{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T23:34:00Z","timestamp":1773272040918,"version":"3.50.1"},"reference-count":37,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2021,11,9]],"date-time":"2021-11-09T00:00:00Z","timestamp":1636416000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001870","name":"Foundation for Polish Science","doi-asserted-by":"publisher","award":["POIR.04.04.00-00-14D6\/18-01"],"award-info":[{"award-number":["POIR.04.04.00-00-14D6\/18-01"]}],"id":[{"id":"10.13039\/501100001870","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004281","name":"National Science Center","doi-asserted-by":"publisher","award":["DEC-2017\/25\/B\/ST7\/02232"],"award-info":[{"award-number":["DEC-2017\/25\/B\/ST7\/02232"]}],"id":[{"id":"10.13039\/501100004281","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this paper, a novel and cost-effective photonic platform based on silica\u2013titania material is discussed. The silica\u2013titania thin films were grown utilizing the sol\u2013gel dip-coating method and characterized with the help of the prism-insertion technique. Afterwards, the mode sensitivity analysis of the silica\u2013titania ridge waveguide is investigated via the finite element method. Silica\u2013titania waveguide systems are highly attractive due to their ease of development, low fabrication cost, low propagation losses and operation in both visible and near-infrared wavelength ranges. Finally, a ring resonator (RR) sensor device was modelled for refractive index sensing applications, offering a sensitivity of 230 nm\/RIU, a figure of merit (FOM) of 418.2 RIU\u22121, and Q-factor of 2247.5 at the improved geometric parameters. We believe that the abovementioned integrated photonics platform is highly suitable for high-performance and economically reasonable optical sensing devices.<\/jats:p>","DOI":"10.3390\/s21227452","type":"journal-article","created":{"date-parts":[[2021,11,9]],"date-time":"2021-11-09T21:39:07Z","timestamp":1636493947000},"page":"7452","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Mode Sensitivity Exploration of Silica\u2013Titania Waveguide for Refractive Index Sensing Applications"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0829-4886","authenticated-orcid":false,"given":"Muhammad A.","family":"Butt","sequence":"first","affiliation":[{"name":"Warsaw University of Technology, Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warszawa, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3606-3516","authenticated-orcid":false,"given":"Andrzej","family":"Ka\u017amierczak","sequence":"additional","affiliation":[{"name":"Warsaw University of Technology, Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warszawa, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9724-5183","authenticated-orcid":false,"given":"Cuma","family":"Tyszkiewicz","sequence":"additional","affiliation":[{"name":"Silesian University of Technology, Department of Optoelectronics, Krzywoustego 2, 44-100 Gliwice, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5436-9212","authenticated-orcid":false,"given":"Pawe\u0142","family":"Karasi\u0144ski","sequence":"additional","affiliation":[{"name":"Silesian University of Technology, Department of Optoelectronics, Krzywoustego 2, 44-100 Gliwice, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2529-8814","authenticated-orcid":false,"given":"Ryszard","family":"Piramidowicz","sequence":"additional","affiliation":[{"name":"Warsaw University of Technology, Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warszawa, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,11,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"114","DOI":"10.1016\/j.talanta.2012.07.043","article-title":"Silica and silica-titania sol-gel materials: Synthesis and analytical application","volume":"102","author":"Morosanova","year":"2012","journal-title":"Talanta"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"497","DOI":"10.1590\/S1516-14392002000400017","article-title":"Synthesis of Titania-Silica Materials by Sol-Gel","volume":"5","author":"Lenza","year":"2002","journal-title":"Mater. Res."},{"key":"ref_3","first-page":"1","article-title":"Low loss silica-titania waveguide films","volume":"2","author":"Jaglarz","year":"2010","journal-title":"Photonics Lett. Pol."},{"key":"ref_4","first-page":"539","article-title":"Efficient, low-cost optical coupling mechnism for TiO2-SiO2 sol-gel derived slab waveguide surface grating coupler sensors","volume":"4","author":"Kazmierczak","year":"2020","journal-title":"Opt. Appl."