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Title: Real-time gas sensing based on optical feedback in a terahertz quantum-cascade laser
Authors: Hagelschuer, TillWienold, MartinRichter, HeikoSchrottke, LutzGrahn, Holger T.Hübers, Heinz-Wilhelm
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Issue Date: 2017
Published in: Optics Express, Volume 25, Issue 24, Page 30203-30213
Publisher: Washington, DC : Optical Society of America
Abstract: We report on real-time gas sensing with a terahertz quantum-cascade laser (QCL). The method is solely based on the modulation of the external cavity length, exploiting the intermediate optical feedback regime. While the QCL is operated in continuous-wave mode, optical feedback results in a change of the QCL frequency as well as its terminal voltage. The first effect is exploited to tune the lasing frequency across a molecular absorption line. The second effect is used for the detection of the self-mixing signal. This allows for fast measurement times on the order of 10 ms per spectrum and for real-time measurements of gas concentrations with a rate of 100 Hz. This technique is demonstrated with a mixture of D2O and CH3OD in an absorption cell.
Keywords: Semiconductor lasers; quantum cascade; Optical sensing and sensors; Spectroscopy; high-resolution; Spectroscopy; terahertz.
DDC: 620
License: CC BY 4.0 Unported
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Appears in Collections:Ingenieurwissenschaften

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