Ultra-Low-Loss and Highly Sensitive Photonic Crystal Fiber Sensor for Detection of Cu²⁺ and Mg²⁺ Ions in the THz Regime

Ultra-Low-Loss and Highly Sensitive Photonic Crystal Fiber Sensor for Detection of Cu²⁺ and Mg²⁺ Ions in the THz Regime | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Ultra-Low-Loss and Highly Sensitive Photonic Crystal Fiber Sensor for Detection of Cu²⁺ and Mg²⁺ Ions in the THz Regime Md. Motiur Rahman Tareq, Mahbubul Hasan Mehedi, Joy Banik, Md. Sirajul Islam, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9446342/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Industrial growth has significantly increased water contamination by heavy metal ions, necessitating the development of sensitive and low-loss sensing platforms. In this work, a terahertz (THz) photonic crystal fiber (PCF) sensor is numerically proposed for the detection of Cu²⁺ and Mg²⁺ ions using the full-vector finite element method implemented in COMSOL Multiphysics. The sensing performance is analyzed over the 1.0–3.0 THz frequency range in terms of relative sensitivity (RS), effective material loss (EML), confinement loss (CL), and other properties. At the operating frequency of 2.4 THz, optimum sensing performance is achieved for specific ion concentrations. For the Cu²⁺-based configuration, an optimum concentration of 1.46 mol/kg yields a maximum RS of 99.88% with a low EML of 0.00136 cm⁻¹ and an ultra-low CL of 2.66527×10⁻¹⁴ cm⁻¹. Similarly, for the Mg²⁺-based configuration, the optimum concentration of 1.62 mol/kg provides a maximum RS of 99.83% with corresponding EML and CL values of 0.00139 cm⁻¹ and 1.14415×10⁻¹² cm⁻¹, respectively. Additionally, the birefringence (Bi) stabilizes at the order of 10⁻⁴, ensuring efficient power transmission and robust polarization maintenance. Owing to its high sensitivity, ultra-low loss, and structurally simple design, the proposed PCF sensor is well suited for practical heavy metal ion detection in the THz regime. Terahertz photonic crystal fiber full-vector finite element method relative sensitivity effective material loss confinement loss birefringence Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9446342","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":625202169,"identity":"ff0e2516-2291-44ad-a94d-a992016a5d1a","order_by":0,"name":"Md. 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In this work, a terahertz (THz) photonic crystal fiber (PCF) sensor is numerically proposed for the detection of Cu\u0026sup2;⁺ and Mg\u0026sup2;⁺ ions using the full-vector finite element method implemented in COMSOL Multiphysics. The sensing performance is analyzed over the 1.0\u0026ndash;3.0 THz frequency range in terms of relative sensitivity (RS), effective material loss (EML), confinement loss (CL), and other properties. At the operating frequency of 2.4 THz, optimum sensing performance is achieved for specific ion concentrations. For the Cu\u0026sup2;⁺-based configuration, an optimum concentration of 1.46 mol/kg yields a maximum RS of 99.88% with a low EML of 0.00136 cm⁻\u0026sup1; and an ultra-low CL of 2.66527\u0026times;10⁻\u0026sup1;⁴ cm⁻\u0026sup1;. Similarly, for the Mg\u0026sup2;⁺-based configuration, the optimum concentration of 1.62 mol/kg provides a maximum RS of 99.83% with corresponding EML and CL values of 0.00139 cm⁻\u0026sup1; and 1.14415\u0026times;10⁻\u0026sup1;\u0026sup2; cm⁻\u0026sup1;, respectively. Additionally, the birefringence (Bi) stabilizes at the order of 10⁻⁴, ensuring efficient power transmission and robust polarization maintenance. Owing to its high sensitivity, ultra-low loss, and structurally simple design, the proposed PCF sensor is well suited for practical heavy metal ion detection in the THz regime.\u003c/p\u003e","manuscriptTitle":"Ultra-Low-Loss and Highly Sensitive Photonic Crystal Fiber Sensor for Detection of Cu²⁺ and Mg²⁺ Ions in the THz Regime","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-23 02:34:33","doi":"10.21203/rs.3.rs-9446342/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d469214b-1e3c-4b0b-96a9-388ae3bb9af6","owner":[],"postedDate":"April 23rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-23T02:34:33+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-23 02:34:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9446342","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9446342","identity":"rs-9446342","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}