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"182","DOI":"10.1016\/S0022-3093(99)00534-7","article-title":"Optical and surface properties of inorganic and hybrid organic\u2013inorganic silica\u2013titania sol\u2013gel planar waveguides","volume":"259","author":"Innocenzi","year":"1999","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_6","unstructured":"Karasinski, P., Tyszkiewicz, C., Piramidowicz, R., and Kazmierczak, A. (April, January 29). Development of integrated photonics based on SiO2:TiO2 sol-gel derived waveguide layers:state of the art, perspectives, prospective applications. Proceedings of the SPIE 11364, Integrated Photonics Platforms: Fundamental Research, Manufacturing and Applications, SPIE Photonics Europe, Strasbourg, France."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"557","DOI":"10.1007\/s00339-019-2854-8","article-title":"Deposition of self-healing thin films by the sol\u2013gel method: A review of layer-deposition mechanisms and activation of self-healing mechanisms","volume":"125","author":"Dezfuli","year":"2019","journal-title":"Appl. Phys. A"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"816","DOI":"10.1364\/JOSAB.9.000816","article-title":"Preparation and properties of sol-gel thin films with porphins","volume":"9","author":"Inoue","year":"1992","journal-title":"J. Opt. Soc. Am. B"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"7821","DOI":"10.1364\/AO.398550","article-title":"Ultrashort inverted tapered silicon ridge-to-slot waveguide coupler at 155 \u00b5m and 3392 \u00b5m wavelength","volume":"59","author":"Butt","year":"2020","journal-title":"Appl. Opt."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"381","DOI":"10.1080\/00387010.2013.848897","article-title":"Sol-Gel-Derived Erbium-Activated Silica-Titania and Silica-Hafnia Planar Waveguides for 1.5 \u00b5m Application in C Band of Telecommunication","volume":"47","author":"Bouajaj","year":"2014","journal-title":"Spectrosc. Lett."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Klein, L., Aparicio, M., and Jitianu, A. (2016). Sol-Gel processed lasers and related optical materials. Handbook of Sol-Gel Science and Technology, Springer.","DOI":"10.1007\/978-3-319-19454-7"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"5544","DOI":"10.1016\/j.tsf.2011.02.064","article-title":"Optical rib waveguides based on sol-gel derived silica-titania fims","volume":"519","author":"Karasinski","year":"2011","journal-title":"Thin. Solid Films"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"6588","DOI":"10.1039\/D0TB00681E","article-title":"Vapor-deposited functional polymer thin films in biological applications","volume":"8","author":"Khlyustova","year":"2020","journal-title":"J. Mater. Chem. B"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1007\/s11082-015-0283-2","article-title":"Directional couplers fabricated via a sol\u2013gel route and conventional optical lithography","volume":"48","author":"Tyszkiewicz","year":"2015","journal-title":"Opt. Quantum Electron."},{"key":"ref_15","first-page":"40","article-title":"Rib waveguides based on the sol-gel derived SiO2:TiO2 films","volume":"2","author":"Karasinski","year":"2010","journal-title":"Photonics Lett. Pol."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Chau, Y.-F.C., Chen, K.-H., Chiang, H.-P., Lim, C.M., Huang, H.J., Lai, C.-H., and Kumara, N.T.R.N. (2019). Fabrication and Characterization of a Metallic\u2013Dielectric Nanorod Array by Nanosphere Lithography for Plasmonic Sensing Application. Nanomaterials, 9.","DOI":"10.3390\/nano9121691"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Karasi\u0144ski, P., Ka\u017amierczak, A., Zi\u0119ba, M., Tyszkiewicz, C., Wojtasik, K., and Kielan, P. (2021). Highly Sensitive Sensor Structure Based on Sol-Gel Waveguide Films and Grating Couplers. Electronics, 10.","DOI":"10.3390\/electronics10121389"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"908","DOI":"10.12693\/APhysPolA.122.908","article-title":"Sensing Properties of Four-Layered Planar Waveguides\u2014Theoretical Analysis","volume":"122","author":"Tyszkiewicz","year":"2012","journal-title":"Acta Phys. Pol. A"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Jaglarz, J., Dulian, P., Karasi\u0144ski, P., and Winkowski, P. (2020). Scattering Phenomena in Porous Sol-Gel-Derived Silica Films. Coatings, 10.","DOI":"10.3390\/coatings10060509"},{"key":"ref_20","first-page":"105840","article-title":"Homogeneity of sol-gel derived silica-titania waveguide films\u2014Spectroscopic and AFM studies","volume":"121","author":"Domanowska","year":"2019","journal-title":"Opt. Laser Technol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1218","DOI":"10.1364\/AO.36.001218","article-title":"Evanescent field sensors with periodically segmented waveguides","volume":"36","author":"Weissman","year":"1997","journal-title":"Appl. Opt."