{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T15:58:39Z","timestamp":1791302319540,"version":"4.1.0"},"reference-count":35,"publisher":"American Chemical Society (ACS)","issue":"39","license":[{"start":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T00:00:00Z","timestamp":1789948800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100015063","name":"National Institute of Technology Calicut","doi-asserted-by":"publisher","award":["NITC\/CIEI\/SIP-BUDGET\/2023-2024\/01-52"],"award-info":[{"award-number":["NITC\/CIEI\/SIP-BUDGET\/2023-2024\/01-52"]}],"id":[{"id":"10.13039\/501100015063","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,6]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>A four-mirror resonator-based incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS) is demonstrated for the first time for sensitive trace gas detection. The proposed geometry addresses limitations of conventional linear cavities by enabling enhanced alignment flexibility and multiplexed detection through multiple output ports, allowing selective sensitivity optimization for simultaneous multispecies measurements. The resonator, constructed using four high-reflectivity dielectric mirrors (\u223c99.9% and \u223c99.98% over 400\u2013550 nm), provides a long effective optical path length within a compact footprint, while the transmitted light is detected using a CCD array for high-resolution broadband analysis. The optical stability of the cavity is evaluated theoretically based on cavity length and mirror radius of curvature. Laboratory experiments demonstrate a detection limit of 0.3 Mm1\u2013 at 60 s averaging in the 480\u2013550 nm region. Instrument performance is validated using calibrated concentrations of nitrogen dioxide and iodine. Owing to its flexibility, stability, and capability for selective sensitivity enhancement, the proposed system is well suited for field deployment and identifying wide range of gas detection in space-constrained environments.<\/jats:p>","DOI":"10.1021\/acsomega.6c04683","type":"journal-article","created":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T02:02:05Z","timestamp":1790042525000},"page":"59240-59250","source":"Crossref","is-referenced-by-count":0,"title":["A Four-Mirror Incoherent Broadband Cavity-Enhanced\nAbsorption Spectrometer for Trace Gas Detection"],"prefix":"10.1021","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-6067-6506","authenticated-orcid":true,"given":"Salma","family":"Jose","sequence":"first","affiliation":[{"name":"Department of Physics, National Institute of Technology Calicut , , ,","place":["Calicut, Kerala, India, 673601"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Adithya","family":"Danaj","sequence":"additional","affiliation":[{"name":"Department of Physics, National Institute of Technology Calicut , , ,","place":["Calicut, Kerala, India, 673601"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Keerthana Varada","family":"Anilkumar","sequence":"additional","affiliation":[{"name":"Department of Physics, National Institute of Technology Calicut , , ,","place":["Calicut, Kerala, India, 673601"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4628-3651","authenticated-orcid":true,"given":"Ravi","family":"Varma","sequence":"additional","affiliation":[{"name":"Department of Physics, National Institute of Technology Calicut , , ,","place":["Calicut, Kerala, India, 673601"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,9,21]]},"reference":[{"key":"2026100610482788000_cit1","volume-title":"Atmospheric Chemistry\nand Physics: From Air Pollution to Climate Change","author":"Seinfeld","year":"2016","edition":"3"},{"key":"2026100610482788000_cit2","volume-title":"Air Monitoring by\nSpectroscopic Techniques","author":"Sigrist","year":"1994"},{"key":"2026100610482788000_cit3","volume-title":"Chemistry\nof