Capteurs optiques en fibres de verre de chalcogénure dopées terres rares appliqués à la surveillance du stockage géologique de CO2

The increase of CO2 emissions causes global warming harmful to ecological balances in earth. In this context, CO2 storage in geological formations is an interesting way to limit the consequences of these emissions. However, this solution requires continuous monitoring to detect possible leaks at storage area. The presented work involves the development of an optical fiber sensor based on chalcogenide glasses for the CO2 gas detection operating in the infrared. This detection is based on a luminescent phenomenon, acts as a remote source and partly absorbed in the presence of CO2. The development of these fiber optic asked important work in materials science and spectroscopic characterization. A prototype was manufactured and successfully used in the field during measurement campaigns in situ.L’augmentation des émissions de CO2 entraîne un réchauffement de la planète préjudiciable aux équilibres écologiques terrestres. Dans ce contexte, le stockage de CO2 dans des formations géologiques terrestres et sous-marines se pose comme un moyen intéressant de limiter les conséquences de ces émissions. Cependant cette solution nécessite une surveillance continue afin de détecter d’éventuelles fuites au niveau d’une zone de stockage. Les travaux de thèse présentés concernent le développement d’un capteur optique en fibre de chalcogénures pour la détection de CO2 gazeux fonctionnant dans le moyen infrarouge. Cette détection est basée sur un phénomène de luminescence, jouant le rôle de source déportée et partiellement absorbée en présence de CO2. Le développement de ces fibres optiques a demandé un important travail en sciences des matériaux et en caractérisation spectroscopique. Un prototype a été fabriqué et utilisé avec succès sur le terrain lors de campagnes de mesure menées in-situ

Local motifs in GeS2_2-Ga2_2S3_3 glasses

The structure of (GeS$_2$)$_{0.75}$(Ga$_2$S$_3$)$_{0.25}$ and (GeS$_2$)$_{0.83}$(Ga$_2$S$_3$)$_{0.17}$ glasses was investigated by Raman scattering, high energy X-ray diffraction and extended X-ray absorption fine structure (EXAFS) measurements at the Ga and Ge K-edges. The reverse Monte Carlo simulation technique (RMC) was used to obtain structural models compatible with diffraction and EXAFS datasets. It was found that the coordination number of Ga is close to four. While Ge atoms have only S neighbors, Ga binds to S as well as to Ga atoms showing a violation of chemical ordering in GeS$_2$-Ga$_2$S$_3$ glasses. Analysis of the corner- and edge-sharing between [GeS$_{4/2}$] units revealed that about 30% of germanium atoms participate in the edge-shared tetrahedra.Comment: 23 pages, 7 figures, accepted for publication in Journal of Alloys and Compound

Réalisation de structures optiques verticales en verres de chalcogénure pour des applications dans le proche et moyen infrarouge

National audienceDes structures verticales que sont des miroirs de Bragg et des microcavités ont été élaborées en verres de chalcogénure. Une étude préliminaire a permis d'étudier l'indice de réfraction des différentes couches de verres massifs de chalcogénure ainsi que la vitesse de formation de ces couches déposées par PLD. L'objectif de ce travail est de réaliser des microcavités actives en dopant la couche séparatrice par des ions Erbium émettant à 1,53 et à 4,65 µm

Rare earth doped chalcogenide glasses optical fiber sensors applied for monitoring and storage of CO2

L'augmentation des émissions de CO2 entraîne un réchauffement de la planète préjudiciable aux équilibres écologiques terrestres. Dans ce contexte, le stockage de CO2 dans des formations géologiques terrestres et sous-marines se pose comme un moyen intéressant de limiter les conséquences de ces émissions. Cependant cette solution nécessite une surveillance continue afin de détecter d'éventuelles fuites au niveau d'une zone de stockage. Les travaux de thèse présentés concernent le développement d'un capteur optique en fibre de chalcogénures pour la détection de CO2 gazeux fonctionnant dans le moyen infrarouge. Cette détection est basée sur un phénomène de luminescence, jouant le rôle de source déportée et partiellement absorbée en présence de CO2. Le développement de ces fibres optiques a demandé un important travail en sciences des matériaux et en caractérisation spectroscopique. Un prototype a été fabriqué et utilisé avec succès sur le terrain lors de campagnes de mesure menées in-situ.The increase of CO2 emissions causes global warming harmful to ecological balances in earth. In this context, CO2 storage in geological formations is an interesting way to limit the consequences of these emissions. However, this solution requires continuous monitoring to detect possible leaks at storage area. The presented work involves the development of an optical fiber sensor based on chalcogenide glasses for the CO2 gas detection operating in the infrared. This detection is based on a luminescent phenomenon, acts as a remote source and partly absorbed in the presence of CO2. The development of these fiber optic asked important work in materials science and spectroscopic characterization. A prototype was manufactured and successfully used in the field during measurement campaigns in situ

Fabrication of high optical quality Ge-As-Se glasses for the development of low-loss microstructured optical fibers