},{"key":"ref_22","first-page":"385","article-title":"Mode sensitivity analysis of vertically arranged double hybrid plasmonic waveguide","volume":"14","author":"Butt","year":"2020","journal-title":"Optoelectron. Adv. Mater. Rapid Commun."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/JPHOT.2019.2939088","article-title":"Mode Sensitivity Analysis of Subwavelength Grating Slot Waveguides","volume":"11","author":"Odeh","year":"2019","journal-title":"IEEE Photon. J."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Butt, M.A., Khonina, S.N., and Kazanskiy, N.L. (2020). Device performance of standard strip, slot and hybrid plasmonic \u03bc-ring resonator: A comparative study. Waves Random Complex Media, 1\u201310.","DOI":"10.1080\/17455030.2020.1744769"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"076201","DOI":"10.1088\/1612-202X\/ab8faa","article-title":"A highly sensitive design of subwavelength grating double-slot waveguide microring resonator","volume":"17","author":"Butt","year":"2020","journal-title":"Laser Phys. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1355","DOI":"10.1109\/JSEN.2019.2944391","article-title":"Sensitivity Enhancement of Silicon Strip Waveguide Ring Resonator by Incorporating a Thin Metal Film","volume":"20","author":"Butt","year":"2019","journal-title":"IEEE Sens. J."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"39084","DOI":"10.1364\/OE.404821","article-title":"High-Q titanium dioxide micro-ring resonators for integrated nonlinear photonics","volume":"28","author":"Fu","year":"2020","journal-title":"Opt. Express"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"10078","DOI":"10.1038\/srep10078","article-title":"High Q-factor microring resonator wrapped by the curved waveguide","volume":"5","author":"Cai","year":"2015","journal-title":"Sci. Rep."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1007\/s11082-019-1778-z","article-title":"Designing a high sensitivity hexagonal nano-cavity photonic crystal resonator for the purpose of seawater salinity sensing","volume":"51","author":"Olyaee","year":"2019","journal-title":"Opt. Quantum Electron."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"2182","DOI":"10.1364\/OME.7.002182","article-title":"Fabrication of a high-Q factor ring resonator using LSCVD deposited Si_3N_4 film","volume":"7","author":"Cheng","year":"2017","journal-title":"Opt. Mater. Express"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Kazanskiy, N.L., Khonina, S.N., and Butt, M.A. (2020). Subwavelength Grating Double Slot Waveguide Racetrack Ring Resonator for Refractive Index Sensing Application. Sensors, 20.","DOI":"10.3390\/s20123416"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"8469","DOI":"10.1109\/JSEN.2020.2985840","article-title":"Evanescent Field Ratio Enhancement of a Modified Ridge Waveguide Structure for Methane Gas Sensing Application","volume":"20","author":"Khonina","year":"2020","journal-title":"IEEE Sens. J."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"9723","DOI":"10.1364\/OE.415825","article-title":"Figures of merit for mid-IR evanescent-wave absorption sensors and their simulation by FEM methods","volume":"29","author":"Consani","year":"2021","journal-title":"Opt. Express"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"688","DOI":"10.1021\/acsphotonics.7b00064","article-title":"Refractive Index Sensor Based on Leaky Resonant Scattering of Single Semiconductor Nanowire","volume":"4","author":"Wang","year":"2017","journal-title":"ACS Photon."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"102311M","DOI":"10.1117\/12.2265305","article-title":"Refractive index sensor based on multi-mode plastic optical fiber with long period grating","volume":"10231","author":"Teng","year":"2017","journal-title":"Proc. SPIE"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1039\/B914183A","article-title":"A packaged optical slot-waveguide ring resonator sensor array for multiplex label-free assays in labs-on-chips","volume":"10","author":"Carlborg","year":"2010","journal-title":"Lab Chip"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"500","DOI":"10.1364\/BOE.8.000500","article-title":"Optimized sensitviity of silicon-on-insulator (SOI) strip waveguide resonator sensor","volume":"8","author":"TalebiFard","year":"2017","journal-title":"Biomed. Opt. Express"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/22\/7452\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:28:21Z","timestamp":1760167701000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/22\/7452"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,11,9]]},"references-count":37,"journal-issue":{"issue":"22","published-online":{"date-parts":[[2021,11]]}},"alternative-id":["s21227452"],"URL":"https:\/\/doi.org\/10.3390\/s21227452","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,11,9]]}}}