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Time-resolved spectral characteristics of external-cavity quantum cascade lasers and their application to stand-off detection of explosives

Zeitaufgelöste spektrale Charakteristik von Quanten Kaskaden Lasern im externen Resonator mit deren Anwendungen für die Ferndetektion von Explosivstoffen
 
: Hinkov, B.; Fuchs, F.; Yang, Q.K.; Kaster, J.M.; Bronner, W.; Aidam, R.; Köhler, K.; Wagner, J.

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Sigrist, M.W.:
Selected papers presented at the 7th International Conference on Tunable Diode Laser Spectroscopy, TDLS 2009. Special issue : Held in Zermatt, Switzerland during the period 13 - 17 July 2009
Berlin: Springer, 2010 (Applied physics. B, Lasers and optics 100.2010, Nr.2)
pp.253-260
International Conference on Tunable Diode Laser Spectroscopy (TDLS) <7, 2009, Zermatt>
English
Conference Paper, Journal Article
Fraunhofer IAF ()
CBRNE detection; infrared spectroscopy; stand-off detection; remote sensing; infrared laser; quantum cascade laser; external cavity laser; Gefahrstoffdetektion; zeitaufgelöste Spektroskopie; Ferndetektion; Infrarot-Laser; Quanten-Kaskaden-Laser; externer Resonator

Abstract
We present the time-resolved spectral analysis of the settling process in a pulsed external-cavity quantum-cascade laser (EC-QC laser) emitting in the wavelength range around 7.4 mu m. Due to mode competition between the two cavities formed by the laser-chip on one hand and the external-cavity on the other hand, a time-dependent spectral emission on a ns time-scale can be observed. Depending on the spectral characteristic of the external cavity with respect to the chip gain curve time-delays of the external cavity emission of 15-35 ns within the 100 ns drive pulse can be observed. Regarding the application, we discuss the results in the context of using the EC-QC laser system together with a high-performance IR-camera for stand-off detection of surface-contaminations with explosives such as TNT. The detected densities can be as small as 10 mu g/cm(2) corresponding to traces left by a fingerprint.

: http://publica.fraunhofer.de/documents/N-142814.html