating","volume":"133","author":"Barnes","year":"2008","journal-title":"Analyst"},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"693","DOI":"10.1016\/j.bios.2015.12.089","article-title":"Long period fiber grating based sensor for the detection of triacylglycerides","volume":"79","author":"Baliyan","year":"2016","journal-title":"Biosens. Bioelectron."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"2483","DOI":"10.1016\/j.snb.2017.09.041","article-title":"Carbon dioxide measurements using long period grating optical fibre sensor coated with metal organic framework HKUST-1","volume":"255","author":"Hromadka","year":"2018","journal-title":"Sens. Actuator B Chem."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"14696","DOI":"10.1364\/OE.19.014696","article-title":"Long-period fiber grating sensor with a styrene-acrylonitrile nano-film incorporating cryptophane A for methane detection","volume":"19","author":"Yang","year":"2011","journal-title":"Opt. Express"},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"178","DOI":"10.1177\/1475921714560070","article-title":"Steel bar corrosion monitoring with long-period fiber grating sensors coated with nano iron\/silica particles and polyurethane","volume":"14","author":"Huang","year":"2015","journal-title":"Struct. Health Monit."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"2306","DOI":"10.1364\/OL.41.002306","article-title":"A Fe-C coated long-period fiber grating sensor for corrosion-induced mass loss measurement","volume":"41","author":"Chen","year":"2016","journal-title":"Opt. Lett."},{"key":"ref_74","first-page":"11","article-title":"Review of long period fiber gratings written by CO2 laser","volume":"108","author":"Wang","year":"2010","journal-title":"J. Appl. Phys."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"5442","DOI":"10.1364\/OE.24.005442","article-title":"Flat-top band-rejection filter based on two successively-cascaded helical fiber gratings","volume":"24","author":"Inoue","year":"2016","journal-title":"Opt. Express"},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"1629","DOI":"10.1109\/LPT.2016.2555326","article-title":"High sensitivity twist sensor based on helical long-period grating written in two-mode fiber","volume":"28","author":"Zhang","year":"2016","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"10405","DOI":"10.1364\/OE.25.010405","article-title":"Helical long-period grating manufactured with a CO2 laser on multicore fiber","volume":"25","author":"Shen","year":"2017","journal-title":"Opt. Express"},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"889","DOI":"10.1109\/JLT.2018.2883376","article-title":"Helical long-period gratings inscribed in polarization-maintaining fibers by CO2 laser","volume":"37","author":"Jiang","year":"2019","journal-title":"J. Lightwave Technol."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"1214","DOI":"10.1364\/OL.32.001214","article-title":"Bandwidth-tunable band-rejection filter based on helicoidal fiber grating pair of opposite helicities","volume":"32","author":"Shin","year":"2007","journal-title":"Opt. Lett."},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"1084","DOI":"10.1109\/50.857754","article-title":"Cladding-mode-resonances in air-silica microstructure optical fibers","volume":"18","author":"Eggleton","year":"2000","journal-title":"J. Lightwave Technol."},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"2287","DOI":"10.1109\/JLT.2014.2323403","article-title":"Sensing Characteristics of femtosecond laser-induced long period gratings by filling cladding holes in photonic crystal fiber","volume":"32","author":"Luo","year":"2014","journal-title":"J. Lightwave Technol."},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"1013","DOI":"10.1364\/OL.27.001013","article-title":"Structural long-period gratings in photonic crystal fibers","volume":"27","author":"Kakarantzas","year":"2002","journal-title":"Opt. Lett."},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"2467","DOI":"10.1364\/OL.28.002467","article-title":"Deep-notch, ultracompact long-period grating in a large-mode-area photonic crystal fiber","volume":"28","author":"Zhu","year":"2003","journal-title":"Opt. Lett."},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1364\/OL.30.000367","article-title":"Strain-insensitive and high-temperature long-period gratings inscribed in photonic crystal fiber","volume":"30","author":"Zhu","year":"2005","journal-title":"Opt. Lett."},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"132","DOI":"10.1109\/LPT.2007.912531","article-title":"Writing of long-period gratings in conventional and photonic-crystal polarization-maintaining fibers by CO2-laser pulses","volume":"20","author":"Lee","year":"2008","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"3290","DOI":"10.1364\/OL.30.003290","article-title":"Fabrication of long-period fiber gratings by twisting a standard single-mode fiber","volume":"30","author":"Ivanov","year":"2005","journal-title":"Opt. Lett."},{"key":"ref_87","doi-asserted-by":"crossref","first-page":"20150440","DOI":"10.1098\/rsta.2015.0440","article-title":"Helically twisted photonic crystal fibres","volume":"375","author":"Russell","year":"2017","journal-title":"Philos. Trans. R. Soc. A Math. Phys. Eng. Sci."},{"key":"ref_88","doi-asserted-by":"crossref","first-page":"26515","DOI":"10.1364\/OE.19.026515","article-title":"Angular-momentum coupled optical waves in chirally-coupled-core fibers","volume":"19","author":"Ma","year":"2011","journal-title":"Opt. Express"},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"1672","DOI":"10.1364\/OL.41.001672","article-title":"Current sensing using circularly birefringent twisted solid-core photonic crystal fiber","volume":"41","author":"Beravat","year":"2016","journal-title":"Opt. Lett."