{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,26]],"date-time":"2026-02-26T04:52:24Z","timestamp":1772081544816,"version":"3.50.1"},"reference-count":41,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2017,6,16]],"date-time":"2017-06-16T00:00:00Z","timestamp":1497571200000},"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 high sensitivity refractive index sensor based on a single mode-small diameter no core fiber structure is proposed. In this structure, a small diameter no core fiber (SDNCF) used as a sensor probe, was fusion spliced to the end face of a traditional single mode fiber (SMF) and the end face of the SDNCF was coated with a thin film of gold to provide reflective light. The influence of SDNCF diameter and length on the refractive index sensitivity of the sensor has been investigated by both simulations and experiments, where results show that the diameter of SDNCF has significant influence. However, SDNCF length has limited influence on the sensitivity. Experimental results show that a sensitivity of 327 nm\/RIU (refractive index unit) has been achieved for refractive indices ranging from 1.33 to 1.38, which agrees well with the simulated results with a sensitivity of 349.5 nm\/RIU at refractive indices ranging from 1.33 to 1.38.<\/jats:p>","DOI":"10.3390\/s17061415","type":"journal-article","created":{"date-parts":[[2017,6,16]],"date-time":"2017-06-16T10:06:31Z","timestamp":1497607591000},"page":"1415","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["High Sensitivity Refractometer Based on Reflective Smf-Small Diameter No Core Fiber Structure"],"prefix":"10.3390","volume":"17","author":[{"given":"Guorui","family":"Zhou","sequence":"first","affiliation":[{"name":"Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China"},{"name":"Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK"}]},{"given":"Qiang","family":"Wu","sequence":"additional","affiliation":[{"name":"Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK"}]},{"given":"Rahul","family":"Kumar","sequence":"additional","affiliation":[{"name":"Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK"}]},{"given":"Wai Pang","family":"Ng","sequence":"additional","affiliation":[{"name":"Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK"}]},{"given":"Hao","family":"Liu","sequence":"additional","affiliation":[{"name":"Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China"}]},{"given":"Longfei","family":"Niu","sequence":"additional","affiliation":[{"name":"Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5002-0849","authenticated-orcid":false,"given":"Nageswara","family":"Lalam","sequence":"additional","affiliation":[{"name":"Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5652-0449","authenticated-orcid":false,"given":"Xiaodong","family":"Yuan","sequence":"additional","affiliation":[{"name":"Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, China"}]},{"given":"Yuliya","family":"Semenova","sequence":"additional","affiliation":[{"name":"Photonics Research Centre, Dublin Institute of Technology, Dublin 8, Ireland"}]},{"given":"Gerald","family":"Farrell","sequence":"additional","affiliation":[{"name":"Photonics Research Centre, Dublin Institute of Technology, Dublin 8, Ireland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7187-2127","authenticated-orcid":false,"given":"Jinhui","family":"Yuan","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"given":"Chongxiu","family":"Yu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"given":"Jie","family":"Zeng","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China"}]},{"given":"Gui Yun","family":"Tian","sequence":"additional","affiliation":[{"name":"School of Electrical, Electronic and Computer Engineering, Newcastle University, Newcastle Upon Tyne NE1 7RU, UK"}]},{"given":"Yong Qing","family":"Fu","sequence":"additional","affiliation":[{"name":"Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle Upon Tyne NE1 8ST, UK"}]}],"member":"1968","published-online":{"date-parts":[[2017,6,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"7937","DOI":"10.1364\/OE.19.007937","article-title":"High sensitivity SMS fiber structure based refractometer-analysis and experiment","volume":"19","author":"Wu","year":"2011","journal-title":"Opt. Express"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4166","DOI":"10.1364\/OL.40.004166","article-title":"High sensitivity refractive index sensor based on a tapered small core single-mode fiber structure","volume":"40","author":"Liu","year":"2015","journal-title":"Opt. Lett."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"151122","DOI":"10.1063\/1.1904716","article-title":"Highly sensitive fiber Bragg grating refractive index sensors","volume":"86","author":"Liang","year":"2005","journal-title":"Appl. Phys. Lett."