Suchergebnisse

H. Klym thanks to the Ministry of Education and Science of Ukraine for support and Dr. P. Demchenko for the assistance in XRD experiments. ; Crystallization transformation in the 80GeSe2-20Ga2Se3 chalcogenide glasses caused by annealing at 380 °C during different duration (25, 50, 80 and 100 hours) are studied using X-ray diffraction and atomic force microscopy methods. It is established that GeGa4Se phase of low- and high-temperature modification, Ga2Se3 phase (α- and γ-modification) and GeSe2 phases are crystallized during this process. It is shown that annealing duration over 50 h does not lead to further internal structural crystallization, while annealing for 80 h result in processes of surface crystallization. ; Ministry of Education and Science of Ukraine; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

We demonstrate third-harmonic generation (THG) in a dispersion-engineered slow-light photonic crystal waveguide fabricated in AMTIR-1 chalcogenide glass. Owing to the relatively low loss and low dispersion in the slow-light (c/30) regime, combined with the high nonlinear figure of merit of the material (∼2), we obtain a relatively large conversion efficiency (1.4×10(-8)/W(2)), which is 30× higher than in comparable silicon waveguides, and observe a uniform visible light pattern along the waveguide. These results widen the number of applications underpinned by THG in slow-light platforms, such as the direct observation of the spatial evolution of the propagating mode. ; This work was supported by the Centre of Excellence and Federation Fellowship programs of the Australian Research Council, as well as the School of Physics and the University of Sydney. We also acknowledge the European Union and the UK Engineering and Physical Sciences Research Council through the funding of the Slow Photon Light Activated Switch (SPLASH) project and the Silicon Photonics project.

We demonstrate third-harmonic generation (THG) in a dispersion-engineered slow-light photonic crystal waveguide fabricated in AMTIR-1 chalcogenide glass. Owing to the relatively low loss and low dispersion in the slow-light (c/30) regime, combined with the high nonlinear figure of merit of the material (∼2), we obtain a relatively large conversion efficiency (1.4×10(-8)/W(2)), which is 30× higher than in comparable silicon waveguides, and observe a uniform visible light pattern along the waveguide. These results widen the number of applications underpinned by THG in slow-light platforms, such as the direct observation of the spatial evolution of the propagating mode. ; This work was supported by the Centre of Excellence and Federation Fellowship programs of the Australian Research Council, as well as the School of Physics and the University of Sydney. We also acknowledge the European Union and the UK Engineering and Physical Sciences Research Council through the funding of the Slow Photon Light Activated Switch (SPLASH) project and the Silicon Photonics project.

International audience ; RATIONALE: Rare earth-doped sulphide glasses in the Ga-Ge-Sb-S system present radiative emissions from the visible to the middle infrared range (mid-IR) range, which are of interest for a variety of applications including (bio)-chemical optical sensing, light detection, and military counter-measures. The aim of this work was to reveal structural motifs present during the fabrication of thin films by plasma deposition techniques as such knowledge is important for the optimization of thin film growth. METHODS: The formation of clusters in plasma plume from different concentrations of erbium-doped Ga5 Ge20 Sb10 S65 glasses (0.05, 0.1, and 0.5 wt. % of erbium) using laser (337 nm) desorption ionization (LDI) was studied by time-of-flight mass spectrometry (TOF MS) in both positive and negative ion mode. The stoichiometry of the Gam Gen Sbo Sp (+/-) clusters was determined via isotopic envelope analysis and computer modelling. RESULTS: Several Gam Gen Sbo Sp (+/-) singly charged clusters were found but, surprisingly, only four species (Sb3 S4 (+/-) , GaSb2 Sp (+/-) (p = 4, 5), Ga3 Sb2 S7 (+/-) ) were common to both ion modes. For the first time, species containing rare earths (GaSb2 SEr(+) and GaS6 Er2 (+) ) were identified in the plasma formed from rare earth-doped chalcogenide glasses, directly confirming the importance of gallium presence for rare earth bonding within the glassy matrix. CONCLUSIONS: The local structure of Ga-Ge-Sb-S glasses is at least partly different from the structure of species identified in plasma by mass spectrometry, as deduced from Raman scattering spectroscopy analysis; these glasses are mainly formed by [GeS4/2 ]/[GaS4/2 ] tetrahedra and [SbS3/2 ] pyramids. Extended X-ray absorption fine structure measurements show that Er(3+) ions in Ga-Ge-Sb-S glasses are surrounded by 7 sulphur atoms. Copyright © 2014 John Wiley & Sons, Ltd.

