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From a dual experimental–theoretical vibrational analysis, we propose a new rationalized structural description of Ge–S–I chalcogenides glasses at the nanoscale. A vibrational multipolar approach based on a simultaneous deconvolution of infrared (IR) and polarized Raman spectra (RS-VV and RS-HV) has been applied on these glasses. According to recent results on the amorphous GeS2 structure by X-Ray and neutron diffraction and to our spectral analyses, we suggest that the local structure of the glass backbone is effectively described by a combination of α-GeS2 nanolayers, edge-sharing GeS4 tetrahedra (ES-Td, ca ∼50%), and corner-sharing GeS4 tetrahedra (CS-Td, ca ∼50%). We have then compared the experimental spectra to the calculated IR and polarized Raman spectra of some selected GexSyIz structural units obtained by density functional theory calculation. The stretching modes of the Ge–S–I occurring in the high frequency spectral range (300–450 cm–1) are essentially those of the GeS2 glass backbone and have...

International audience; Optical composite fibers based on active transition metal (TM)-doped semiconductor crystals are being investigated for use in mid-infrared (mid-IR) fiber laser systems. This study evaluates a candidate glass matrix system assessing its key physical properties and suitability for optical fiber drawing and examines the stability of TM-doped ZnSe crystals during processing. Results indicate that despite excellent refractive index matching between crystal and glass matrix and good fiber draw attributes, the stability of the crystalline dopant within the glass melt is severely impacted by melt conditions. The time and temperature dependence of this stability is mapped by X-ray diffraction (XRD) and second-harmonic generation (SHG) microscopy, illustrating how these tools can be used to track the phase stability and robustness throughout the melting process. Results show that in a range of sulfo-selenide based matrices, dissolution and re-precipitation of Zn-containing crystalline phases is a dominant mechanism.

International audience; The development of novel sensing systems requires breakthroughs in the conception of multifunctional materials. In this sense, while extensive research has been dedicated to the individual tuning of the electrical or optical properties of different materials, the combination of both features would result in a promising field of research that would further extend opportunities for engineering novel function in sensor geometries. In the present work, we employed a highly attractive optical material for mid-infrared (MIR) sensing (chalcogenide glasses, ChG) and focused on the spatial control of its surface electrical potential via a thermoelectrical imprinting process. Different glass compositions based on the system Ge-Sb-S-Na were prepared by varying the sulfur stoichiometry and the sodium content. Each glass was thermally poled using electrodes with specific patterns, and subsequent structural modifications and surface electrical potential were then evaluated via Raman spectroscopy and Kelvin Probe Force Microscopy (KPFM). Raman cartographies show structural modifications attributed to alkali depletion following the patterns of the electrodes used for the imprinting process. Furthermore, KPFM measurements show clearly defined motifs on the electrical potential which are associated to charges implanted into the glass matrix. It was shown that the surface potential can vary in sign within an amplitude range of 10V and exhibit patterning at the micrometer scale. We observed that the efficiency of the surface

International audience; We report for the first time a study on non‐contact thermal poling of soda lime silicate glasses using DC gas discharge. In this work, the formation of a glow discharge is evidenced during the thermal poling treatment (longer than 30 minutes). The hardness and the chemical durability of glasses poled under different conditions (contact or non‐contact) and atmospheres (nitrogen or air) are measured and compared to that of un‐poled reference glass. The results reveal enhanced mechanical and chemical properties for samples poled under nitrogen as compare to air poled or soda lime silicate glass samples. A structural and chemical analysis of surface of the glass using IR‐reflectance measurement and ToF‐SIMS is also presented. The formation of a “silica‐like” layer on the surface of nitrogen poled glasses is observed, which is likely associated with the enhancement of surface properties. On the other hand, the introduction of protons beneath the surface of glasses poled under air leads to the formation of a hydrated alkaline earth silica layer. Based on the observations a mechanism behind the sustainability of the plasma under DC conditions is proposed.

In the present work, series of Ge-S-I glass samples with 5, 10 and 15% of iodine and a concentration of germanium varying between 25 and 35% were prepared and their physical properties such as Tg, density, Visible and infrared light absorption were investigated. From the analysis of the properties close to the stoichiometric composition (GeS 2 ) x I 100-x , we propose an equation of composition that takes into account the effect of iodine as a structure modifier. A great change is observed in the band-gap and Tg values, both of which follow the (GeS 2 ) X —(GeI 4 ) 1-X composition line. We report for the first time a study of the drawing ability of these glasses using a preform-to-fiber drawing technique, to obtain fibers with wide composition range. The results allow us to define a fiber drawing domain inside the glass forming region. We demonstrate that the fiber drawing region is located between two composition lines for which the Mean Coordination Number (MCN) values are 2.4 and 2.55. Attenuation losses measured at 1310 nm for some selected fibers range between 10.9 and 23.0 dB/m.

Several glass compositions of the Ge-As-S ternary system were prepared and their thermal and physical properties were investigated as Tg, Td, theoretical drawing temperature Ts, viscous flow activation energy, density, visible and IR absorption coefficients. The measured values, which are in excellent agreement with the literature, were used to explore the drawing capability of the glass samples. In this work, we report wide range of Ge-As-S optical fiber compositions using the classical preform-to-fiber drawing technique. We show the possibility to obtain optical fibers with sulfur concentration ranging from 35 to 75%, and germanium concentration as high as 35%. In addition, based on the drawing tests we present a fiber drawing domain in the Ge-As-S ternary diagram. The attenuation losses measured at 1310 nm wavelength were between 8.4 and 12.3 dB/m.