296 research outputs found
Non-toxic sulfide glasses and thin films for optical applications [In, Special Issue Innovative Ceramics]
No full textThis article reviews the fabrication and properties of sulfide glasses and thin films consisting of non-toxic elements: alkaline-earth, rare-earth, germanium and gallium sulfides for optical applications. Refractive indexes, transmission and the fluorescence property of rare-earth ions in sulfide glasses are presented. Factors affecting rare-earth solubility in sulfide glasses are summarized. Thermally-stable BaS-Ga2S3-GeS2 glasses for optical fibers and Nd3+-doped transparent Ga-La-S-O glass-ceramics are described as new optical materials. Sm-doped SrS-Ga2S3 non-crystalline and nano-crystalline metallic SmS films were irradiated by focused femtosecond laser pulses and new photoinduced phenomena are introduced
Effect of poling conditions on second harmonic generation in fused silica
No full textA systematic study of the effects of poling time and applied voltage on second harmonic generation (SHG) in thermally poled silica glass reveals that the SH signal is proportional to the square of the applied voltage, and that the speed of the poling process is inversely proportional to the applied voltage. Prior treatment of the samples is found to affect the poling process, and the optimum poling conditions are observed to depend on the poling atmosphere. The mechanism of thermal poling is discussed in the light of these new results
Glass fibre poling and applications
No full textRecent developments in the application of poled optical fibers to second harmonic generation and electrooptic light modulation are reviewed
Mechanism of glass poling: what happens in the depletion region?
No full textRecently permanent second-order nonlinearities (SON) as high as 1pm/V (~0.2 of the value χ(2) in LiNbO3) have been observed in certain grades of thermally poled commercial fused silica. This result has excited considerable interest because it offers the possibility of parametric frequency converters and linear electrooptic modulators monolithically integrated into optical fibres or planar glass waveguides. A better understanding of the mechanism of glass poling, which is still not fully understood, may help improve the value of SON in poled glass, perhaps to values competitive with the best ferroelectric crystals.& more..
Refractive index dispersion of gallium lanthanum sulfide and oxysulfide glasses
No full textGallium lanthanum sulfide-based glasses are attractive for new laser and nonlinear optical applications at near Infrared region. Refractive indexes were measured for Ga2As3-La2S3 and Ga2S3-La2O3 glasses in the range of 0.5 and 1.7µm using the minimum deviation method. Data is analysed by Wemple and Didomenico equation. These glasses have relatively large average electronic bandgaps E in comparison with other chalcogenide glasses. Possible origins of these features are discussed
Poled glass optical communication devices
No full textA review of electro-optic and nonlinear optical devices based on poled glass is presented, including recent developments and potential applications
Preparation and properties of La<sub>2</sub>O<sub>3</sub>-Ga<sub>2</sub>S<sub>3</sub> glass-ceramics for IR materials
No full textIR transmitting glass-ceramics were prepared by isothermal treatments of La2O3–Ga2S3 glasses. The glass-ceramics were characterized by crystalline phases, microstructure, Vickers hardness and mid (3–5µm) IR transmittance. The Nd2S3-doped La2O3–Ga2S3 glass-ceramics consisting of a large numbers of (LaO)4Ga1.72S4.58, α-(LaO)GaS2 and α-Ga2S3 crystals with <1µm in size exhibit a high hardness of 5.3 GPa and a mid IR transparency of >60%
Compositional dependence of optical properties of Nd<sup>3+</sup> in gallate glasses
No full textThe Judd-Ofelt parameters, spontaneous emission probabilities from the 4F3/2 level, quantum efficiency, and stimulated emission cross section of the 4F3/2 to 4I11/2 transition for Nd3+ are studied for potassium tantalum and lead bismuth gallate glasses. The results reveal that the tantalum gallate glasses have high Omega2 values being comparable to that of Ge-Ga-S glass. The lead bismuth gallate glasses have high stimulated emission cross sections over 4 pm2 because of their high refractive indexes. The variations of the JO parameters with composition are discussed in terms of glass structure
Thermal properties of Ga<sub>2</sub>S<sub>3</sub>-based glass and their consideration during fiber drawing
No full textThermal properties of gallium-lanthanum sulphide and oxysulphide glasses relevant to fiber applications are evaluated. Time-temperature-transformation diagrams of gallium-lanthanum sulphide and oxysulphide glasses are presented based on the results of X-ray diffraction analysis and microstructural observations. Thermal stability of these glasses for fiber drawing is discussed along with the viscosity data of supercooled liquid samples. Favourable fabrication conditions for gallium lanthanum sulphide glass fibers are proposed to minimize microcrystal formation during heating
Second harmonic generation in thermally-poled inorganic glasses
No full textInorganic glasses with inversion symmetry naturally have not been possessing the second order nonlinearities (SONs). However, permanent SONs with 1 pm/V (~0.2 of the value χ22(2) in LiNbO3 have been observed in commercial fused-quartz glasses. For a typical poling condition, samples with 1 mm thick are heated to 280°C with an applied voltage of 4 kV for 15 min and then cooling till room temperature with the field applied. After this poling procedure, the SON is observed only near the anodic surface. This result leads to the interest of the possibility of parametric frequency converters and linear electrooptic modulators monolithically integrated into optical fibers or planar glass waveguides. A better understanding of the mechanism, which is not fully understood, may help improve the value of SON in poled glasses and discover novel SON inorganic glass materials. We have systematically studied the effects of poling conditions, especially poling dc voltage and time on SHG in thermally-poled fused quartz and discovered that the SH signal is proportional to the square of the applied voltage and that the speed of the poling process increases with the applied voltage. Effects of impurity concentrations such as oxygen deficient centre (ODC), Na, and OH in fused quartz glasses were also studied. A correlation of the SH signal with the ODC concentration, which was controlled by annealing temperatures (900 - 1100°C) in air, was observed. The mechanisms and materials conditions to create permanent SONs in various oxide glasses, e.g., fused quartz, sol-gel derived silica, tellurite glasses, are discussed in the light of these new results
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