International audience ; RATIONALE: Rare earth-doped sulphide glasses in the Ga-Ge-Sb-S system present radiative emissions from the visible to the middle infrared range (mid-IR) range, which are of interest for a variety of applications including (bio)-chemical optical sensing, light detection, and military counter-measures. The aim of this work was to reveal structural motifs present during the fabrication of thin films by plasma deposition techniques as such knowledge is important for the optimization of thin film growth. METHODS: The formation of clusters in plasma plume from different concentrations of erbium-doped Ga5 Ge20 Sb10 S65 glasses (0.05, 0.1, and 0.5 wt. % of erbium) using laser (337 nm) desorption ionization (LDI) was studied by time-of-flight mass spectrometry (TOF MS) in both positive and negative ion mode. The stoichiometry of the Gam Gen Sbo Sp (+/-) clusters was determined via isotopic envelope analysis and computer modelling. RESULTS: Several Gam Gen Sbo Sp (+/-) singly charged clusters were found but, surprisingly, only four species (Sb3 S4 (+/-) , GaSb2 Sp (+/-) (p = 4, 5), Ga3 Sb2 S7 (+/-) ) were common to both ion modes. For the first time, species containing rare earths (GaSb2 SEr(+) and GaS6 Er2 (+) ) were identified in the plasma formed from rare earth-doped chalcogenide glasses, directly confirming the importance of gallium presence for rare earth bonding within the glassy matrix. CONCLUSIONS: The local structure of Ga-Ge-Sb-S glasses is at least partly different from the structure of species identified in plasma by mass spectrometry, as deduced from Raman scattering spectroscopy analysis; these glasses are mainly formed by [GeS4/2 ]/[GaS4/2 ] tetrahedra and [SbS3/2 ] pyramids. Extended X-ray absorption fine structure measurements show that Er(3+) ions in Ga-Ge-Sb-S glasses are surrounded by 7 sulphur atoms. Copyright © 2014 John Wiley & Sons, Ltd.

Promotor: dr hab. Józef Cybulski, prof. UR - 200 s. ; Szkła chalkogenkowe wykorzystywane są jako materiały dla nowoczesnej fotoniki ze względu na relatywnie niskie koszty wytwarzania. Stosunkowo łatwo osiągalna w procesie produkcji wysoka powtarzalność właściwości szkieł, a także łatwość ich kształtowania oraz wysoka transmisja, zwłaszcza w przypadku szkieł opartych na Se i Te, powodują, że mogą być one stosowane jako urządzenia optyczne (pasywne i aktywne włókna oraz soczewki), a także jako elementy urządzeń półprzewodnikowych. Materiały oparte o chalkogenki znajdują powszechnie zastosowanie zarówno w obszarze cywilnym, np. medycznym, jak i w obszarze militarnym. W trakcie niniejszych badań w celu dalszej optymalizacji właściwości termodynamicznych, mechanicznych, elektrycznych oraz optycznych aktualnych szkieł wytworzono szereg nowych modyfikacji tych materiałów, przeprowadzono także szczegółową charakteryzację uzyskanych materiałów szklanych i szklano-ceramicznych. ; Chalcogenide glasses compose convenient and cost-effective functional media for modern photonics. Due to easy reproducibility and shaping supplemented with an excellent IR transparency, especially in the case of Se- and Te-based glasses they could be employed for many optical (passive and active fibers, lenses, etc) and semiconductive applications. It allows usage of these materials for numerous fields such as civil, military, and medical sectors. Seeking new modifications, a number of amorphous and glass-ceramic systems has been synthesized to optimize and characterize their thermodynamic, mechanical, electrical, and optical properties.

Among infrared atmospheric transmission windows, band II covers the range 3 to 5 µm. This spectral region contains the strongest fingerprint absorption bands of a number of molecules. Thus, mid-infrared lasers are of interest for a variety of applications including laser surgery, environmental and remote sensing. In addition, the band II enables the development of infrared counter-measures for military defense. This work is part of the "mid-infrared light sources development" topic. During this study, we investigated the rare earth doped chalcogenide glass potential as a mid infrared fiber laser emitting light between 3 and 5 µm. This thesis work combines material engineering with amplifier modeling. We focused our attention on the Er3+ or Dy3+-doped Ge20Ga5Sb10S65 and Ge25Ga5Sb10Se60 glass matrices. With both glass compositions, we managed to obtain single core fibers with respective optical losses around 4.5 µm, of 2dB/m for Er-doping and 5 dB/m for Dy-doping. By combining the Ge22Ga3Sb10S65 clad glass with the Er-doped Ge20Ga5Sb10S65 core glass, step index fibers were made with mid-infrared optical losses of 10 dB/m. A spectroscopic study of these doped materials was carried out. Obtained parameters were then used to build a numerical model to simulate the Er-doped Ge20Ga5Sb10S65 fiber amplifier behavior at 4.6 µm when diode pumped at 807 nm. ; La bande II est la région spectrale du moyen infrarouge correspondant à la fenêtre de transmission atmosphérique s'étendant de 3 à 5 µm. Ce domaine spectral présente de nombreux champs d'applications dans le domaine militaire (radars laser, contre-mesures) ainsi que pour l'analyse de gaz (contrôle de la pollution atmosphérique). Ce travail de thèse s'inscrit dans la thématique « élaboration de sources lumineuses pour le moyen infrarouge ». Il présente une approche originale puisqu'il allie élaboration des matériaux, caractérisation spectroscopique et modélisation du milieu amplificateur laser. Cette étude, à l'interface entre la chimie des matériaux vitreux et ...

