{"paper_id":"4b498bf2-c509-4ccf-acf5-30b4ec3f96ca","body_text":"Mode-tunable photonic topological insulator metasurface enabling leaky-wave antenna operation | 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 Article Mode-tunable photonic topological insulator metasurface enabling leaky-wave antenna operation Vinothan Vaheesan, Kevin Mitchell, Daniel Trussler, Aleksandr Bystrov, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9227051/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The inherent properties of photonic topological insulators forbid leaky wave operation suitable for communication and sensing systems. We demonstrate a mode-tunable leaky-wave photonic topological insulator (PTI) metasurface enabled through controlled dispersion engineering. By introducing slots of defined length (op_len) into hexagonal aperture unit cells along the topological interface, the guided-to-leaky wave transition frequency and beam-scanning gradient are systematically tuned. Supercell band-structure analysis and full-wave simulations show that varying op_len (0 mm, 1.5 mm, and 0.7 mm) yields transition frequencies of 20 GHz, 18.5 GHz, and 18 GHz, respectively. At 18 GHz, the radiation gain contrast between guided (op_len = 0 mm, -4.98 dBi) and leaky (op_len = 1.5 mm, 6.50 dBi) states reaches 11.48 dB, corresponding to a 14-fold increase in radiated power. The proposed platform enables seamless, zero-taper transitions between waveguiding and radiative sections, supporting compact photonic integration. Experimental far-field measurements validate the predicted frequency-dependent beam-steering behaviour. This work presents the first experimental demonstration of a mode-tunable PTI metasurface, extending topological photonics beyond robust waveguiding toward multifunctional, beam-steerable metasurfaces for next-generation mmWave communication systems on a compact, scalable, and PCB-compatible platform. Physical sciences/Physics/Electronics, photonics and device physics/Photonic devices Physical sciences/Optics and photonics/Optical materials and structures/Metamaterials Physical sciences/Optics and photonics/Optical materials and structures/Photonic crystals Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Under Review 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. 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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-9227051\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":false,\"archivedVersions\":[],\"articleType\":\"Article\",\"associatedPublications\":[],\"authors\":[{\"id\":632616468,\"identity\":\"a6fc5cdd-aec7-4c0e-817d-b9775e286821\",\"order_by\":0,\"name\":\"Vinothan 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