{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T23:27:30Z","timestamp":1767914850239,"version":"3.49.0"},"reference-count":45,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2019,3,8]],"date-time":"2019-03-08T00:00:00Z","timestamp":1552003200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"The National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["61865008"],"award-info":[{"award-number":["61865008"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"The National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["61505074"],"award-info":[{"award-number":["61505074"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"The Undergraduate Innovation Training Program of Gansu Province","award":["DC2018002"],"award-info":[{"award-number":["DC2018002"]}]},{"name":"The Undergraduate Innovation Training Program of Lanzhou University of Technology","award":["DC2018004"],"award-info":[{"award-number":["DC2018004"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This study proposes a highly sensitive refractive-index (RI) sensor based on a TM0 waveguide mode resonance excited in an asymmetric metal-cladding dielectric waveguide structure, where the analyte serves as the guiding layer. By scanning the wavelength at fixed angles of incidence, the reflection spectra of the sensor were obtained. The results showed that the resonance wavelength redshifted dramatically with increases in the analyte RI, which indicates that this approach can be used to sense both the resonance wavelength and the analyte RI. Based on this approach, we investigated the sensing properties, including the sensitivity and figure of merit, at fixed incident angles of 60\u00b0 and 45\u00b0, at which the sensitivity of the sensor reached 7724.9 nm\/RIU (refractive index units) and 1339 nm\/RIU, respectively. Compared with surface plasmon resonance sensors, which are based on a similar structure, the proposed sensor can accept a more flexible range of incident angles and a wider sensing range of analyte RI. This approach thus has tremendous potential for use in numerous sensing domains, such as biochemical and medical analyses.<\/jats:p>","DOI":"10.3390\/s19051187","type":"journal-article","created":{"date-parts":[[2019,3,8]],"date-time":"2019-03-08T04:58:35Z","timestamp":1552021115000},"page":"1187","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":49,"title":["Theoretical Investigation of a Highly Sensitive Refractive-Index Sensor Based on TM0 Waveguide Mode Resonance Excited in an Asymmetric Metal-Cladding Dielectric Waveguide Structure"],"prefix":"10.3390","volume":"19","author":[{"given":"Xiangxian","family":"Wang","sequence":"first","affiliation":[{"name":"School of Science, Lanzhou University of Technology, Lanzhou 730050, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiaoxiong","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Science, Lanzhou University of Technology, Lanzhou 730050, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiankai","family":"Zhu","sequence":"additional","affiliation":[{"name":"School of Science, Lanzhou University of Technology, Lanzhou 730050, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhiyuan","family":"Pang","sequence":"additional","affiliation":[{"name":"School of Science, Lanzhou University of Technology, Lanzhou 730050, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7418-578X","authenticated-orcid":false,"given":"Hua","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Science, Lanzhou University of Technology, Lanzhou 730050, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yunping","family":"Qi","sequence":"additional","affiliation":[{"name":"College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,3,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"706","DOI":"10.1364\/OME.9.000706","article-title":"Tunable absorption enhancement in periodic elliptical hollow graphene arrays","volume":"9","author":"Cen","year":"2019","journal-title":"Opt. Mater. Express"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"045807","DOI":"10.1088\/2053-1591\/aafc3e","article-title":"Plasmonic absorption enhancement in grapheme circular and elliptical disk arrays","volume":"6","author":"Lin","year":"2019","journal-title":"Mater. Res. Express"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1529","DOI":"10.1109\/LPT.2016.2556220","article-title":"Optical Magnetic Field Enhancement via Coupling Magnetic Plasmons to Optical Cavity Modes","volume":"28","author":"Chen","year":"2016","journal-title":"IEEE Photonic Technol. Lett."},{"key":"ref_4","first-page":"4800107","article-title":"Surface-plasmon-polaritons-assisted enhanced magnetic response at optical frequencies in metamaterials","volume":"8","author":"Chen","year":"2016","journal-title":"IEEE Photonics J."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1612","DOI":"10.1002\/adfm.201202148","article-title":"A Review of Surface Plasmon Resonance-Enhanced Photocatalysis","volume":"23","author":"Hou","year":"2013","journal-title":"Adv. Funct. Mater."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"180","DOI":"10.1016\/j.materresbull.2018.07.018","article-title":"Synthesis and theoretical study of large-sized Bi4Ti3O12 square nanosheets with high photocatalytic activity","volume":"107","author":"Zhao","year":"2018","journal-title":"Mater. Res. Bull."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Di, L.J., Yang, H., Xian, T., and Chen, X.J. (2018). Construction of Z-scheme g-C3N4\/CNT\/Bi2Fe4O9 composites with improved simulated-sunlight photocatalytic activity for the dye degradation. Micromachines, 9.","DOI":"10.3390\/mi9120613"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"286","DOI":"10.1016\/j.materresbull.2018.05.008","article-title":"Enhanced photocatalytic activity of surface disorder-engineered CaTiO3","volume":"105","author":"Yan","year":"2018","journal-title":"Mater. Res. Bull."