The chalcogenide Ge2Sb2Te5 (GST) is of interest for use in phase-change memory. Crystallization is the rate-limiting step for memory operation, and can be accelerated by the prior application of a "priming" heating pulse. There is characteristic fading of the priming effect if there is a time interval between the priming pulse and the main heating pulse to achieve crystallization. We apply classical nucleation theory to interpret these effects, based on a fitting of nucleation kinetics (steady-state and transient) over the full temperature range of the supercooled liquid. The input data come from both physical experiments and atomistic simulations. Prior studies of conventional glass-formers such as lithium disilicate preclude any possibility of fading; the present study shows, however, that fading can be expected with the particular thermodynamic parameters relevant for GST and, possibly, other phase-change chalcogenides. We also use the nucleation analysis to highlight the distinction between GST and the other archetypical chalcogenide system (Ag,In)-doped Sb2Te. Classical nucleation theory appears to be applicable to phase-change chalcogenides, and to predict performance consistent with that of actual memory cells. Nucleation modeling may therefore be useful in optimizing materials selection and performance in device applications. ; We acknowledge financial support by the World Premier International Research Center Initiative (WPI), MEXT, Japan, and from the European Research Council under the European Union's Horizon 2020 research and innovation program (grant ERC-2015-AdG-695487: ExtendGlass).

Among infrared atmospheric transmission windows, band II covers the range 3 to 5 µm. This spectral region contains the strongest fingerprint absorption bands of a number of molecules. Thus, mid-infrared lasers are of interest for a variety of applications including laser surgery, environmental and remote sensing. In addition, the band II enables the development of infrared counter-measures for military defense. This work is part of the "mid-infrared light sources development" topic. During this study, we investigated the rare earth doped chalcogenide glass potential as a mid infrared fiber laser emitting light between 3 and 5 µm. This thesis work combines material engineering with amplifier modeling. We focused our attention on the Er3+ or Dy3+-doped Ge20Ga5Sb10S65 and Ge25Ga5Sb10Se60 glass matrices. With both glass compositions, we managed to obtain single core fibers with respective optical losses around 4.5 µm, of 2dB/m for Er-doping and 5 dB/m for Dy-doping. By combining the Ge22Ga3Sb10S65 clad glass with the Er-doped Ge20Ga5Sb10S65 core glass, step index fibers were made with mid-infrared optical losses of 10 dB/m. A spectroscopic study of these doped materials was carried out. Obtained parameters were then used to build a numerical model to simulate the Er-doped Ge20Ga5Sb10S65 fiber amplifier behavior at 4.6 µm when diode pumped at 807 nm. ; La bande II est la région spectrale du moyen infrarouge correspondant à la fenêtre de transmission atmosphérique s'étendant de 3 à 5 µm. Ce domaine spectral présente de nombreux champs d'applications dans le domaine militaire (radars laser, contre-mesures) ainsi que pour l'analyse de gaz (contrôle de la pollution atmosphérique). Ce travail de thèse s'inscrit dans la thématique « élaboration de sources lumineuses pour le moyen infrarouge ». Il présente une approche originale puisqu'il allie élaboration des matériaux, caractérisation spectroscopique et modélisation du milieu amplificateur laser. Cette étude, à l'interface entre la chimie des matériaux vitreux et l'optique, s'intéresse à la faisabilité de sources laser fibrées en verres de chalcogénures dopés terres rares pour l'émission entre 3 et 5 µm. L'objectif de ce travail est d'évaluer le potentiel amplificateur des fibres de verre Ge20Ga5Sb10S65 dopées erbium ou dysprosium entre 4 et 5 µm. Pour ceci, une étude spectroscopique a été effectuée sur le matériau massif. Puis, des fibres optiques à saut d'indice et monoindices ont été réalisées et caractérisées optiquement. Enfin, les paramètres obtenus ont été utilisés pour construire un modèle et simuler le fonctionnement d'un amplificateur laser à fibre Ge20Ga5Sb10S65 dopé Er3+ pompé par diode à 807 nm et opérant à 4,6 µm.

