Lasing of a Cavity Based X-ray Source

Lasing of a Cavity Based X-ray Source | 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 Physical Sciences - Article Lasing of a Cavity Based X-ray Source Patrick Rauer, Immo Bahns, Bertram Friedrich, Sara Casalbuoni, and 29 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7274597/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Jan, 2026 Read the published version in Nature → Version 1 posted You are reading this latest preprint version Abstract Cavity-based X-ray Free Electron Lasers (CBXFELs) promise to transform the field of hard X-ray science by delivering radiation with exceptional brilliance, stability, and full three-dimensional coherence. At the European XFEL, we have realized a proof-of-concept CBXFEL featuring a 132.8 m round-trip hard X-ray cavity using diamond crystals in Bragg reflection. Here, we report lasing with multi-pass gain in an X-ray cavity, marking a major milestone for the field. Our results establish the feasibility of CBXFELs and open the door to next-generation X-ray science requiring unprecedented spectral purity and stability. Physical sciences/Optics and photonics/Lasers, LEDs and light sources/Free-electron lasers Physical sciences/Optics and photonics/Optical physics/X-rays FEL X-ray Cavity Laser High Brilliance Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Published Journal Publication published 28 Jan, 2026 Read the published version in Nature → 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-7274597","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":499072501,"identity":"2c7b2825-432a-418a-9048-cf18c7790b61","order_by":0,"name":"Patrick 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