the Upper and Lower Atmosphere","author":"Finlayson-Pitts","year":"2000"},{"issue":"4","key":"2026100610482788000_cit4","doi-asserted-by":"publisher","first-page":"229","DOI":"10.1007\/s40766-024-00054-z","article-title":"Advances in Cavity-Enhanced Methods\nfor High Precision Molecular Spectroscopy and Test of Fundamental\nPhysics","volume":"47","author":"Gianfrani","year":"2024","journal-title":"Riv. Nuovo Cimento"},{"issue":"4","key":"2026100610482788000_cit5","doi-asserted-by":"publisher","first-page":"581","DOI":"10.1007\/s00340-012-5178-3","article-title":"Understanding the\nSensitivity of Cavity-Enhanced Absorption\nSpectroscopy: Pathlength Enhancement versus Noise Suppression","volume":"109","author":"Ouyang","year":"2012","journal-title":"Appl. Phys. B Laser Opt."},{"issue":"8","key":"2026100610482788000_cit6","doi-asserted-by":"publisher","first-page":"1797","DOI":"10.1039\/D3AN00143A","article-title":"Broadband Cavity Enhanced UV-VIS\nAbsorption Spectroscopy\nfor Picolitre Liquid Samples","volume":"148","author":"Fermor-Worth","year":"2023","journal-title":"Analyst"},{"issue":"6\u20137","key":"2026100610482788000_cit7","doi-asserted-by":"publisher","first-page":"745","DOI":"10.1007\/s00340-002-1026-1","article-title":"Cavity-Enhanced\nAbsorption Spectroscopy with a Rapidly\nSwept Diode Laser","volume":"75","author":"Bakowski","year":"2002","journal-title":"Appl. Phys. B Laser Opt."},{"issue":"3\u20134","key":"2026100610482788000_cit8","doi-asserted-by":"publisher","first-page":"284","DOI":"10.1016\/S0009-2614(03)00263-X","article-title":"Incoherent\nBroad-Band Cavity-Enhanced\nAbsorption Spectroscopy","volume":"371","author":"Fiedler","year":"2003","journal-title":"Chem. Phys. Lett."},{"issue":"11","key":"2026100610482788000_cit9","doi-asserted-by":"publisher","first-page":"3646","DOI":"10.3390\/s18113646","article-title":"Review\nof Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy (IBBCEAS)\nfor Gas Sensing","volume":"18","author":"Zheng","year":"2018","journal-title":"Sensors"},{"key":"2026100610482788000_cit10","doi-asserted-by":"publisher","first-page":"24","DOI":"10.1016\/j.saa.2018.09.023","article-title":"Open Path Incoherent Broadband Cavity-Enhanced\nMeasurements of NO3 Radical and Aerosol Extinction in the North China\nPlain","volume":"208","author":"Suhail","year":"2019","journal-title":"Spectrochim. Acta, Part A Mol. Biomol.\nSpectrosc."},{"key":"2026100610482788000_cit11","doi-asserted-by":"publisher","first-page":"B159","DOI":"10.1364\/AO.48.00B159","article-title":"Long Optical Cavities\nfor Open-Path Monitoring of Atmospheric\nTrace Gases and Aerosol Extinction","volume":"48","author":"Varma","year":"2009","journal-title":"Appl. Opt."},{"issue":"1","key":"2026100610482788000_cit12","doi-asserted-by":"publisher","first-page":"111","DOI":"10.1007\/s41810-021-00128-z","article-title":"Retrieval of Broadband Optical Properties from Ambient Aerosols Measurements\nUsing Inverse Mie Calculations","volume":"6","author":"Saseendran","year":"2022","journal-title":"Aerosol Sci.\nEng."},{"issue":"1","key":"2026100610482788000_cit13","doi-asserted-by":"publisher","first-page":"21","DOI":"10.5194\/amt-3-21-2010","article-title":"Intercomparison of Measurements of\nNO2 Concentrations\nin the Atmosphere Simulation Chamber SAPHIR during the NO3Comp Campaign","volume":"3","author":"Fuchs","year":"2010","journal-title":"Atmos. Meas. Tech."},{"issue":"3","key":"2026100610482788000_cit14","doi-asserted-by":"publisher","first-page":"890","DOI":"10.1021\/es0716913","article-title":"Incoherent\nBroadband Cavity-Enhanced Absorption Spectroscopy in the near-Ultraviolet:\nApplication to HONO and NO2","volume":"42","author":"Gherman","year":"2008","journal-title":"Environ. Sci. Technol."