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| Titel |
Multi-species trace gas analysis with dual-wavelength quantum cascade laser |
| VerfasserIn |
Jana Jágerská, Béla Tuzson, Herbert Looser, Pierre Jouy, Andreas Hugi, Markus Mangold, Patrik Soltic, Jérôme Faist, Lukas Emmenegger |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110020
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| Publikation (Nr.) |
 EGU/EGU2015-9982.pdf |
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| Zusammenfassung |
| Simultaneous detection of multiple gas species using mid-IR laser spectroscopy is highly
appealing for a large variety of applications ranging from air quality monitoring, medical
breath analysis to industrial process control. However, state-of-the-art distributed-feedback
(DFB) mid-IR lasers are usually tunable only within a narrow spectral range, which generally
leads to one-laser-one-compound measurement strategy. Thus, multi-species detection
involves several lasers and elaborate beam combining solutions [1]. This makes them
bulky, costly, and highly sensitive to optical alignment, which limits their field
deployment.
In this paper, we explore an alternative measurement concept based on a dual-wavelength
quantum cascade laser (DW-QCL) [2]. Such a laser can emit at two spectrally distinct
wavelengths using a succession of two DFB gratings with different periodicities and a
common waveguide to produce one output beam. The laser design was optimized for NOx
measurements and correspondingly emits single-mode at 5.26 and 6.25 μm. Electrical
separation of the respective laser sections makes it possible to address each wavelength
independently. Thereby, it is possible to detect NO and NO2 species with one laser using the
same optical path, without any beam combining optics, i.e. in a compact and cost-efficient
single-path optical setup.
Operated in a time-division multiplexed mode, the spectrometer reaches detection limits
at 100 s averaging of 0.5 and 1.5 ppb for NO2 and NO, respectively. The performance of the
system was validated against the well-established chemiluminescence detection while
measuring the NOx emissions on an automotive test-bench, as well as monitoring the
pollution at a suburban site.
[1] B. Tuzson, K. Zeyer, M. Steinbacher, J. B. McManus, D. D. Nelson, M. S. Zahniser,
and L. Emmenegger, “Selective measurements of NO, NO2 and NOy in the free troposphere
using quantum cascade laser spectroscopy,” Atmospheric Measurement Techniques 6,
927–936 (2013).
[2] J. Jágerská, P. Jouy, A. Hugi, B. Tuzson, H. Looser, M. Mangold, M. Beck, L.
Emmenegger, and J. Faist, “Dual-wavelength quantum cascade laser for trace gas
spectroscopy,” Applied Physics Letters 105, 161109–161109–4 (2014). |
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