Ultralow noise microwaves with free-running frequency combs and electrical feedforward

Ultralow noise microwaves with free-running frequency combs and electrical feedforward | 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 Ultralow noise microwaves with free-running frequency combs and electrical feedforward Takuma Nakamura, William Groman, Qing-Xin Ji, Oguzhan Kara, Benjamin Rudin, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8205966/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Apr, 2026 Read the published version in Nature Photonics → Version 1 posted You are reading this latest preprint version Abstract Optically generated microwave signals exhibit some of the lowest phase noise and timing jitter of any microwave-generating technology to date. The success of octave-spanning optical frequency combs in down-converting ultrastable optical frequency references has motivated the development of compact, robust and highly manufacturable optical systems that maintain the ultralow microwave phase noise of their tabletop counterparts. Two-point optical frequency division using chip-scale components and ~1 THz-spanning microcombs has been quite successful, but with stringent requirements on the comb source’s free-running noise and feedback control dynamics. Here we introduce a major simplification of this architecture that replaces feedback control of the frequency comb in favor of electronic feedforward noise cancelation that significantly relaxes the comb requirements. Demonstrated with both a high repetition rate solid-state mode-locked laser and a microcomb, feedforward on a 10 GHz carrier results in more robust operation with phase noise as low as -153 dBc/Hz at offsets ≥10 kHz, femtosecond timing jitter, and elimination of the large “servo bump” noise increase at high offset frequency. The system’s compatibility with a variety of highly manufacturable mode-locked laser designs and its resilience and straightforward implementation represents an important step forward towards a fully chip-scale implementation of optically generated microwaves, with applications in radar, sensing, and position, navigation and timing. Physical sciences/Optics and photonics/Other photonics/Optical metrology Physical sciences/Optics and photonics/Applied optics/Microwave photonics Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Published Journal Publication published 28 Apr, 2026 Read the published version in Nature Photonics → 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-8205966","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":553488535,"identity":"b0254bf5-d876-4d9a-94dd-9ca5d46a0516","order_by":0,"name":"Takuma 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