},{"issue":"1","key":"2026100610482788000_cit15","doi-asserted-by":"publisher","first-page":"273","DOI":"10.5194\/amt-13-273-2020","article-title":"Quantification of Nitrous Acid (HONO) and Nitrogen\nDioxide (NO2) in Ambient Air by Broadband Cavity-Enhanced Absorption\nSpectroscopy (IBBCEAS) between 361 and 388 Nm","volume":"13","author":"Jordan","year":"2020","journal-title":"Atmos. Meas. Tech."},{"issue":"2\u20133","key":"2026100610482788000_cit16","doi-asserted-by":"publisher","first-page":"173","DOI":"10.1007\/s00340-002-0980-y","article-title":"Cavity\nRing-down Spectroscopy for\nAtmospheric Trace Gas Detection: Application to the Nitrate Radical\n(NO3)","volume":"75","author":"Brown","year":"2002","journal-title":"Appl. Phys. B Laser Opt."},{"issue":"3","key":"2026100610482788000_cit17","doi-asserted-by":"publisher","DOI":"10.1063\/1.2176058","article-title":"Aircraft Instrument for Simultaneous, in Situ Measurement\nof N O3\nand N2 O5 via Pulsed Cavity Ring-down Spectroscopy","volume":"77","author":"Duba\u0301","year":"2006","journal-title":"Rev. Sci. Instrum."},{"issue":"2","key":"2026100610482788000_cit18","doi-asserted-by":"publisher","first-page":"423","DOI":"10.5194\/amt-9-423-2016","article-title":"A Broadband Cavity Enhanced Absorption\nSpectrometer for Aircraft Measurements of Glyoxal, Methylglyoxal,\nNitrous Acid, Nitrogen Dioxide, and Water Vapor","volume":"9","author":"Min","year":"2016","journal-title":"Atmos. Meas. Tech."},{"issue":"8","key":"2026100610482788000_cit19","doi-asserted-by":"publisher","first-page":"2542","DOI":"10.1039\/D1AN00132A","article-title":"A Dual-Channel Incoherent\nBroadband Cavity-Enhanced Absorption Spectrometer for Sensitive Atmospheric\nNO: Xmeasurements","volume":"146","author":"Pakkattil","year":"2021","journal-title":"Analyst"},{"issue":"14","key":"2026100610482788000_cit20","doi-asserted-by":"publisher","first-page":"3284","DOI":"10.1039\/C8AN00819A","article-title":"Near-Infrared Incoherent Broadband Cavity Enhanced Absorption Spectroscopy\n(NIR-IBBCEAS) for Detection and Quantification of Natural Gas Components","volume":"143","author":"Prakash","year":"2018","journal-title":"Analyst"},{"issue":"17","key":"2026100610482788000_cit21","doi-asserted-by":"publisher","first-page":"3686","DOI":"10.3390\/s19173686","article-title":"Application\nof Near-Infrared Optical Feedback Cavity\nEnhanced Absorption Spectroscopy (OF-CEAS) to the Detection of Ammonia\nin Exhaled Human Breath","volume":"19","author":"Luo","year":"2019","journal-title":"Sensors"},{"issue":"2","key":"2026100610482788000_cit22","doi-asserted-by":"publisher","first-page":"820","DOI":"10.1021\/acssensors.3c02146","article-title":"Near-Infrared\nOff-Axis Cavity-Enhanced Optical Frequency Comb Spectroscopy for CO2\/CO\nDual-Gas Detection Assisted by Machine Learning","volume":"9","author":"Guan","year":"2024","journal-title":"ACS Sens."},{"issue":"9","key":"2026100610482788000_cit23","doi-asserted-by":"publisher","first-page":"247","DOI":"10.1007\/s00340-016-6502-0","article-title":"Optical-Feedback\nCavity-Enhanced Absorption Spectroscopy\nwith an Interband Cascade Laser: Application to SO2 Trace Analysis","volume":"122","author":"Richard","year":"2016","journal-title":"Appl. Phys. B Laser Opt."},{"issue":"30","key":"2026100610482788000_cit24","doi-asserted-by":"publisher","first-page":"4471","DOI":"10.1039\/b802618a","article-title":"Incoherent\nBroad-Band\nCavity-Enhanced Absorption Spectroscopy of the Marine Boundary Layer\nSpecies I2, IO and OIO","volume":"10","author":"Vaughan","year":"2008","journal-title":"Phys. Chem. Chem. Phys."},{"issue":"22","key":"2026100610482788000_cit25","doi-asserted-by":"publisher","first-page":"6643","DOI":"10.5194\/amt-15-6643-2022","article-title":"A Lightweight\nBroadband Cavity-Enhanced Spectrometer for NO2Measurement on Uncrewed\nAerial Vehicles","volume":"15","author":"Womack","year":"2022","journal-title":"Atmos. Meas. Tech."