},{"key":"ref_90","doi-asserted-by":"crossref","first-page":"15361","DOI":"10.1364\/OE.18.015361","article-title":"High order resonances between core mode and cladding supermodes in long period fiber gratings inscribed in photonic bandgap fibers","volume":"18","author":"Tai","year":"2010","journal-title":"Opt. Express"},{"key":"ref_91","doi-asserted-by":"crossref","first-page":"315","DOI":"10.1515\/nanoph-2013-0042","article-title":"Hollow-core photonic bandgap fibers: technology and applications","volume":"2","author":"Poletti","year":"2013","journal-title":"Nanophotonics"},{"key":"ref_92","doi-asserted-by":"crossref","first-page":"1574","DOI":"10.1109\/50.956145","article-title":"High-temperature stability of long-period fiber gratings produced using an electric arc","volume":"19","author":"Rego","year":"2001","journal-title":"J. Lightwave Technol."},{"key":"ref_93","doi-asserted-by":"crossref","first-page":"13936","DOI":"10.1364\/OE.15.013936","article-title":"Origin of coupling to antisymmetric modes in arc-induced long-period fiber gratings","volume":"15","author":"Ivanov","year":"2007","journal-title":"Opt. Express"},{"key":"ref_94","doi-asserted-by":"crossref","unstructured":"Esposito, F., Ranjan, R., Campopiano, S., and Iadicicco, A. (2018). Arc-induced long period gratings from standard to polarization-maintaining and photonic crystal fibers. Sensors, 18.","DOI":"10.3390\/s18030918"},{"key":"ref_95","doi-asserted-by":"crossref","first-page":"1567","DOI":"10.1109\/LPT.2011.2164518","article-title":"Long-Period gratings in hollow core Fibers by pressure-assisted arc discharge technique","volume":"23","author":"Iaducucco","year":"2011","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_96","first-page":"1533","article-title":"Arc-Induced Long Period Gratings in Polarization-Maintaining Panda Fiber","volume":"29","author":"Iaducucco","year":"2017","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_97","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1364\/OPTICA.2.000267","article-title":"Conservation of orbital angular momentum in air-core optical fibers","volume":"2","author":"Gregg","year":"2015","journal-title":"Optica"},{"key":"ref_98","doi-asserted-by":"crossref","first-page":"S17","DOI":"10.1088\/1464-4266\/4\/2\/362","article-title":"Orbital angular momentum exchange in cylindrical-lens mode converters","volume":"4","author":"Padgett","year":"2002","journal-title":"J. Opt. B Quantum Semiclassical Opt."},{"key":"ref_99","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1126\/science.1226528","article-title":"Integrated Compact Optical Vortex Beam Emitters","volume":"338","author":"Cai","year":"2012","journal-title":"Science"},{"key":"ref_100","doi-asserted-by":"crossref","first-page":"932","DOI":"10.1364\/OL.38.000932","article-title":"Metamaterials-based broadband generation of orbital angular momentum carrying vector beams","volume":"38","author":"Zhao","year":"2013","journal-title":"Opt. Lett."},{"key":"ref_101","doi-asserted-by":"crossref","first-page":"793","DOI":"10.1088\/0957-0233\/12\/7\/307","article-title":"A torsion sensor made of a corrugated long period fibre grating","volume":"12","author":"Wang","year":"2001","journal-title":"Meas. Sci. Technol."},{"key":"ref_102","doi-asserted-by":"crossref","first-page":"1539","DOI":"10.1109\/LPT.2010.2068043","article-title":"Temperature-insensitive torsion sensor with enhanced sensitivity by use of a highly birefringent photonic crystal fiber","volume":"22","author":"Kim","year":"2010","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_103","doi-asserted-by":"crossref","first-page":"2715","DOI":"10.1109\/JLT.2011.2163196","article-title":"UV-Inscription, Polarization-dependant loss characteristics and applications of 45\u00b0 tilted fiber gratings","volume":"29","author":"Yan","year":"2011","journal-title":"J. Lightwave Technol."},{"key":"ref_104","doi-asserted-by":"crossref","first-page":"28839","DOI":"10.1364\/OE.20.028839","article-title":"Orthogonal polarization mode coupling for pure twisted polarization maintaining fiber Bragg gratings","volume":"20","author":"Yang","year":"2012","journal-title":"Opt. Express"},{"key":"ref_105","doi-asserted-by":"crossref","first-page":"920","DOI":"10.1109\/LPT.2011.2143400","article-title":"A Temperature-insensitive twist sensor by using low-birefringence photonic-crystal-fiber-based sagnac interferometer","volume":"23","author":"Zu","year":"2011","journal-title":"IEEE Photon. Technol. Lett."},{"key":"ref_106","doi-asserted-by":"crossref","first-page":"2844","DOI":"10.1364\/OE.20.002844","article-title":"Twist sensor based on axial strain insensitive distributed Bragg reflector fiber laser","volume":"20","author":"Wo","year":"2012","journal-title":"Opt. Express"},{"key":"ref_107","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1049\/el:20040117","article-title":"Long period fibre grating torsion sensor measuring twist rate and determining twist direction simultaneously","volume":"40","author":"Wang","year":"2004","journal-title":"Electron. Lett."},{"key":"ref_108","doi-asserted-by":"crossref","first-page":"1167","DOI":"10.1364\/JOSAB.22.001167","article-title":"Torsion characteristics of long-period fiber gratings induced by high-frequency CO2 laser pulses","volume":"22","author":"Wang","year":"2005","journal-title":"J. Opt. Soc. Am. B Opt. Phys."},{"key":"ref_109","doi-asserted-by":"crossref","first-page":"544","DOI":"10.1364\/OE.26.000544","article-title":"Directional torsion and temperature discrimination based on a multicore fiber with a helical structure","volume":"26","author":"Zhang","year":"2018","journal-title":"Opt. Express"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/20\/4473\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T13:26:37Z","timestamp":1760189197000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/20\/4473"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,10,15]]},"references-count":109,"journal-issue":{"issue":"20","published-online":{"date-parts":[[2019,10]]}},"alternative-id":["s19204473"],"URL":"https:\/\/doi.org\/10.3390\/s19204473","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2019,10,15]]}}}