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"608","DOI":"10.1186\/s11671-017-2377-1","article-title":"A novel Bi4Ti3O12\/Ag3PO4 heterojunction photocatalyst with enhanced photocatalytic performance","volume":"12","author":"Zheng","year":"2017","journal-title":"Nanoscale Res. Lett."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"257","DOI":"10.1186\/s11671-018-2671-6","article-title":"Facile synthesis and enhanced visible-light photocatalytic activity of novel p-Ag3PO4\/n-BiFeO3 heterojunction composites for dye degradation","volume":"13","author":"Di","year":"2018","journal-title":"Nanoscale Res Lett."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"072112","DOI":"10.1063\/1.4993054","article-title":"The role of terahertz surface plasmons in the scattering pattern of electromagnetic waves in an unstable elliptical plasma antenna","volume":"24","author":"Safaria","year":"2017","journal-title":"Phys. Plasmas"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"115001","DOI":"10.1088\/2058-6272\/aacaef","article-title":"THz plasma wave instability in field effect transistor with electron diffusion current density","volume":"20","author":"Du","year":"2018","journal-title":"Plasma Sci. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"045002","DOI":"10.1088\/2058-6272\/aaf874","article-title":"The instability of terahertz plasma waves in cylindrical FET","volume":"21","author":"Li","year":"2019","journal-title":"Plasma Sci. Technol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"23880","DOI":"10.1364\/OE.25.023880","article-title":"Tunable Fano resonance based on grating-coupled and graphene-based Otto configuration","volume":"25","author":"Wang","year":"2017","journal-title":"Opt. Express"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1007\/s13320-018-0509-6","article-title":"Refractive Index Sensor Based on Fano Resonances in Plasmonic Waveguide with Dual Side-Coupled Ring Resonators","volume":"8","author":"Zhang","year":"2018","journal-title":"Photonic Sens."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"10907","DOI":"10.1364\/OE.19.010907","article-title":"Fano-type spectral asymmetry and its control for plasmonic metal-insulator-metal stub structures","volume":"19","author":"Piao","year":"2011","journal-title":"Opt. Express"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"18994","DOI":"10.1364\/OE.20.018994","article-title":"Control of Fano asymmetry in plasmon induced transparency and its application to plasmonic waveguide modulator","volume":"20","author":"Piao","year":"2012","journal-title":"Opt. Express"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"185702","DOI":"10.1088\/0957-4484\/26\/18\/185702","article-title":"One-process fabrication of metal hierarchical nanostructures with rich nanogaps for highly-sensitive surface-enhanced Raman scattering","volume":"26","author":"Liu","year":"2015","journal-title":"Nanotechnology"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"037301","DOI":"10.7498\/aps.68.20190054","article-title":"Surface-enhanced Raman scattering effect of a composite structure with gold nano-cubes and gold film separated by Polymethylmethacrylate film","volume":"68","author":"Wang","year":"2019","journal-title":"Acta Phys. Sin."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"845","DOI":"10.1016\/j.snb.2018.02.048","article-title":"Annealed gold nanoshells with highly-dense hotspots for large-area efficient Raman scattering substrates","volume":"262","author":"Yu","year":"2018","journal-title":"Sens. Actuators B Chem."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1866","DOI":"10.1016\/j.rinp.2019.02.002","article-title":"Investigation of surface plasmons in Kretschmann structure loaded with a silver nano-cube","volume":"12","author":"Wang","year":"2019","journal-title":"Results Phys."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"732","DOI":"10.1016\/j.rinp.2018.12.029","article-title":"Theoretical investigation of subwavelength structures fabrication based on multiexposure surface plasmon interference lithography","volume":"12","author":"Wang","year":"2019","journal-title":"Results Phys."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1007\/s11082-019-1759-2","article-title":"Theoretical realization of three-dimensional nanolattice structure fabrication based on high-order waveguide-mode interference and sample rotation","volume":"51","author":"Wang","year":"2019","journal-title":"Opt. Quant. Electron."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1016\/j.optcom.2018.11.083","article-title":"Tunable triple-band graphene refractive index sensor with good angle-polarization tolerance","volume":"436","author":"Liang","year":"2019","journal-title":"Opt. Commun."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"9039","DOI":"10.1364\/OE.26.009039","article-title":"Symmetrical dual D-shape photonic crystal fibers for surface plasmon resonance sensing","volume":"26","author":"Liu","year":"2018","journal-title":"Opt. Express"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"4222","DOI":"10.1039\/C4TC02928C","article-title":"Enhancing refractive index sensing capability with hybrid plasmonic\u2013photonic absorbers","volume":"3","author":"Liu","year":"2015","journal-title":"J. Mater. Chem. C"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"197301","DOI":"10.7498\/aps.67.20180758","article-title":"Refractive index sensor and filter of metal-insulator-metal waveguide based on ring resonator embedded by cross structure","volume":"67","author":"Qi","year":"2018","journal-title":"Acta Phys. Sin."