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Proceedings Paper

Microcavity light emitters and microbolometer detectors for gas monitoring in the 2-5 µm range
Author(s): Eric Mottin; Philippe Ballet; Francois Levy; L. Mathieu; Jean Louis Ouvrier-Buffet; J. Rothman; Jean Jacques Yon; Emmanuel Hadji; Emmanuel Picard
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Paper Abstract

A sensor based on selective optical absorption allows monitoring of hazardous engine exhaust emissions such as gaseous hydrocarbons and carbon monoxide. The IR components presented here offer the potential to develop a compact, fast and selective sensor reaching the technical and cost requirements for on-board automotive applications. Optical gas monitoring requires light sources above 3 μm since most of the gas species have their fundamental absorption peaks between 3 and 6 μm. We report here on resonant microcavity light sources emitting at room temperature between 3 and 5 μm. The emitter combines a CdxHg1-xTe light emitting heterostructure and two dielectric multilayered mirrors. It is optically pumped by a commercial III-V laser diode. The principle of the resonant microcavity emitter allows tailoring of the emission wavelength and the line width to fit the absorption band of a specific gas, ensuring a very good selectivity between species. Moreover, this kind of emitter allows fast modulation enabling high detectivity and short response time. We report performances of light sources in the range 3 - 5 μm allowing the detection of hydrocarbons and carbon monoxide. Association of emitters peaking at different characteristic wavelengths with a single broad band detector allows designing of an optical sensor for several gas species. Sensitivity and time response issues have been characterized: detection of less than 50 ppm of CH4 on a 15 cm path has been demonstrated on synthetic gas; analysis of exhaust gases from a vehicle has allowed the resolution of a cylinder time. This optical sensor offers the potential of various on-board automotive applications.

Paper Details

Date Published: 7 March 2005
PDF: 11 pages
Proc. SPIE 5739, Light-Emitting Diodes: Research, Manufacturing, and Applications IX, (7 March 2005); doi: 10.1117/12.588584
Show Author Affiliations
Eric Mottin, SLIR, CEA (France)
Philippe Ballet, SLIR, CEA (France)
Francois Levy, SLIR, CEA (France)
L. Mathieu, SLIR, CEA (France)
Jean Louis Ouvrier-Buffet, SLIR, CEA (France)
J. Rothman, SLIR, CEA (France)
Jean Jacques Yon, SLIR, CEA (France)
Emmanuel Hadji, SPMM, CEA (France)
Emmanuel Picard, SPMM, CEA (France)

Published in SPIE Proceedings Vol. 5739:
Light-Emitting Diodes: Research, Manufacturing, and Applications IX
Steve A. Stockman; H. Walter Yao; E. Fred Schubert, Editor(s)

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