},{"issue":"47","key":"2026100610482788000_cit26","doi-asserted-by":"publisher","first-page":"7098","DOI":"10.1039\/b809591d","article-title":"Incoherent Broadband Cavity-Enhanced\nTotal Internal\nReflection Spectroscopy of Surface-Adsorbed Metallo-Porphyrins","volume":"10","author":"Ruth","year":"2008","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026100610482788000_cit27","doi-asserted-by":"publisher","first-page":"130334","DOI":"10.1016\/j.optcom.2024.130334","article-title":"Design of L-Cavity Using Refractive\nand Reflective Elements","volume":"558","author":"Radhika","year":"2024","journal-title":"Opt. Commun."},{"key":"2026100610482788000_cit28","volume-title":"Matrix Methods in Optical\nInstrument Design","author":"Willem","year":"1964"},{"issue":"3S2","key":"2026100610482788000_cit29","doi-asserted-by":"publisher","first-page":"109","DOI":"10.15625\/0868-3166\/24\/3S2\/5056","article-title":"Design and\nDevelopment of the Folded 4-Mirror Resonators for Diode End-Pumped\nSolid-State Cr:LiSAF Laser","volume":"24","author":"Hao","year":"2016","journal-title":"Comm. Phys."},{"key":"2026100610482788000_cit30","unstructured":"Biswash Tushar, S. N..; Nath, S. D..; Akhtar, J..; Reja, M. I..\n          Modeling and Analysis\nof Z Folded Solid State Laser Cavity with Two Curved Mirrors; International Journal of Microwave and Optical\nTechnology, 2018."},{"issue":"2","key":"2026100610482788000_cit31","doi-asserted-by":"publisher","first-page":"221","DOI":"10.1109\/PROC.1966.4634","article-title":"Statistics\nof Atomic Frequency Standards","volume":"54","author":"Allan","year":"1966","journal-title":"Proc. IEEE"},{"issue":"2","key":"2026100610482788000_cit32","doi-asserted-by":"publisher","first-page":"365","DOI":"10.5194\/essd-5-365-2013","article-title":"The MPI-Mainz\nUV\/VIS Spectral Atlas of Gaseous Molecules of Atmospheric Interest","volume":"5","author":"Keller-Rudek","year":"2013","journal-title":"Earth Syst. Sci. Data"},{"issue":"8","key":"2026100610482788000_cit33","doi-asserted-by":"publisher","first-page":"1059","DOI":"10.1364\/JOSA.56.001059","article-title":"Dispersion of Nitrogen","volume":"56","author":"Peck","year":"1966","journal-title":"J. Opt.\nSoc. Am."},{"issue":"D11","key":"2026100610482788000_cit34","doi-asserted-by":"publisher","first-page":"22955","DOI":"10.1029\/94JD01635","article-title":"Temperature Dependent\nUltraviolet-visible Absorption\nCross Sections of N 2 O and N 2 O 4: Low-temperature Measurements of the Equilibrium Constant for 2NO 2 \u21cc N 2 O 4","volume":"99","author":"Harwood","year":"1994","journal-title":"J. Geophys. Res.:Atmos."},{"issue":"8","key":"2026100610482788000_cit35","doi-asserted-by":"publisher","first-page":"2177","DOI":"10.5194\/acp-6-2177-2006","article-title":"Effects of Column\nDensity on I 2 Spectroscopy and a Determination of I 2 Absorption Cross Section at 500 Nm","volume":"6","author":"Spietz","year":"2006","journal-title":"Atmos. Chem. Phys."}],"container-title":["ACS Omega"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/acsomega.6c04683","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/11\/39\/59240\/68588811\/acsomega.6c04683.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/11\/39\/59240\/68588811\/acsomega.6c04683.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T15:30:30Z","timestamp":1791300630000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/acsodf\/article\/11\/39\/59240\/5434785\/A-Four-Mirror-Incoherent-Broadband-Cavity-Enhanced"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,21]]},"references-count":35,"journal-issue":{"issue":"39","published-online":{"date-parts":[[2026,9,21]]},"published-print":{"date-parts":[[2026,10,6]]}},"URL":"https:\/\/doi.org\/10.1021\/acsomega.6c04683","relation":{},"ISSN":["2470-1343"],"issn-type":[{"value":"2470-1343","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,21]]}}}