On-chip, inverse-designed active wavelength division multiplexer at THz frequencies

On-chip, inverse-designed active wavelength division multiplexer at THz frequencies | 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 On-chip, inverse-designed active wavelength division multiplexer at THz frequencies Valerio Digiorgio, Urban Senica, Paolo Micheletti, Mattias Beck, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5699333/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 19 Aug, 2025 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract The development of photonic integrated components for terahertz has become an active and growing research field. Despite its numerous applications, several challenges are still present in hardware design. We demonstrate an on-chip active wavelength division multiplexer (WDM) operating at THz frequencies. The WDM architecture is based on an inverse design topology optimization, which is applied in this case to the active quantum cascade heterostructure material embedded within a polymer in a planarized double metal cavity. Such an approach enables the fabrication of a strongly subwavelength device, with a normalized volume of only (V/λ) 3 ≃ 0.5. The WDM input is integrated with a THz quantum cascade laser frequency comb, providing three broadband output ports, ranging from 2.2 THz to 3.2 THz, with ≈ 330 GHz bandwidth and a maximum crosstalk of -6 dB. The three ports are outcoupled via integrated broadband patch array antennas with surface emission. Such a device can be also function as a stand-alone element, unlocking complex on-chip signal processing in the THz range. Physical sciences/Optics and photonics/Applied optics/Integrated optics Physical sciences/Optics and photonics/Optical physics/Terahertz optics Physical sciences/Optics and photonics/Lasers, LEDs and light sources/Quantum cascade lasers Integrated optics Inverse design Frequency combs Terahertz lasers Multiplexers Optical waveguides Antennas Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SuppInvDesWDM.pdf Supplementary Material for On-chip, inverse-designed active wavelength division multiplexer at THz frequencies Cite Share Download PDF Status: Published Journal Publication published 19 Aug, 2025 Read the published version in Nature Communications → 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. 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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-5699333","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":407875180,"identity":"8b662bf7-01fe-46aa-9747-beff3ca979dc","order_by":0,"name":"Valerio 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