16 February 2005 Resonant microcavity light emitters for onboard exhaust emissions IR sensor
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Proceedings Volume 5663, Photonics in the Automobile; (2005) https://doi.org/10.1117/12.597602
Event: European Workshop on Photonics in the Automobile, 2004, Geneva, Switzerland
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 3μm 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 5μm. 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 3-5μm 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 50ppm of CH4 on a 15cm path has been demonstrated on synthetic gas; analysis of exhaust gases from a vehicle has allowed cylinder to cylinder resolution. This optical sensor offers the potential of various on-board automotive applications.
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Francois Levy, Francois Levy, Emmanuel Picard, Emmanuel Picard, Johan Rothmann, Johan Rothmann, Eric Mottin, Eric Mottin, Emmanuel Hadji, Emmanuel Hadji, Joel Duhr, Joel Duhr, } "Resonant microcavity light emitters for onboard exhaust emissions IR sensor", Proc. SPIE 5663, Photonics in the Automobile, (16 February 2005); doi: 10.1117/12.597602; https://doi.org/10.1117/12.597602
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