International audienceIn the last twenty years the field of chalcogenide glasses has seen increasing interest, due to their broad transparency window in the mid-IR. Furthermore, chalcogenides are showing one of the highest nonlinear refractive indices among glasses. Due to these reasons, the development of chalcogenide microstructured optical fibers with low optical losses can allow for new breakthroughs in various research fields, e.g. new mid-IR laser sources, mid-IR spectroscopy, sensing and applications based on nonlinear effects, like supercontinuum generation. In this framework, chalcogenide glasses with the lowest possible amount of impurities are needed to minimize absorption losses. This study is focused on the attempt of eliminating the pollutants usually giving rise to absorption peaks inside the transparency windows oxygen, hydrogen, carbon and water. Samples were prepared using a double distillation method getters that can react with the impurities during the synthesis were added to the initial charge, and the reaction byproducts were eliminated by a two-steps distillation process. Ge(10)As(22)Se(68 )was chosen as the system to study because of its nonlinear, optical and thermomechanical properties. Different combinations of chlorides (for the elimination of hydrogen and carbon) and metals (for the elimination of oxygen) were used, and the attenuation spectra of the resulting glasses were compared. The chosen chlorides are TeCl4, SeCl4, SbCl3, GaCl3; the metals are Mg, Al, Zr, Ni. A holey fiber has been realized by casting method using the best sample, showing that the method is suitable for this composition and that the attenuation before and after the casting are comparable

Purification of Ge-As-Se ternary glasses for the development of high quality microstructured optical fibers

International audienceThe production of chalcogenide microstructured optical fibers with low optical losses, due to the broad transparency window of these glasses in the mid-IR, can allow for new breakthroughs in various research fields, e.g. new mid-IR laser sources and mid-IR spectroscopy. In this framework, high purity chalcogenide glasses are needed in order to minimize absorption losses. In this study, Ge10As22Se68 samples were prepared using a double distillation method, using different combinations of chlorides and metals as getters for the physico-chemical elimination of carbon, oxygen and hydrogen impurities. Comparing the attenuation spectra of the different samples, the choice of the getters seems to be indeed a significant factor in the quality of the glass. A holey fiber has been realized by casting method using the best sample, showing that the method is suitable for this composition and that the attenuation before and after the casting are comparable

From Selenium- to Tellurium-Based Glass Optical Fibers for Infrared Spectroscopies

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Rare-earth-doped selenide ridge waveguides and microdisks on pedestal for integrated mid-infrared light sources

International audienc

IR emitting Dy3+ doped chalcogenide fibers for in situ CO2 monitoring in high pressure microsystems

This paper reports the carbon dioxide detection in silicon-Pyrex high pressure microfluidic devices mimicking geological conditions encountered in deep saline aquifers using an in situ infrared optical sensor. The middle infrared source inserted inside the microchannel is based on infrared emission from Dy3+ sulfide glass fibers. The broad emission of the Dy3+ doping in infrared fibers is used to directly probe the CO2 thanks to the perfect overlap between the rare earth emission centered at 4.4 μm and the CO2 absorption band located at 4.3 μm. CO2 and water were clearly distinguished when using segmented flow on chip at pressures ranging from 4.5 to 6 MPa. These results demonstrate the feasibility of the infrared optical detection of other gases displaying absorption bands in the middle infrared domain for further developments of gas sensors, which can find applications in geological media monitoring and microfluidics.Micro-laboratoires géologiques sur puce pour l'étude des processus clés du transport réactif multiphasique appliqués au stockage géologique du CO2

Fiber evanescent wave spectroscopy based on IR fluorescent chalcogenide fibers

International audienceChalcogenide glasses, owing to their transparency in the infrared window and the appropriate solubility of rare earth, allows the generation of middle infrared (mid-IR) radiation from a near infrared or visible pumping source. These emitted mid-IR broad bands can probe the vibrational modes of several molecules, e.g. C-H, CO or C-Cl. Relying on this principle, a mid-IR optical sensor using the mid-IR fluorescence of Pr3+: Ga-Ge-Sb-S fibers has been developed. The detection principle is based on Fiber Evanescent Wave Spectroscopy (FEWS). The spectroscopic characterization of praseodymium ions (Pr3+) was performed in the near and mid-IR and is discussed on the basis of comparison with Judd-Ofelt calculations. The broad emission spectrum of the Pr3+: Ga-Ge-Sb-S fiber from 4 to 5 μm could enable the monitoring of multiple pollutants. In this study, chloroform detection is carried out via a novel technique derived from FEWS. In this way, an infrared sensor was developed, composed of a pumping source in near-IR, a mid-IR detector and a tapered Pr3+: chalcogenide fiber to enhance the detection sensitivity. These results demonstrate for the first time the feasibility of detecting molecules by FEWS using the mid-IR fluorescence emitted by rare earth ions doping chalcogenide fibers. This method is an effective alternative to the classical FEWS system, as RE doped chalcogenide fibers have the advantage of being a compact mid-IR sourc