10 March 2016 Spectroscopic benzene detection using a broadband monolithic DFB-QCL array
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Proceedings Volume 9767, Novel In-Plane Semiconductor Lasers XV; 97671T (2016) https://doi.org/10.1117/12.2213696
Event: SPIE OPTO, 2016, San Francisco, California, United States
Quantitative laser spectroscopic measurements of complex molecules that have a broad absorption spectra require broadly tunable laser sources operating preferably in the mid-infrared molecular fingerprint region. In this paper a novel broadband mid-infrared laser source comprising of an array of single-mode distributed feedback quantum cascade lasers was used to target a broadband absorption feature of benzene (C6H6), a toxic and carcinogenic atmospheric pollutant. The DFB-QCL array is a monolithic semiconductor device with no opto-mechanical components, which eliminates issues with mechanical vibrations. The DFB-QCLs array used in this work provides spectral coverage from 1022.5 cm-1 to 1053.3 cm-1, which is sufficient to access the absorption feature of benzene at 1038 cm-1 (9.64 μm). A sensor prototype based on a 76 m multipass cell (AMAC-76LW, Aerodyne Research) and a dispersive DFB-QCL array beam combiner was developed and tested. The Allan deviation analysis of the retrieved benzene concentration data yields a short-term precision of 100 ppbv/Hz1/2 and a minimum detectable concentration of 12 ppbv for 200 s averaging time. The system was also tested by sampling atmospheric air as well as vapors of different chemical products that contained traces of benzene.
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Rafał Lewicki, Rafał Lewicki, Mark Witinski, Mark Witinski, Biao Li, Biao Li, Gerard Wysocki, Gerard Wysocki, "Spectroscopic benzene detection using a broadband monolithic DFB-QCL array", Proc. SPIE 9767, Novel In-Plane Semiconductor Lasers XV, 97671T (10 March 2016); doi: 10.1117/12.2213696; https://doi.org/10.1117/12.2213696

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