In this contribution, the first application of the recently developed GaAs/AlGaAs quantum cascade lasers and hollow waveguides in gas sensing spectroscopy is demonstrated. A multimode GaAs/AlGaAs quantum cascade laser tuned to an emission maximum at 10.009 ?m is used to investigate a mid-infrared absorption of ethene at atmospheric pressure. The laser radiation is focused onto the entrance of a 434 mm long, gas-tight terminated hollow waveguide and it is collected after passing it. Well defined mixtures with ten different concentrations of helium and ethene are flushed through the waveguide. The radiation is analyzed using a Fourier-transform infrared spectrometer (FTIR) equipped with a mercurycadmium- telluride detector. The obtained discrete ethene spectrum is compared to a calculated spectrum finding a good agreement. A detection threshold of 250 ppm and a response time in the range of 100 ms have been obtained with the current setup.

Date Published: 1 March 2001
PDF: 8 pages
Proc. SPIE 4204, Fiber Optic Sensor Technology II, (1 March 2001); doi: 10.1117/12.417417

Published in SPIE Proceedings Vol. 4204:
Fiber Optic Sensor Technology II
Brian Culshaw; Michael A. Marcus; Brian Culshaw; James A. Harrington; Michael A. Marcus; Mohammed Saad, Editor(s)