Exploring the feedback limits of quantum dot lasers for isolator-free photonic integrated circuits

Exploring the feedback limits of quantum dot lasers for isolator-free photonic integrated circuits | 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 Exploring the feedback limits of quantum dot lasers for isolator-free photonic integrated circuits Yating Wan, Ying Shi, Bozhang Dong, Xiangpeng Ou, Artem Prokoshin, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7751496/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Jan, 2026 Read the published version in Light: Science & Applications → Version 1 posted 7 You are reading this latest preprint version Abstract Reflections from on-chip components pose significant challenges to stable laser operation in photonic integrated circuits (PICs). Quantum dot (QD) lasers, with low linewidth enhancement factors and high damping rates, are promising for isolator-free integration, yet earlier feedback studies were capped near -10 dB feedback and never reached coherence collapse (CC). As a result, one could only conclude that QD lasers tolerate feedback up to –10 dB, leaving open whether they remain reliable in practical PICs where lower coupling losses allow much stronger feedback. Here, we optimized QD lasers through advanced epitaxial growth and fabrication and developed a setup that delivers feedback up to 0 dB. Under these conditions, we observed CC at -6.7 dB (21.4% feedback), extending the feedback tolerance by tens of decibels beyond quantum well (QW) lasers. We further demonstrated penalty-free 10 Gbps operation, robust thermal stability with ±0.5 dB drift across 15–45 °C, >100 h continuous testing, and ~±0.3 dB reproducibility across devices. Modeling indicates even stronger tolerance in realistic PIC cavities, and benchmarking shows our device rivals hybrid DFB–resonator platforms while outperforming other QW, QD, and VCSEL lasers. Together, this work provides the most comprehensive assessment of QD laser feedback tolerance to date and establishes practical design rules for isolator-free PICs. Physical sciences/Optics and photonics/Lasers, LEDs and light sources/Semiconductor lasers Physical sciences/Optics and photonics/Optical materials and structures/Quantum dots Physical sciences/Optics and photonics/Applied optics/Integrated optics Full Text Additional Declarations There is a conflict of interest Supplementary Files SupplementaryInformation.docx Supplementary Information for: Exploring the feedback limits of quantum dot lasers for isolator-free photonic integrated circuits Cite Share Download PDF Status: Published Journal Publication published 30 Jan, 2026 Read the published version in Light: Science & Applications → Version 1 posted Reviewer # 2 agreed at journal 12 Oct, 2025 Review # 1 received at journal 12 Oct, 2025 Reviewer # 1 agreed at journal 12 Oct, 2025 Reviewers invited by journal 09 Oct, 2025 Submission checks completed at journal 09 Oct, 2025 Editor assigned by journal 30 Sep, 2025 First submitted to journal 30 Sep, 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-7751496","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":526892124,"identity":"2fbe27a6-aac4-4b67-b9aa-cef95293ea62","order_by":0,"name":"Yating 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Quantum dot (QD) lasers, with low linewidth enhancement factors and high damping rates, are promising for isolator-free integration, yet earlier feedback studies were capped near -10 dB feedback and never reached coherence collapse (CC). As a result, one could only conclude that QD lasers tolerate feedback up to –10 dB, leaving open whether they remain reliable in practical PICs where lower coupling losses allow much stronger feedback. Here, we optimized QD lasers through advanced epitaxial growth and fabrication and developed a setup that delivers feedback up to 0 dB. Under these conditions, we observed CC at -6.7 dB (21.4% feedback), extending the feedback tolerance by tens of decibels beyond quantum well (QW) lasers. We further demonstrated penalty-free 10 Gbps operation, robust thermal stability with ±0.5 dB drift across 15–45 °C, \u003e100 h continuous testing, and ~±0.3 dB reproducibility across devices. Modeling indicates even stronger tolerance in realistic PIC cavities, and benchmarking shows our device rivals hybrid DFB–resonator platforms while outperforming other QW, QD, and VCSEL lasers. Together, this work provides the most comprehensive assessment of QD laser feedback tolerance to date and establishes practical design rules for isolator-free PICs.","manuscriptTitle":"Exploring the feedback limits of quantum dot lasers for isolator-free photonic integrated circuits","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-22 09:41:09","doi":"10.21203/rs.3.rs-7751496/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"This content is not available.","date":"2025-10-13T01:59:01+00:00","index":2,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2025-10-12T21:49:31+00:00","index":1,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2025-10-12T21:47:59+00:00","index":1,"fulltext":"This content is not available."},{"type":"reviewersInvited","content":"","date":"2025-10-09T06:24:49+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-09T06:17:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-09-30T12:29:22+00:00","index":"","fulltext":""},{"type":"submitted","content":"Light: Science \u0026 Applications","date":"2025-09-30T12:29:21+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"light-science-and-applications","isNatureJournal":false,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"lsa","sideBox":"Learn more about [Light: Science \u0026 Applications](http://www.nature.com/lsa/)","snPcode":"41377","submissionUrl":"https://mts-lsa.nature.com/","title":"Light: Science \u0026 Applications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3a3fe249-5f3e-4f2c-ac83-33a23d24d54f","owner":[],"postedDate":"October 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":56002502,"name":"Physical sciences/Optics and photonics/Lasers, LEDs and light sources/Semiconductor lasers"},{"id":56002503,"name":"Physical sciences/Optics and photonics/Optical materials and structures/Quantum dots"},{"id":56002504,"name":"Physical sciences/Optics and photonics/Applied optics/Integrated optics"}],"tags":[],"updatedAt":"2026-02-03T10:26:32+00:00","versionOfRecord":{"articleIdentity":"rs-7751496","link":"https://doi.org/10.1038/s41377-026-02185-w","journal":{"identity":"light-science-and-applications","isVorOnly":false,"title":"Light: Science \u0026 Applications"},"publishedOn":"2026-01-30 05:00:00","publishedOnDateReadable":"January 30th, 2026"},"versionCreatedAt":"2025-10-22 09:41:09","video":"","vorDoi":"10.1038/s41377-026-02185-w","vorDoiUrl":"https://doi.org/10.1038/s41377-026-02185-w","workflowStages":[]},"version":"v1","identity":"rs-7751496","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7751496","identity":"rs-7751496","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}