Group index matching for widely tuned SPDC processes in singly poled LNOI waveguide

Group index matching for widely tuned SPDC processes in singly poled LNOI waveguide | 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 Research Article Group index matching for widely tuned SPDC processes in singly poled LNOI waveguide Muskan Arora, Pranav Chokkara, Jasleen Lugani This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8935707/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract We demonstrate the importance of group index engineering and appropriate poling in lithium niobate on insulator (LNOI) waveguide for enabling widely tuned spontaneous parametric downconversion (SPDC) processes.We show that asymmetric and symmetric group index matching (AGIM and SGIM) conditions in such strongly dispersive waveguides allow for phase-matching a wide range of SPDC processes with tunable spectral properties of output photons by changing just the pump wavelength. Condsidering an x-cut LNOI waveguide geometry, we obtain a large pump wavelength tuning range (∼536 nm for AGIM and (∼625 nm for SGIM), thereby facilitating the generation of widely tuned downconverted photons in a singly poled waveguide device. The resultant photon pairs slowly span different wavelength bands, covering NIR and MIR regions, which are important for various quantum information tasks. We also analyze the effect of different waveguide cross-sections on group index engineering capabilities and their influence on the properties of the generated quantum light. The reported work highlights the significance of dispersion properties of the non-linear waveguides and their role in building compact and tunable quantum light sources which can simultaneously cater to a wide variety of quantum optical tasks. Tunable photon pair source Integrated photonics Non-linear waveguides SPDC Lithium niobate Quantum light generation Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 18 Mar, 2026 Reviews received at journal 18 Mar, 2026 Reviews received at journal 17 Mar, 2026 Reviews received at journal 16 Mar, 2026 Reviewers agreed at journal 27 Feb, 2026 Reviewers agreed at journal 27 Feb, 2026 Reviewers agreed at journal 25 Feb, 2026 Reviewers invited by journal 25 Feb, 2026 Editor assigned by journal 23 Feb, 2026 Submission checks completed at journal 23 Feb, 2026 First submitted to journal 21 Feb, 2026 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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