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Lasers à cristaux photoniques pour la spectroscopie infrarouge

Souad Moumdji 1 
1 LAAS-PHOTO - Équipe Photonique
LAAS - Laboratoire d'analyse et d'architecture des systèmes
Abstract : Mitigation of atmospheric emissions is an important concern for today's society. This PhD work is in keeping with this pattern by proposing to study and realize laser devices to be integrated in systems for detecting polluting gases. Tunable diode laser absorption spectroscopy is a technique for gas detection which is very sensitive and selective. It makes use of laser diodes operating in the continuous wave regime at room temperature with a single frequency emission and a large tuning range. For fulfilling these requirements, we propose an innovative design where two laser cavities are coupled by a photonic crystal mirror (PC). The mid-infrared range (2 to 5 µm), where numerous gas species have strong absorption lines, is of particular interest for these applications. The antimonide system is the best suited for reaching this wavelength range because it allows to make devices emitting beyond 2 µm.Two designs have been studied, one with PCs placed on both sides of the ridge, the other one with PCs going through the ridge. Modelling has shown that the second design is the most efficient. A major challenge in this work was to develop a complete technological process making use of photolithography steps combined with electronic insulation steps for defining the PCs and opening the insulator layer. A special care has been devoted to perfecting deep etching of the PCs. Subsequent characterizations showed that the devices work in the continuous wave regime at room temperature. Single frequency emission was obtained. Absorption measurements with methane and carbon monoxide have validated the use of these devices in a system for gas detection.
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Submitted on : Thursday, September 25, 2014 - 10:46:56 AM
Last modification on : Wednesday, June 1, 2022 - 4:31:28 AM
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  • HAL Id : tel-01068165, version 1

Citation

Souad Moumdji. Lasers à cristaux photoniques pour la spectroscopie infrarouge. Electronique. Université Montpellier II - Sciences et Techniques du Languedoc, 2011. Français. ⟨tel-01068165⟩

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