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Barrias, A., Casas, J.R., and Villalba, S. (2016). A review of distributed optical fiber sensors for civil engineering applications. Sensors, 16.","DOI":"10.3390\/s16050748"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Ramakrishnan, M., Rajan, G., Semenova, Y., and Farrell, G. (2016). Overview of fiber optic sensor technologies for strain\/temperature sensing applications in composite materials. Sensors, 16.","DOI":"10.3390\/s16010099"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1016\/j.snb.2016.12.050","article-title":"Multi-parameter measurements using optical fibre long period gratings for indoor air quality monitoring","volume":"244","author":"Hromadka","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_7","unstructured":"Karabacak, D.M., Farnan, M., Ibrahim, S.K., Todd, M., and Singer, J.M. (2016, January 5\u20138). Fiber optic sensors for multiparameter monitoring of large scale assets. Proceedings of the 8th European Workshop on Structural Health Monitoring, Bilbao, Spain."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"11260","DOI":"10.3390\/s130911260","article-title":"A refractive index sensor based on the resonant coupling to cladding modes in a fiber loop","volume":"13","author":"Reyes","year":"2013","journal-title":"Sensors"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"673","DOI":"10.1016\/j.snb.2016.11.112","article-title":"A fiber ring cavity laser sensor for refractive index and temperature measurement with core-offset modal interferometer as tunable filter","volume":"242","author":"Cai","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"178","DOI":"10.1016\/j.bios.2016.08.040","article-title":"A contemporary approach for design and characterization of fiber-optic-cortisol sensor tailoring LMR and ZnO\/PPY molecularly imprinted film","volume":"87","author":"Usha","year":"2017","journal-title":"Biosens. Bioelectron."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"188","DOI":"10.1016\/j.optcom.2012.12.065","article-title":"Core-cladding mode recoupling based fiber optic refractive index sensor","volume":"294","author":"Zhang","year":"2013","journal-title":"Opt. Commun."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1109","DOI":"10.1016\/j.snb.2016.12.012","article-title":"A wide-range temperature immune refractive-index sensor using concatenated long-period-fiber-gratings","volume":"243","author":"Tripathia","year":"2017","journal-title":"Sens. Actuators B Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1016\/j.optcom.2015.11.015","article-title":"Simultaneous measurement of refractive index and temperature based on asymmetric structures modal interference","volume":"364","author":"Wang","year":"2016","journal-title":"Opt. Commun."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"030604","DOI":"10.3788\/COL201210.030604","article-title":"Temperature-calibrated fiber-optic refractometer based on a compact FBG-SMS structure","volume":"10","author":"Rong","year":"2012","journal-title":"Chin. Opt. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"7888","DOI":"10.1364\/OE.15.007888","article-title":"Optical microfiber coil resonator refractometric sensor","volume":"15","author":"Xu","year":"2007","journal-title":"Opt. Express"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"864","DOI":"10.1109\/JLT.2011.2105462","article-title":"Analytical analysis of side-polished plastic optical fiber as curvature and refractive index sensor","volume":"29","author":"Bilro","year":"2011","journal-title":"J. Lightwave Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"5402","DOI":"10.1364\/OE.20.005402","article-title":"A microfiber coupler tip thermometer","volume":"20","author":"Ding","year":"2012","journal-title":"Opt. Express"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"848","DOI":"10.1109\/LPT.2011.2138126","article-title":"Twisted optical microfiber for refractive index sensing","volume":"23","author":"Liao","year":"2011","journal-title":"IEEE Photonics Technol. Lett."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1016\/j.sbsr.2016.11.003","article-title":"A new structure of photonic crystal fiber with high sensitivity, high nonlinearity, high birefringence and low confinement loss for liquid analyte sensing applications","volume":"12","year":"2017","journal-title":"Sens. Bio-Sens. Res."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.proeng.2015.08.1107","article-title":"A novel photonic crystal fiber biosensor using surface plasmon resonance","volume":"140","author":"Rifat","year":"2016","journal-title":"Procedia Eng."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"212","DOI":"10.1016\/j.snb.2010.05.048","article-title":"Surface plasmon resonance instrument as a refractometer for liquids and ultrathin films","volume":"149","author":"Liang","year":"2010","journal-title":"Sens. Actuators B Chem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"536","DOI":"10.1016\/j.snb.2016.02.074","article-title":"Development of LSPR based U-bent plastic optical fiber sensors","volume":"230","author":"Gowri","year":"2016","journal-title":"Sens. Actuators B Chem."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1249","DOI":"10.1016\/j.proeng.2016.11.437","article-title":"Highly sensitive surface plasmon resonance-based optical fiber multi-parameter sensor","volume":"168","year":"2016","journal-title":"Procedia Eng."