Among infrared atmospheric transmission windows, band II covers the range 3 to 5 µm. This spectral region contains the strongest fingerprint absorption bands of a number of molecules. Thus, mid-infrared lasers are of interest for a variety of applications including laser surgery, environmental and remote sensing. In addition, the band II enables the development of infrared counter-measures for military defense. This work is part of the "mid-infrared light sources development" topic. During this study, we investigated the rare earth doped chalcogenide glass potential as a mid infrared fiber laser emitting light between 3 and 5 µm. This thesis work combines material engineering with amplifier modeling. We focused our attention on the Er3+ or Dy3+-doped Ge20Ga5Sb10S65 and Ge25Ga5Sb10Se60 glass matrices. With both glass compositions, we managed to obtain single core fibers with respective optical losses around 4.5 µm, of 2dB/m for Er-doping and 5 dB/m for Dy-doping. By combining the Ge22Ga3Sb10S65 clad glass with the Er-doped Ge20Ga5Sb10S65 core glass, step index fibers were made with mid-infrared optical losses of 10 dB/m. A spectroscopic study of these doped materials was carried out. Obtained parameters were then used to build a numerical model to simulate the Er-doped Ge20Ga5Sb10S65 fiber amplifier behavior at 4.6 µm when diode pumped at 807 nm. ; La bande II est la région spectrale du moyen infrarouge correspondant à la fenêtre de transmission atmosphérique s'étendant de 3 à 5 µm. Ce domaine spectral présente de nombreux champs d'applications dans le domaine militaire (radars laser, contre-mesures) ainsi que pour l'analyse de gaz (contrôle de la pollution atmosphérique). Ce travail de thèse s'inscrit dans la thématique « élaboration de sources lumineuses pour le moyen infrarouge ». Il présente une approche originale puisqu'il allie élaboration des matériaux, caractérisation spectroscopique et modélisation du milieu amplificateur laser. Cette étude, à l'interface entre la chimie des matériaux vitreux et l'optique, s'intéresse à la faisabilité de sources laser fibrées en verres de chalcogénures dopés terres rares pour l'émission entre 3 et 5 µm. L'objectif de ce travail est d'évaluer le potentiel amplificateur des fibres de verre Ge20Ga5Sb10S65 dopées erbium ou dysprosium entre 4 et 5 µm. Pour ceci, une étude spectroscopique a été effectuée sur le matériau massif. Puis, des fibres optiques à saut d'indice et monoindices ont été réalisées et caractérisées optiquement. Enfin, les paramètres obtenus ont été utilisés pour construire un modèle et simuler le fonctionnement d'un amplificateur laser à fibre Ge20Ga5Sb10S65 dopé Er3+ pompé par diode à 807 nm et opérant à 4,6 µm.

There are two main interests in chalcogenide glasses: their transparency in the infrared and their strong non linear properties. The microstructured optical fibers (MOF) allow single mode signal guiding and/or exacerbate non linear effects. The association of chalcogenide glasses to microstructured geometries permits to obtain single mode and/or non linear fibers in the infrared region. There are many potential applications for MOF. As passive optical component, they can be used to build lasers, for spectrometry of for nulling interferometry. As active optical component, they can be used for signal regeneration, supercontinuum sources, or military applications. The invention of a casting method to make chalcogenide MOF is explained in this thesis. This method permits to obtain the lowest optical losses in chalcogenide MOF. Many MOF were fabricated in As-Se, Te-As-Se glasses. Various fiber geometries were fabricated to cover all the applications. Then, chalcogenide MOF are tested to obtain self phase modulation (SPM) and Raman scattering. Besides, a strongly non linear composition, with good thermal properties to be molded, was determined using a design of experiments. ; L'intérêt des verres de chalcogénures est concentré sur deux points : leur transparence dans l'infrarouge et leurs fortes propriétés non linéaires. Les fibres microstructurées (MOF) permettent de guider un signal monomode et/ou d'exacerber les effets non linéaires. L'association de la géométrie microstructurée aux verres de chalcogénures permet d'obtenir des fibres monomodes et/ou des effets non linéaires importants dans l'infrarouge. Les applications potentielles des MOF sont variées. Si on exploite les propriétés de guidage passif, elles peuvent être utilisées pour la fabrication de lasers fibrés, pour la spectrométrie ou encore pour l'interférométrie. Quand on exploite le guidage actif, les applications concernent la régénération de signal, la génération de sources large bande, la tomographie et la métrologie militaires. Le développement d'une ...