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Cen, C.L., Lin, H., Huang, J., Liang, C.P., Chen, X.F., Tang, Y.J., Yi, Z., Ye, X., Liu, J.W., and Yi, Y.G. (2018). A Tunable Plasmonic Refractive Index Sensor with Nanoring-Strip Graphene Arrays. Sensors, 18.","DOI":"10.3390\/s18124489"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"14227","DOI":"10.1364\/OE.25.014227","article-title":"Mid-infrared surface plasmon resonance sensor based on photonic crystal fibers","volume":"25","author":"Liu","year":"2017","journal-title":"Opt. Express"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"28667","DOI":"10.1364\/OE.23.028667","article-title":"Self-referenced biosensor based on thin dielectric grating combined with thin metal film","volume":"23","author":"Abutoama","year":"2015","journal-title":"Opt. Express"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"4600309","DOI":"10.1109\/JSTQE.2016.2520878","article-title":"Angular and intensity modes self-referenced refractive index sensor based on thin dielectric grating combined with thin metal film","volume":"23","author":"Abutoama","year":"2017","journal-title":"IEEE J. Sel. Top. Quant."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"5703","DOI":"10.1364\/AO.46.005703","article-title":"Grating-coupled transmission-type surface plasmon resonance sensors based on dielectric and metallic gratings","volume":"46","author":"Byun","year":"2007","journal-title":"Appl. Opt."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/S0925-4005(98)00322-0","article-title":"Surface plasmon resonance sensors based on diffraction gratings and prism couplers: Sensitivity comparison","volume":"54","author":"Homola","year":"1999","journal-title":"Sens. Actuators B-Chem."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"024202","DOI":"10.1088\/1674-1056\/26\/2\/024202","article-title":"Theoretical investigation of hierarchical sub-wavelength photonic structures fabricated using high-order waveguide-mode interference lithograph","volume":"26","author":"Wang","year":"2017","journal-title":"Chin. Phys. B"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1016\/S0925-4005(98)00321-9","article-title":"Surface plasmon resonance sensors: review","volume":"54","author":"Homola","year":"1999","journal-title":"Sens. Actuators B-Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1016\/S0925-4005(97)00290-6","article-title":"A surface plasmon resonance sensor probe based on retro-reflection","volume":"45","author":"Colin","year":"1997","journal-title":"Sens. Actuators B-Chem."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"2757","DOI":"10.1063\/1.1616205","article-title":"Free-space coupling of a light beam into a symmetrical metal-cladding optical waveguide","volume":"83","author":"Li","year":"2003","journal-title":"Appl. Phys. Lett."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1007\/s11082-018-1601-2","article-title":"Theoretical study of multiexposure zeroth-order waveguide mode interference lithography","volume":"50","author":"Pang","year":"2018","journal-title":"Opt. Quant. Electron."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"105029","DOI":"10.1063\/1.5043469","article-title":"Investigation of wide-range refractive index sensor based on asymmetric metalcladding dielectric waveguide structure","volume":"8","author":"Wang","year":"2018","journal-title":"AIP Adv."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"396","DOI":"10.1364\/AO.13.000396","article-title":"Metal-Clad Optical Waveguides: Analytical and Experimental Study","volume":"13","author":"Kaminow","year":"1974","journal-title":"Appl. Opt."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"274","DOI":"10.1364\/JOSA.64.000274","article-title":"Metal-clad planar dielectric waveguide for integrated optics","volume":"64","author":"Polky","year":"1974","journal-title":"J. Opt. Soc. Am."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"6800509","DOI":"10.1109\/JPHOT.2016.2640660","article-title":"Symmetrical metal cladding waveguide for absorption sensing and its sensitivity analysis","volume":"9","author":"Zhou","year":"2017","journal-title":"IEEE Photonics J."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"4842","DOI":"10.1364\/OE.14.004842","article-title":"Design optimization of nano-grating surface plasmon resonance sensors","volume":"14","author":"Yoon","year":"2006","journal-title":"Opt. Express"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"2560","DOI":"10.1038\/s41598-018-20952-7","article-title":"Characteristics of multiple Fano resonances in waveguide-coupled surface plasmon resonance sensors based on waveguide theory","volume":"8","author":"Yang","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"158","DOI":"10.1016\/j.snb.2006.09.014","article-title":"Recent advancements in surface plasmon resonance immunosensors for detection of small molecules of biomedical, food and environmental interest","volume":"121","author":"Shankaran","year":"2007","journal-title":"Sens. Actuators B-Chem."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/5\/1187\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:37:17Z","timestamp":1760186237000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/5\/1187"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,3,8]]},"references-count":45,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2019,3]]}},"alternative-id":["s19051187"],"URL":"https:\/\/doi.org\/10.3390\/s19051187","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,3,8]]}}}