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"370","DOI":"10.1364\/JOSAB.27.000370","article-title":"Fiber in-line Mach-Zehder interferometer fabricated by femtosecond laser micromachining for refractive index measurement with high sensitivity","volume":"27","author":"Wang","year":"2010","journal-title":"J. Opt. Soc. Am. B"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"131110","DOI":"10.1063\/1.3115029","article-title":"Tapered fiber Mach-Zehnder interferometer for simultaneous measurement of refractive index and temperature","volume":"94","author":"Lu","year":"2009","journal-title":"Appl. Phys. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"213114","DOI":"10.1063\/1.4808088","article-title":"Nanowire-based refractive index sensor on the tip of an optical fiber","volume":"102","author":"Pevec","year":"2013","journal-title":"Appl. Phys. Lett."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Zhu, S., Pang, F., Huang, S., Zou, F., Guo, Q., Wen, J., and Wang, T. (2016). High sensitivity refractometer based on TiO2-Coated adiabatic tapered optical fiber via ALD technology. Sensors, 16.","DOI":"10.3390\/s16081295"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1016\/j.snb.2016.04.020","article-title":"Chitosan\/PAA based fiber-optic interferometric sensor for heavy metal ions detection","volume":"233","author":"Raghunandhana","year":"2016","journal-title":"Sens. Actuators B Chem."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"185","DOI":"10.1016\/j.snb.2013.06.093","article-title":"Fabry-Perot fiber-optic immunosensor based on suspended layer-by-layer (chitosan\/polystyrene sulfonate) membrane","volume":"188","author":"Chen","year":"2013","journal-title":"Sens. Actuators B Chem."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"125401","DOI":"10.1088\/2040-8978\/13\/12\/125401","article-title":"A comprehensive analysis verified by experiment of a refractometer based on an SMF28-Small-Core Singlemode fiber (SCSMF)-SMF28 fiber structure","volume":"13","author":"Wu","year":"2011","journal-title":"J. Opt."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1016\/j.sna.2013.10.023","article-title":"Investigation of the high sensitivity RI sensor based on SMS fiber structure","volume":"205","author":"Zhao","year":"2014","journal-title":"Sens. Actuators A Phys."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"3149","DOI":"10.1016\/j.optcom.2010.04.027","article-title":"Optimal design and fabrication of SMS fiber temperature sensor for liquid","volume":"283","author":"Gao","year":"2010","journal-title":"Opt. Commun."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"2136","DOI":"10.1016\/j.optcom.2010.01.031","article-title":"Fiber-optic refractive-index sensors based on transmissive and reflective thin-core fier modal interferometers","volume":"283","author":"Xia","year":"2010","journal-title":"Opt. Commun."},{"key":"ref_34","unstructured":"Huang, L.S., Lin, G.R., Fu, M.Y., Sheng, H.J., Sun, H.T., and Liu, W.F. (2013, January 25\u201326). A refractive-index fiber sensor by using no-core fibers. Proceedings of the 2013 IEEE International Symposium on Next-generation Electronics, Kaohsiung, Taiwan."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"6805008","DOI":"10.1109\/JPHOT.2016.2609598","article-title":"Refractive index fiber laser sensor by using tunable filter based on no-core fiber","volume":"8","author":"Zhao","year":"2016","journal-title":"IEEE Photonics J."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1007\/s13320-013-0137-0","article-title":"Multimode interference refractive index sensor based on coreless fiber","volume":"4","author":"Li","year":"2014","journal-title":"Photonic Sens."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Bueno, A., Caucheteur, C., Kinet, D., and M\u00e9gret, P. (2013). Refractive index sensors based on optical fiber hetero-core structure and Fabry-P\u00e9rot interferometers. Proc. SPIE, 8794.","DOI":"10.1117\/12.2026760"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"615","DOI":"10.1109\/50.372474","article-title":"Optical multi-mode interference devices based on self-imaging principles and applications","volume":"13","author":"Soldano","year":"1995","journal-title":"J. Lightwave Technol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"512","DOI":"10.1109\/JLT.2007.915205","article-title":"Investigation on single-mode-multimode-single-mode fiber structure","volume":"26","author":"Wang","year":"2008","journal-title":"J. Lightwave Technol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"469","DOI":"10.1109\/JLT.2004.824379","article-title":"Wavelength tunable fiber lens based on multimode interference","volume":"22","author":"Mohammed","year":"2004","journal-title":"J. Lightwave Technol."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1016\/j.snb.2016.12.126","article-title":"Miniature fiber-optic NH3 gas sensor based on Pt nanoparticle-incorporated graphene oxide","volume":"244","author":"Yu","year":"2017","journal-title":"Sens. Actuators B Chem."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/6\/1415\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T18:39:22Z","timestamp":1760207962000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/17\/6\/1415"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2017,6,16]]},"references-count":41,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2017,6]]}},"alternative-id":["s17061415"],"URL":"https:\/\/doi.org\/10.3390\/s17061415","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2017,6,16]]}}}