Tunable microwave frequency synthesis with optically-derived spectral purity

Tunable microwave frequency synthesis with optically-derived spectral purity | 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 Tunable microwave frequency synthesis with optically-derived spectral purity James Greenberg, Scott Egbert, William McGrew, Brendan Heffernan, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8904294/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Microwave synthesizers are central to test and measurement systems across applications including wireless communications, radar, spectroscopy, and time and frequency metrology. State-of-the-art microwave sources, however, are fundamentally constrained by trade-offs between frequency tunability and spectral purity. Electro-optic frequency division (eOFD) is an emerging technique for dividing down the purity of optical sources to the microwave domain. Previously reported eOFD-based synthesizers generally have limited tunability due to feedback stabilization requirements. Here we demonstrate a feed-forward eOFD architecture in which the frequency tunability of a microwave source is preserved while optical spectral purity is divided through feed-forward cancellation, without any downstream electronic frequency synthesis. By canceling the phase noise of the microwave source without feedback, this eOFD approach removes loop bandwidth and source noise constraints observed in prior eOFD architectures. We achieve octave-spanning tunability, including the entire X-band, with phase noise below -140 dBc/Hz at kilohertz offsets and a high-frequency noise floor between -155 dBc/Hz and -145 dBc/Hz for carrier frequencies from 8 to 16 GHz. This performance corresponds to single-femtosecond integrated timing jitter, enabling, to our knowledge, the first demonstration of coherent, optically referenced microwave synthesis under wide tuning with this level of spectral purity. Physical sciences/Optics and photonics/Applied optics Physical sciences/Physics/Applied physics Physical sciences/Physics/Techniques and instrumentation electro-optical frequency division feed-forward microwave phase noise Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Under Review 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-8904294","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":602028540,"identity":"5ba2ac18-ae57-4e35-94b1-68a058efae86","order_by":0,"name":"James Greenberg","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwElEQVRIiWNgGAWjYBACxgYwdYCBn5lkLZLNJFp2gMHgALFqmfvXPnzwcccdOePj3GkffjDYyek2EHLYjOfGhjPPPDM2O8y7eWYPQ7KxGSHrGGccY5PmbTucuA2ohYGH4UDiNiK0sP/+23a4fnMz72bGP0Rp6W9jY2ZsO5xgwMy7mZlIW9iYJXvbnhnOADqMWcaACL8Y9h9j/PCz7Y48f//ZzYxvKuzkCGuZkYDMNSCgHATk+QkZOgpGwSgYBaMAAHEvQ7mo36+jAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0001-7731-257X","institution":"IMRA America, Inc.","correspondingAuthor":true,"prefix":"","firstName":"James","middleName":"","lastName":"Greenberg","suffix":""},{"id":602028541,"identity":"eb40e29a-516a-46a6-8061-86a37d2a3597","order_by":1,"name":"Scott Egbert","email":"","orcid":"","institution":"IMRA America, Inc.","correspondingAuthor":false,"prefix":"","firstName":"Scott","middleName":"","lastName":"Egbert","suffix":""},{"id":602028542,"identity":"a0b1528d-c4b7-437c-87cb-912657348cd5","order_by":2,"name":"William McGrew","email":"","orcid":"","institution":"IMRA America, Inc.","correspondingAuthor":false,"prefix":"","firstName":"William","middleName":"","lastName":"McGrew","suffix":""},{"id":602028543,"identity":"8577828b-9e10-4dbc-813a-9fb0b92d2290","order_by":3,"name":"Brendan Heffernan","email":"","orcid":"","institution":"IMRA America, Inc.","correspondingAuthor":false,"prefix":"","firstName":"Brendan","middleName":"","lastName":"Heffernan","suffix":""},{"id":602028544,"identity":"32dcf82f-2553-49e2-951d-071682afbe4c","order_by":4,"name":"Antoine Rolland","email":"","orcid":"https://orcid.org/0000-0002-3214-0062","institution":"IMRA America, Inc.","correspondingAuthor":false,"prefix":"","firstName":"Antoine","middleName":"","lastName":"Rolland","suffix":""}],"badges":[],"createdAt":"2026-02-17 21:05:34","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8904294/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8904294/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104780884,"identity":"c5d441a7-6dcf-43ca-83ef-e9ba64be0fc8","added_by":"auto","created_at":"2026-03-17 07:54:12","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":967390,"visible":true,"origin":"","legend":"Article File","description":"","filename":"Tunablemicrowavefrequencysynthesiswithopticallyderivedspectralpurity.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8904294/v1_covered_9e85263e-fe59-42fe-bf52-74ffdfa72fff.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Tunable microwave frequency synthesis with optically-derived spectral purity","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"electro-optical frequency division, feed-forward, microwave, phase noise","lastPublishedDoi":"10.21203/rs.3.rs-8904294/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8904294/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Microwave synthesizers are central to test and measurement systems across applications including wireless communications, radar, spectroscopy, and time and frequency metrology. State-of-the-art microwave sources, however, are fundamentally constrained by trade-offs between frequency tunability and spectral purity. Electro-optic frequency division (eOFD) is an emerging technique for dividing down the purity of optical sources to the microwave domain. Previously reported eOFD-based synthesizers generally have limited tunability due to feedback stabilization requirements. Here we demonstrate a feed-forward eOFD architecture in which the frequency tunability of a microwave source is preserved while optical spectral purity is divided through feed-forward cancellation, without any downstream electronic frequency synthesis. By canceling the phase noise of the microwave source without feedback, this eOFD approach removes loop bandwidth and source noise constraints observed in prior eOFD architectures. We achieve octave-spanning tunability, including the entire X-band, with phase noise below -140 dBc/Hz at kilohertz offsets and a high-frequency noise floor between -155 dBc/Hz and -145 dBc/Hz for carrier frequencies from 8 to 16 GHz. 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