Optical, magneto-optical properties and fiber-drawing ability of tellurite glasses in the TeO2-ZnO-BaO ternary system

The presented work is focused on the optical and magneto-optical characterization of TeO2-ZnO-BaO (TZB) tellurite glasses. We investigated the refractive index and extinction coefficient dispersion by spectroscopic ellipsometry from ultraviolet, 0.193 um, up to mid infrared, 25 um spectral region. Studied glasses exhibited large values of linear (n632 = 1.91-2.09) and non-linear refractive index (n2 = 1.20-2.67x10-11 esu), Verdet constant (V632 = 22-33 radT-1m-1) and optical band gap energy (Eg = 3.7-4.1 eV). The materials characterization revealed that BaO substitution by ZnO leads (at constant content of TeO2) to an increase in linear and nonlinear refractive index as well as Verdet constant while the optical band gap energy decreases. Fiber drawing ability of TeO2-ZnO-BaO glassy system has been demonstrated on 60TeO2-20ZnO-20BaO glass with presented mid infrared attenuation coefficient. Specific parameters such as dispersion and single oscillator energy, Abbe number, and first-/ third-order optical susceptibility are enclosed together with the values of magneto-optic anomaly derived from the calculation of measured dispersion of the refractive index

In-situ study of athermal reversible photocrystallization in a chalcogenide glass

The time-resolved Raman measurements reveal a three-stage mechanism of the photostructural changes in Ge25.0Ga9.5Sb0.5S65.0 (containing 0.5 at. % of Er3+) glass under continuous-above-bandgap illumination. These changes are reversible and effectively athermal, in that the local temperature rises to about 60% of the glass-transition temperature and the phase transitions take place in the glass/crystal and not in an equilibrium liquid. In the early stages of illumination, the glassy-network dimensionality changes from a predominantly 3-D to a mixture of 2-D/1-D represented by an increase in the fraction of edge-sharing tetrahedra and the emergence of homonuclear (semi)metallic bonds. This incubation period of the structural rearrangements, weakly thermally activated with an energy of ∼0.16 eV, facilitates a reversible photocrystallization. The photocrystallization rate in the glass is comparable to that achieved by thermal crystallization from supercooled liquid at large supercooling. Almost complete re-amorphization can be achieved in about an hour by reducing the incident laser-power density by a factor of ten. Glass-ceramic composites—with varying glass-to-crystal fraction—can be obtained by ceasing the illumination during re-amorphization. Microstructural imaging reveals photoinduced mass transport and the formation of columnar-porous structures. This shows the potential for a bond-specific engineering of glassy structures for photonic applications with a spatial resolution unachievable by thermal annealing.</jats:p

Down-conversion in Tm3 +/Yb3 + doped glasses for multicrystalline silicon photo-voltaic module efficiency enhancement

Efficiency enhancement of a multicrystalline silicon solar cell using down-conversion of Tm3+ and Yb3+ doped silicate glasses was investigated. Na2O-CaO-SiO2 glasses doped with Tm3+ or Tm3+ and Yb3+ were prepared. Distributed Bragg Reflector (DBR) coatings were sputtered on the glass surface to control the transmission and reflection of the desired portion of the solar spectrum. These were placed on a multicrystalline silicon solar cell in combination with a solar spectrum simulator. The efficiency of solar cell with Tm3+ or Tm3+ and Yb3+ doped glasses increased compared to as-prepared glass without rare-earth addition. The efficiency of solar cell with rare earth doped glasses was re-measured three times with same samples, and the real efficiency enhancement can be proved. The potentials, limitations and future perspectives of rare-earth doped glasses with DBR structure on the efficiencies of PV modules were discussed. (C) 2013 Elsevier B.V. All rights reserved.X1143sciescopu

Down-conversion in Tm3 +/Yb3 + doped glasses for multicrystalline silicon photo-voltaic module efficiency enhancement

Efficiency enhancement of a multicrystalline silicon solar cell using down-conversion of Tm3+ and Yb3+ doped silicate glasses was investigated. Na2O-CaO-SiO2 glasses doped with Tm3+ or Tm3+ and Yb3+ were prepared. Distributed Bragg Reflector (DBR) coatings were sputtered on the glass surface to control the transmission and reflection of the desired portion of the solar spectrum. These were placed on a multicrystalline silicon solar cell in combination with a solar spectrum simulator. The efficiency of solar cell with Tm3+ or Tm3+ and Yb3+ doped glasses increased compared to as-prepared glass without rare-earth addition. The efficiency of solar cell with rare earth doped glasses was re-measured three times with same samples, and the real efficiency enhancement can be proved. The potentials, limitations and future perspectives of rare-earth doped glasses with DBR structure on the efficiencies of PV modules were discussed. (C) 2013 Elsevier B.V. All rights reserved.

Glass formation and properties of the TeO2-ZnO-BaO tellurite optical glasses

International audienceWe report the thorough study on glass forming ability and properties of the TeO2-ZnO-BaO (TZB) optical glasses prepared by the melt-quenching method at 900 °C. The attention has been paid to investigation of thermal, structural, and optical properties of glasses with content of TeO2 from 52.5 up to 90%. The introduction of ZnO and/or BaO into TeO2-based glass results in increase of the glass transition temperature Tg from 319 to 369 °C and decrease of the refractive index and density of prepared glasses. The structure of studied TZB glasses was investigated by Raman scattering. Since the TZB glasses exhibit good thermal stability, wide spectral region of transparency from ultraviolet (UV), λ ≈ 0.35 μm, up to mid-infrared (MIR), λ ≈ 6 μm, wavelengths with high values of refractive index (n1550 ≈ 1.87–2.04), they may be utilized as optical materials, which can be designed on the results presented in this paper

Green, red and near-infrared photon up-conversion in Ga–Ge–Sb–S:Er3+ amorphous chalcogenides

We report on compositional tuning in Et3+ ions doped Ga-Ge-Sb-S glassy system allowing for effective H-2(11/2) -> I-4(15/2) (530 nm), S-4(3/2) -> I-4(15/2) (550 nm), F-4(9/2) -> I-4(15/2) (660 mm), I-4(9/2) -> I-4(15/2) ( 810 nm), I-4(11/2) -> I-4(15/2) (990 nm) intra-4f electronic transition emissions of Er3+ ions under 808 nm, 980 nm or 1550 nm laser pumping. We changed the composition of well-known Ge20Ga5Sb10S65 glass to Ge25Ga10-xSbxS65, where x=0.5 at%, 2.5 at% or 5.0 at% and doped it with 0.5 at% of Er3+ ions. The short-wavelength absorption edge of the studied glassy hosts is blue-shifted by substitution of Sb with Ga to similar to 500 nm making the green emission at 530 nm and 550 nm and even 495 nm (F-4(7/2)-> I-4(15/2)) observable, while the glass stability was kept high characterized with the difference of T-c-T-g>100 K and mean coordination numbers 2.67-2.71. Up-conversion emission decay times of all anti-Stokes emissions were in the range of 0.2-2.1 ms. The influence of Ga substitution with Sb on the structure and the optical properties was investigated. The spectroscopic parameters for Er3+ ions with local environment change were analyzed based on Judd-Ofelt theory. (C) 2013 Elsevier B.V. All rights reserved.X111010sciescopu