Coherent control of (non-)Hermitian mode coupling: tunable chirality and exceptional point dynamics in photonic microresonators

Coherent control of (non-)Hermitian mode coupling: tunable chirality and exceptional point dynamics in photonic microresonators | 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 Coherent control of (non-)Hermitian mode coupling: tunable chirality and exceptional point dynamics in photonic microresonators Bülent Aslan, Riccardo Franchi, Stefano Biasi, Salamat Ali, Davide Olivieri, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6420889/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 06 Mar, 2026 Read the published version in Light: Science & Applications → Version 1 posted 16 You are reading this latest preprint version Abstract This work introduces a novel on-chip integrated photonic device, the Dynamically Reconfigurable Unified Microresonator (DRUM), enabling full and dynamic control of Hermitian and non-Hermitian modal coupling between counter-propagating modes in a microresonator. The DRUM consists of a microresonator coupled to two tunable side waveguides, each incorporating a Mach-Zehnder Interferometer and a phase shifter, allowing for independent manipulation of the amplitude and phase of the coupling coefficients. This unique architecture facilitates a continuous and arbitrary transition between diabolic points (DPs) and exceptional points (EPs). We experimentally demonstrate the versatility of the DRUM through several key functionalities: dynamic tuning of the resonance spectral lineshape, coherent suppression of backscattering to achieve an ideal DP, and operation in both Hermitian and non-Hermitian states, enabling continuous chirality tuning and dynamic steering between two EPs. The device achieves a chirality of ± 1 at the EPs, indicating strong directionality in light propagation. The experimental results, supported by a theoretical model based on Temporal Coupled Mode Theory, pave the way for reconfigurable photonic devices that exploit (non-)Hermitian dynamics for advanced functionalities, with potential applications ranging from high-sensitivity sensors to neuromorphic computing. The DRUM overcomes the limitations of previous implementations by offering unprecedented control over the coupling between counter-propagating modes within a single integrated device. Physical sciences/Optics and photonics/Applied optics/Integrated optics Physical sciences/Optics and photonics/Applied optics/Optoelectronic devices and components Full Text Additional Declarations There is no conflict of interest Cite Share Download PDF Status: Published Journal Publication published 06 Mar, 2026 Read the published version in Light: Science & Applications → Version 1 posted Editorial decision: revise 02 Sep, 2025 Review # 5 received at journal 08 Aug, 2025 Reviewer # 6 agreed at journal 07 Aug, 2025 Review # 3 received at journal 29 Jul, 2025 Reviewer # 5 agreed at journal 09 Jul, 2025 Review # 4 received at journal 09 Jul, 2025 Reviewer # 4 agreed at journal 04 Jul, 2025 Review # 2 received at journal 27 May, 2025 Reviewer # 3 agreed at journal 01 May, 2025 Reviewer # 2 agreed at journal 27 Apr, 2025 Reviewer # 1 agreed at journal 27 Apr, 2025 Reviewers invited by journal 23 Apr, 2025 Submission checks completed at journal 19 Apr, 2025 First submitted to journal 16 Apr, 2025 Unknown event 16 Apr, 2025 Editor assigned by journal 10 Apr, 2025 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-6420889","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":446924010,"identity":"dde390ba-6ebd-4f15-86a1-47fc01605145","order_by":0,"name":"Bülent Aslan","email":"","orcid":"https://orcid.org/0009-0009-7125-7202","institution":"Nanoscience Laboratory, Department of Physics, University of Trento, 38123 Povo, Italy","correspondingAuthor":false,"prefix":"","firstName":"Bülent","middleName":"","lastName":"Aslan","suffix":""},{"id":446924011,"identity":"f636ce23-1d14-44ba-8e29-6c5a0db1833a","order_by":1,"name":"Riccardo 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