{"paper_id":"232f61dc-cc85-4687-a36f-8f147258f774","body_text":"High Numerical Aperture Metalens for the Deep Ultraviolet | 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 High Numerical Aperture Metalens for the Deep Ultraviolet Omar A. M. Abdelraouf, Chee Leng Lay, Haoyu Ge, Ziyu Zhou, Youpeng Zhang, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7787509/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 Deep-ultraviolet (DUV) light plays a pivotal role in advanced applications such as nanofabrication, biomedical imaging, and emerging photonic devices development. However, the lack of compact, high-performance optical components in this spectral range has hindered progress. Here, we demonstrate an aluminum nitride (AlN) metalens experimentally with a record high numerical aperture (HNA) from 0.9 to 0.7, operating at a DUV wavelength of 266 nm. Besides the optical measurement of the HNA metalens achieving a diffraction-limited focusing, we show that lithographic direct writing is not only employing the HNA metalens for nanofabrication but a universal and practical way to characterize the HNA DUV metalens especially considering the difficulties to build up a wideband HNA optical characterization system in this wavelength range. For applications, the HNA AlN metalens has been integrated in a confocal PL system and enables compact nanoscale spectroscopic imaging. This breakthrough establishes AlN metalenses as a transformative platform and practical solution for high-resolution DUV applications, bridging the gap between scalable metaoptics and next-generation photonic technologies in the deep-ultraviolet regime. metalens deep-ultraviolet aluminum nitride high numerical aperture laser nanofabrication sub-200 nm resolution DUV metaoptics direct laser writing nanoscale imaging Full Text Additional Declarations The authors declare no competing interests. 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-7787509\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":true,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":525074911,\"identity\":\"45bef940-6a89-4773-abb9-c8c30bb0c54b\",\"order_by\":0,\"name\":\"Omar A. M. Abdelraouf\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Omar\",\"middleName\":\"A. 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