Gouy-phase engineered space-time singularities in second harmonic generation

Gouy-phase engineered space-time singularities in second harmonic generation | 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 Gouy-phase engineered space-time singularities in second harmonic generation Jintao Fan, XueChen Gao, Youjian Yi, XiuYu Yao, Wei Chen, Ping Zhu, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9367941/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 Space-time singularities represent points where the local structure of a wave field becomes locally undefined, and are central to phenomena ranging from fluid dynamics to cosmology. In optics, spatiotemporal optical vortices (STOVs) provide a versatile setting in which to study such singularities, but their controlled manipulation during nonlinear frequency conversion has remained elusive. Here we show that the evolution of STOV singularities in second-harmonic generation can be continuously engineered through spatial Gouy-phase control. In a 4f system, translating a thin nonlinear crystal about the Fourier plane imposes a tunable Gouy phase that governs the orientation, splitting, and trajectories of singularities in the second-harmonic field. A Hermite-Gaussian modal description identifies Gouy-phase-dependent mechanism underlying these dynamics, in agreement with spatiotemporal interferometry measurements. Beyond integer-order inputs, fractional-order inputs (l=0.5) result in a distinct regime in which Gouy-phase bias drives topological reconfiguration and directional energy redistribution. Our results establish the Gouy phase as a simple yet powerful control knob for space-time singularities, opening new opportunities for structured-light engineering in nonlinear and ultrafast photonics. Physical sciences/Optics and photonics/Optical physics/Nonlinear optics Physical sciences/Optics and photonics/Optical techniques/Optical manipulation and tweezers Second harmonic generation spatiotemporal optical vortices Gouy phase shift Full Text Additional Declarations There is NO Competing Interest. Supplementary Files Supplementaryinformationfinal.docx Supplementary Materials 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. 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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-9367941","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":620277218,"identity":"2541b546-52b9-480b-b47f-7bc477df508d","order_by":0,"name":"Jintao 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