Visible-frequency long-distance subwavelength focusing via surface plasmon hyperbolic polaritons (SPHPs)

Visible-frequency long-distance subwavelength focusing via surface plasmon hyperbolic polaritons (SPHPs) | 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 Visible-frequency long-distance subwavelength focusing via surface plasmon hyperbolic polaritons (SPHPs) Zhengjun Zhang, Jianqiao Zhao, Yuxin Zhang, Xiaotian Xue, Haodong Zhong, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9015011/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 Hyperbolic polaritons offer a promising approach for subwavelength light confinement and manipulation. While extensively explored across mid-infrared to terahertz bands, achieving long distance focusing at visible frequency remains challenging due to the trade-off between long propagation and strong compression. In this work, we demonstrate a mode-selection strategy and experimental approach to achieve long-distance subwavelength in-plane focusing at visible frequency. By integrating an Au metastructure with the natural hyperbolic material MoOCl2, we convert surface plasmon polaritons (SPPs) into surface plasmon hyperbolic polaritons (SPHPs), enabling selective excitation and focusing of the low-momentum (low-k) mode in the hyperbolic material. Furthermore, by modulating the thickness of the MoOCl2 layer, we leverage the intrinsic high-k component to synergistically enhance both long propagation distance and strong field compression. Using transmission-mode scanning near-field optical microscopy (SNOM) and quantitative methods, we demonstrate a focal length of 2.5λ and a focal spot with a full width at half maximum (FWHM) of λ/5 under 633 nm excitation, accompanied by a three-fold energy enhancement. This visible-band long-focus system offers significant potential for non-contact nanoscale probing, integrated photonics, and optical interconnects. The proposed mode-selection methodology provides a versatile design paradigm for coupling hyperbolic polaritons with multiple plasmonic excitations, paving the way for advanced applications in photonic information processing. Physical sciences/Materials science/Materials for optics/Nanophotonics and plasmonics Physical sciences/Nanoscience and technology/Nanoscale materials/Two-dimensional materials Physical sciences/Optics and photonics/Optical materials and structures/Metamaterials Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryMaterialsforVisiblefrequencylongdistancesubwavelengthfocusingviaSPHPs.pdf Supplementary Materials for Visible-frequency long-distance subwavelength focusing via surface plasmon hyperbolic polaritons (SPHPs) 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-9015011","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":605196663,"identity":"28f85266-015a-4228-9ece-76e40fbc3207","order_by":0,"name":"Zhengjun 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While extensively explored across mid-infrared to terahertz bands, achieving long distance focusing at visible frequency remains challenging due to the trade-off between long propagation and strong compression. In this work, we demonstrate a mode-selection strategy and experimental approach to achieve long-distance subwavelength in-plane focusing at visible frequency. By integrating an Au metastructure with the natural hyperbolic material MoOCl2, we convert surface plasmon polaritons (SPPs) into surface plasmon hyperbolic polaritons (SPHPs), enabling selective excitation and focusing of the low-momentum (low-k) mode in the hyperbolic material. Furthermore, by modulating the thickness of the MoOCl2 layer, we leverage the intrinsic high-k component to synergistically enhance both long propagation distance and strong field compression. Using transmission-mode scanning near-field optical microscopy (SNOM) and quantitative methods, we demonstrate a focal length of 2.5λ and a focal spot with a full width at half maximum (FWHM) of λ/5 under 633 nm excitation, accompanied by a three-fold energy enhancement. This visible-band long-focus system offers significant potential for non-contact nanoscale probing, integrated photonics, and optical interconnects. 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