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

Moldable multispectral glasses in GeS2–Ga2S3–CsCl system transparent from the visible up to the thermal infrared regions

International audienceThis work is based on the development of glasses with extremely wide optical transmission range for multispectral imaging (visible + thermal imaging for example) with the same optical system. Glass compns. based on the GeS2-​Ga2S3-​CsCl system have been selected in order to obtain glasses transparent from the visible up to the 8-​12 μm region. An increase of CsCl content can greatly improve the visible transmission of the glasses which however will be more sensitive to ambient moisture. Two glasses with different chromatic dispersion, necessary for the design of an optical system, are developed and characterized. Molding tests on aspheric surfaces demonstrate clearly the ability of these two glasses to be molded into complex optics without crystn. and with excellent roughness. In order to test the ability of an anti-​reflective coating to protect these glasses against the atm. aggression, a ZnS coating has been applied to these glasses. An effective protection can be achieved with a ZnS coating of less than 1 μm of thickness. These results allow considering the use of compns. with higher CsCl content if still more transparency in the visible region is desired

Pulsed laser deposited amorphous chalcogenide and alumino-silicate thin films and their multilayered structures for photonic applications

International audienceAmorphous chalcogenide and alumino-silicate thin films were fabricated by the pulsed laser deposition technique. Prepared films were characterized in terms of their morphology, chemical composition, and optical properties. Multilayered thin film stacks for reflectors and vertical microcavities were designed for telecommunication wavelength and the window of atmosphere transparency (band II) at 1.54 μm and 4.65 μm, respectively. Bearing in mind the benefit coming from the opportunity of an efficient wavelength tuning or, conversely, to stabilize the photoinduced effects in chalcogenide films as well as to improve their mechanical properties and/or their chemical durability, several pairs of materials from pure chalcogenide layers to chalcogenide/oxide layers were investigated. Different layer stacks were fabricated in order to check the compatibility between dissimilar materials which can have a strong influence on the interface roughness, adhesion, density, and homogeneity, for instance. Three different reflector designs were formulated and tested including all-chalcogenide layers (As40Se60/Ge25Sb5S70) and mixed chalcogenide-oxide layers (As40Se60/alumino-silicate and Ga10Ge15Te75/alumino-silicate). Prepared multilayers showed good compatibility between different material pairs deposited by laser ablation despite the diversity of chemical compositions. As40Se60/alumino-silicate reflector showed the best parameters; its stop band (R > 97% at 8° off-normal incidence) has a bandwidth of ~ 100 nm and it is centered at 1490 nm. The quality of the different mirrors developed was good enough to try to obtain a microcavity structure for the 1.5 μm telecommunication wavelength made of chalcogenide layers. The microcavity structure consists of Ga5Ge20Sb10S65 (doped with 5000 ppm of Er3 +) spacer surrounded by two 10-layer As40Se60/Ge25Sb5S70 reflectors. Scanning and transmission electron microscopies showed a good periodicity, great adherence and smooth interfaces between the alternating dielectric layers confirming a suitable compatibility between the different materials

ICAR: endoscopic skull‐base surgery

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Ultranarrow bandpass hybrid filter with wide rejection band

International audienc

Index determination of opaque and semitransparent metallic films: application to light absorbers

International audienc

Manufacturing of an absorbing filter controlled with a broadband optical monitoring

International audienc