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Proceedings Paper

Highly sensitive direction of trace gases using pulsed quantum cascade lasers
Author(s): Geoffrey Duxbury; Erwan L. Normand; Nigel Langford; Michael T. McCulloch; Stephen Walker
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Paper Abstract

We show that by using a high resolution Fourier transform infrared spectrometer we can map the temporal characteristics of a pulsed quantum cascade laser into the wavenumber domain, and hence show that when a square current pulse is applied to a distributed feedback laser a linear sub-microsecond frequency chirp is developed. We describe a mid infrared spectrometer, that is based upon the use of this linear chirp, which can provide a real-time display of the spectral fingerprint of molecular gases. The sensitivity of the spectrometer is based upon the use of long pathlength White or Herriot cells, and the multiplex advantage associated with recording the entire spectral window during each electrical pulse. For a cell with a path length of 9.6 m, dilution measurements made on the ν9 band transistions of 1,1 difluoroethylene indicate a sensitivity of 30 parts per billion.

Paper Details

Date Published: 23 September 2002
PDF: 8 pages
Proc. SPIE 4817, Diode Lasers and Applications in Atmospheric Sensing, (23 September 2002); doi: 10.1117/12.451459
Show Author Affiliations
Geoffrey Duxbury, Univ. of Strathclyde (United Kingdom)
Erwan L. Normand, Univ. of Strathclyde (United Kingdom)
Nigel Langford, Univ. of Strathclyde (United Kingdom)
Michael T. McCulloch, Univ. of Strathclyde (United Kingdom)
Stephen Walker, Univ. of Strathclyde (United Kingdom)

Published in SPIE Proceedings Vol. 4817:
Diode Lasers and Applications in Atmospheric Sensing
Alan Fried, Editor(s)

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