Parts-per-trillion level microscale mode Vernier photoacoustic spectroscopy for all-fiber gas sensing

Parts-per-trillion level microscale mode Vernier photoacoustic spectroscopy for all-fiber gas sensing | 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 Parts-per-trillion level microscale mode Vernier photoacoustic spectroscopy for all-fiber gas sensing Wenjun Ni, Zhongke Zhao, Chuanwen Qian, Yanzhi Lv, Georges Humbert, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9451197/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Ultra-sensitive miniaturized fiber-optic gas sensors are urgently needed for trace gas detection in semiconductor manufacturing, environmental monitoring, and industrial safety. However, existing photoacoustic spectroscopy (PAS) technologies face an inherent trade-off between device size and detection sensitivity. Here, we propose mode Vernier photoacoustic spectroscopy (MV-PAS) to break this bottleneck, based on a dual-mode anti-resonant Bragg hollow-core fiber (BHCF) integrated with a two-photon polymerized square-ring cantilever (SRC). The device constitutes a mode Vernier effect (MVE)-enhanced Fabry-Pérot interferometer, integrating a photoacoustic cell and a fiber microphone within a single fiber microcavity. Synergistic enhancement from the low-resonant-frequency, high-quality-factor SRC acoustic structure and MVE-amplified photoacoustic phase demodulation, combined with mode phase difference demodulation for signal-to-noise ratio optimization, significantly improves the performance of conventional fiber microcavity sensors. With an ultra-short optical path length of only 976 μm, our sensor achieves a noise equivalent concentration limit of 567 parts per trillion (ppt) for acetylene, along with a fast response time, excellent long-term stability, and an 8-order-of-magnitude ultra-wide dynamic range, marking the first demonstration of ppt-level acetylene detection in a micron-scale fiber microcavity. This work provides a universal integration strategy for miniaturized ultra-sensitive fiber gas sensors. Physical sciences/Optics and photonics/Other photonics/Photoacoustics Physical sciences/Optics and photonics/Optical techniques/Optical spectroscopy/Near-infrared spectroscopy mode Vernier photoacoustic spectroscopy mode Vernier effect Bragg hollow-core fiber square-ring cantilever mode phase difference Full Text Additional Declarations There is no conflict of interest Supplementary Files SupportingInformation4.17.pdf Supplementary information for Mode Vernier photoacoustic spectroscopy gas sensing using 3D-microprinted on hollow-core fiber tip SupportingInformation.pdf Supplementary information for Mode Vernier photoacoustic spectroscopy gas sensing using 3D-microprinted on hollow-core fiber tip Cite Share Download PDF Status: Under Review Version 1 posted Reviewer # 4 agreed at journal 10 May, 2026 Reviewer # 3 agreed at journal 08 May, 2026 Reviewer # 2 agreed at journal 07 May, 2026 Review # 1 received at journal 06 May, 2026 Reviewer # 1 agreed at journal 30 Apr, 2026 Reviewers invited by journal 23 Apr, 2026 Submission checks completed at journal 23 Apr, 2026 First submitted to journal 21 Apr, 2026 Unknown event 19 Apr, 2026 Editor assigned by journal 17 Apr, 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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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-9451197","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":628196140,"identity":"b5a48a2b-8714-42f4-a009-11bb7569711c","order_by":0,"name":"Wenjun 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However, existing photoacoustic spectroscopy (PAS) technologies face an inherent trade-off between device size and detection sensitivity. Here, we propose mode Vernier photoacoustic spectroscopy (MV-PAS) to break this bottleneck, based on a dual-mode anti-resonant Bragg hollow-core fiber (BHCF) integrated with a two-photon polymerized square-ring cantilever (SRC). The device constitutes a mode Vernier effect (MVE)-enhanced Fabry-Pérot interferometer, integrating a photoacoustic cell and a fiber microphone within a single fiber microcavity. Synergistic enhancement from the low-resonant-frequency, high-quality-factor SRC acoustic structure and MVE-amplified photoacoustic phase demodulation, combined with mode phase difference demodulation for signal-to-noise ratio optimization, significantly improves the performance of conventional fiber microcavity sensors. 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