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Fe2+-doped ZnSe particles were dispersed in a chalcogenide glass matrix amenable to fiber drawing. Adding an alumina shell prevented ZnSe dissolution and preserved normal Fe2+ optical absorption and emission properties.

Optical composite materials made by powder processing routes can suffer from unwanted absorption loss introduced through powder handling. This can be due to impurities that are introduced during different stages of a powder processing protocol such as mixing, sieving, or grinding. The present work has evaluated the prevalence of impurities imparted to powders used to create an optical composite comprised of an As-S-Se chalcogenide base glass and ZnSe powders. The goal of this study was to identify a suitable powder handling protocol that demonstrates control of the starting particle sizes of the refractive index matched glass matrix and dopant ZnSe to acceptable levels and minimizes adverse impurities that can create loss in a glass-ceramic composite preform and envisioned fiber preforms, and fibers formed from them. Employing a heat treatment step under vacuum prior to re-melting glass powders was shown to reduce the concentration of key impurities, OH-, S-H, and Se-H, by 45.0%, 31.1% and 21.2%, respectively, as compared to re-melted material made from powders without specialized handling.

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...

The growth of atomic layer deposited (ALD) Al2O3 on planar ZnSe substrates is studied using in situ spectroscopic ellipsometry. An untreated ZnSe surface requires an incubation period of 27 cycles of ALD Al2O3 before film growth is observed. Pretreating the surface with an ultraviolet generated ozone lowers the incubation to 17 cycles, whereas a plasma-enhanced ALD Al2O3 process can further lower the incubation period to 13 cycles. The use of ozone or plasma-activated oxygen species on ZnSe is found to create ZnO and SeO2, which are responsible for converting ZnSe from a hydrophobic to a hydrophilic surface. The interfacial layer between Al2O3 and ZnSe is mapped using high-resolution transmission electron microscopy and scanning transmission electron microscopy/energy dispersive spectroscopy. SeO2 is volatile and leaves a zinc-rich interface, which is 4.3 nm thick for the ultraviolet generated ozone pretreated sample and 2.5 nm for the plasma-enhanced ALD process.

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.

High brightness light sources in the mid-infrared are of particular interest for a host of different applications. However, the selection and availability of laser gain media in this spectral region are severely lacking. In this manuscript, we demonstrate broadband optical emission in the 3520-5200 nm region from Fe2+-doped ZnSe microparticles dispersed in a chalcogenide glass matrix which is amenable to fiber drawing. A conformal alumina shell was applied to the Fe:ZnSe particles which prevented ZnSe dissolution and preserved normal Fe2+ optical absorption and emission properties during the composite material manufacturing process. The broadband emission properties of the Fe:ZnSe-doped chalcogenide glass material observed here are promising for the future development of fiber lasers operating at wavelengths > 4 µm.

This study evaluates the impact and stability behavior of a candidate protective shell of Al2O3 which aims to hinder the dissolution of ZnSe in As-S-Se glass systems during the so-called ‘grinding-remelt’ process. Atomic Layer Deposition (ALD) was chosen as the route to conformal shell coating and the role of resulting film attributes on powder and bulk composite properties were assessed to ascertain how ALD film attributes aided stability in the chalcogenide glass melt environment. It is shown that an ozone pre-treatment, performed on the ZnSe powders prior to the ALD, improves particle stability, resulting in a significant decrease of the dissolution behavior of coated powders. This enhanced stability increases with shell thickness and with the use of ozone pretreatment step on the powders. Coating chemistry and structure evaluated via XPS and HR-TEM illustrates the mechanism of dissolution for different ZnSe coated particles at varying loading levels in the glass matrix.

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.