Authors: S Welzel J Röpcke
Publish Date: 2010/06/19
Volume: 102, Issue: 2, Pages: 303-311
Abstract
Quantum cascade lasers QCLs have attracted considerable interest as an alternative tuneable narrow bandwidth light source in the midinfrared spectral range for chemical sensing Pulsed QCL spectrometers are often used with short laser pulses and a bias current ramp similar to diode laser spectroscopy Artefacts in the recorded spectra such as disturbed line shapes or underestimated absorption coefficients have been reported A detailed timeresolved highbandwidth analysis of individual pulses during a laser sweep has been performed Quantitative results for CH4 absorption features around 1347 cm−1 742 μm fell short of the expected values for reasonable operating conditions of the QCL The origin of the artefacts using short pulses was identified to be partly of the same nature as in the case of long laser pulses A complex combination with the tuning principle was found leading to an apparently increased instrumental broadening effective line width and underestimated concentrations at lowpressure conditionsThis article is published under an open access license Please check the Copyright Information section for details of this license and what reuse is permitted If your intended use exceeds what is permitted by the license or if you are unable to locate the licence and reuse information please contact the Rights and Permissions team
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