{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,12]],"date-time":"2026-02-12T14:29:37Z","timestamp":1770906577793,"version":"3.50.1"},"reference-count":20,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2018,5,10]],"date-time":"2018-05-10T00:00:00Z","timestamp":1525910400000},"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 grating-assisted trimodal interferometer biosensor is proposed and numerically analyzed. A long period grating coupler, for adjusting the power between the fundamental mode and the second higher order mode, is investigated, and is shown to act as a conventional directional coupler for adjusting the power between the two arms. The trimodal interferometer can achieve maximal fringe visibility when the powers of the two modes are adjusted to the same value by the grating coupler, which means that a better limit of detection can be expected. In addition, the second higher order mode typically has a larger evanescent tail than the first higher order mode in bimodal interferometers, resulting in a higher sensitivity of the trimodal interferometer. The influence of fabrication tolerances on the performance of the designed interferometer is also investigated. The power difference between the two modes shows inertia to the fill factor of the grating, but high sensitivity to the modulation depth. Finally, a 2050 2\u03c0\/RIU (refractive index unit) sensitivity and 43 dB extinction ratio of the output power are achieved.<\/jats:p>","DOI":"10.3390\/s18051502","type":"journal-article","created":{"date-parts":[[2018,5,11]],"date-time":"2018-05-11T03:42:48Z","timestamp":1526010168000},"page":"1502","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Investigation of Grating-Assisted Trimodal Interferometer Biosensors Based on a Polymer Platform"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4548-5147","authenticated-orcid":false,"given":"Yuxin","family":"Liang","sequence":"first","affiliation":[{"name":"Photonics Research Group, Department of Information and Technology, Ghent University, 9000 Ghent, Belgium"},{"name":"School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian116023, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3114-9479","authenticated-orcid":false,"given":"Mingshan","family":"Zhao","sequence":"additional","affiliation":[{"name":"School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian116023, China"}]},{"given":"Zhenlin","family":"Wu","sequence":"additional","affiliation":[{"name":"School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian116023, China"}]},{"given":"Geert","family":"Morthier","sequence":"additional","affiliation":[{"name":"Photonics Research Group, Department of Information and Technology, Ghent University, 9000 Ghent, Belgium"}]}],"member":"1968","published-online":{"date-parts":[[2018,5,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1016\/j.aca.2008.05.022","article-title":"Sensitive optical biosensors for unlabeled targets: A review","volume":"620","author":"Fan","year":"2008","journal-title":"Anal. Chim. Acta"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1002\/lpor.201100025","article-title":"Integrated optical devices for lab-on-a-chip biosensing applications","volume":"6","author":"Estevez","year":"2012","journal-title":"Laser Photonics Rev."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1109\/50.664067","article-title":"Integrated Optical Mach-Zehnder Biosensor","volume":"16","author":"Luff","year":"1998","journal-title":"J. Lightw. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"7610","DOI":"10.1364\/OE.15.007610","article-title":"Silicon-on-Insulator microring resonator for sensitive and label-free biosensing","volume":"15","author":"Vos","year":"2007","journal-title":"Opt. Express"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"920","DOI":"10.1109\/JPHOT.2012.2200671","article-title":"A Label-Free Optical Biosensor Built on a Low-Cost Polymer Platform","volume":"4","author":"Wang","year":"2012","journal-title":"IEEE Photonics J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/JPHOT.2016.2544641","article-title":"Fabrication and Characterization of High-Optical-Quality-Factor Hybrid Polymer Microring Resonators Operating at Very Near Infrared Wavelengths","volume":"8","author":"Morarescu","year":"2016","journal-title":"IEEE Photonics J."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"3724","DOI":"10.1364\/BOE.6.003724","article-title":"Handheld imaging photonic crystal biosensor for multiplexed, label-free protein detection","volume":"6","author":"Jahns","year":"2015","journal-title":"Biomed. Opt. Express"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"12166","DOI":"10.1364\/OE.24.012166","article-title":"Biosensor architecture for enhanced disease diagnostics: Lab-in-a-photonic-crystal","volume":"24","author":"Feng","year":"2016","journal-title":"Opt. Express"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"5859","DOI":"10.1364\/OE.21.005859","article-title":"Plasmonic interferometers for label-free multiplexed sensing","volume":"21","author":"Gao","year":"2013","journal-title":"Opt. Express"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"9561","DOI":"10.1364\/OE.18.009561","article-title":"A multi-functional plasmonic biosensor","volume":"18","author":"Chang","year":"2010","journal-title":"Opt. Express"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"6363","DOI":"10.1364\/OL.39.006363","article-title":"High-sensitivity optical biosensor based on cascaded Mach-Zehnder interferometer and ring resonator using Vernier effect","volume":"39","author":"Jiang","year":"2014","journal-title":"Opt. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"4200","DOI":"10.1109\/JLT.2005.859435","article-title":"A Novel Mach-Zehnder Interferometer Based on Dual-ARROW Structures for Sensing Applications","volume":"23","author":"Hsu","year":"2005","journal-title":"J. Lightw. Technol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2378","DOI":"10.1364\/OL.29.002378","article-title":"Highly sensitive differential phase-sensitive surface plasmon resonance biosensor based on the Mach\u2013Zehnder configuration","volume":"29","author":"Wu","year":"2004","journal-title":"Opt. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2640","DOI":"10.1364\/OE.20.002640","article-title":"Thermal independent Silicon-Nitride slot waveguide biosensor with high sensitivity","volume":"20","author":"Tu","year":"2012","journal-title":"Opt. Express"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1926","DOI":"10.1109\/JLT.2011.2150734","article-title":"Integrated Bimodal Waveguide Interferometric Biosensor for Label-Free Analysis","volume":"29","author":"Zinoviev","year":"2011","journal-title":"J. Lightw. Technol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"32344","DOI":"10.1364\/OE.22.032344","article-title":"Sensitivity and design of grating-assisted bimodal interferometers for integrated optical biosensing","volume":"22","author":"Bruck","year":"2014","journal-title":"Opt. Express"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"27910","DOI":"10.1364\/OE.22.027910","article-title":"Single-channel Mach-Zehnder interferometric biochemical sensor based on two-lateral-mode spiral waveguide","volume":"22","author":"Liu","year":"2014","journal-title":"Opt. Express"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"11985","DOI":"10.1364\/OE.23.011985","article-title":"Study of a low-cost trimodal polymer waveguide for interferometric optical biosensors","volume":"23","author":"Ramirez","year":"2015","journal-title":"Opt. Express"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1339","DOI":"10.1002\/1521-4095(20021002)14:19<1339::AID-ADMA1339>3.0.CO;2-O","article-title":"Polymer-based optical waveguides: Materials, processing, and devices","volume":"14","author":"Ma","year":"2002","journal-title":"Adv. Mater."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1032","DOI":"10.1364\/JOSAB.26.001032","article-title":"Design guidelines for optical resonator biochemical sensors","volume":"26","author":"Hu","year":"2009","journal-title":"J. Opt. Soc. Am. B"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/5\/1502\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:04:08Z","timestamp":1760195048000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/18\/5\/1502"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,5,10]]},"references-count":20,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2018,5]]}},"alternative-id":["s18051502"],"URL":"https:\/\/doi.org\/10.3390\/s18051502","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,5,10]]}}}