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56. Potential Applications

Author

Rivera, V. A. G., primary, Silva, O. B., additional, Ledemi, Y., additional, Messaddeq, Y., additional, and Marega, E., additional

Published
2014
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68. Atomic level structure of Ge-Sb-S glasses: Chemical short range order and long Sb-S bonds

Author

Pethes, I, Nazabal, Virginie, Ari, J., Kaban, I, Darpentigny, J., Welter, E., Gutowski, O., Bureau, B., Messaddeq, Y., Jovari, P., Pethes, I, Nazabal, Virginie, Ari, J., Kaban, I, Darpentigny, J., Welter, E., Gutowski, O., Bureau, B., Messaddeq, Y., and Jovari, P.

Abstract

The structure of Ge20Sb10S70, Ge23Sb12S65 and Ge26Sb13S61 glasses was investigated by neutron diffraction (ND), X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS) measurements at the Ge and Sb K-edges as well as Raman scattering. For each composition, large scale structural models were obtained by fitting simultaneously diffraction and EXAFS data sets in the framework of the reverse Monte Carlo (RMC) simulation technique. Ge and S atoms have 4 and 2 nearest neighbors, respectively. The structure of these glasses can be described by the chemically ordered network model: Ge-S and Sb-S bonds are always preferred. These two bond types adequately describe the structure of the stoichiometric glass while S-S bonds can also be found in the S-rich composition. Raman scattering data show the presence of Ge-Ge, Ge-Sb and Sb-Sb bonds in the S-deficient glass but only Ge-Sb bonds are needed to fit diffraction and EXAFS datasets. A significant part of the Sb-S pairs has 0.3-0.4 angstrom longer bond distance than the usually accepted covalent bond length (similar to 2.45 angstrom). From this observation it was inferred that a part of Sb atoms have more than 3 S neighbors., Struktura skel Ge20Sb10S70, Ge23Sb12S65 a Ge26Sb13S61 byla zkoumána měřeními neutronové difrakce (ND), rentgenové difrakce (XRD), extended X-ray absorption fine structure (EXAFS) na Ge a Sb K-hranách a Ramanovým rozptylem. Pomocí současně fitovaných dat z difrakce a EXAFS v rámci reverzní Monte Carlo (RMC) simulační techniky byly pro všechna složení získány strukturní modely ve velkém měřítku. Ge a S atomy mají 4 a 2 nejbližší sousedy. Struktura těchto skel může být popsána chemicky uspořádaných modelem sítě: Ge-S a Sb-S vazby jsou vždy preferovány. Tyto dva typy vazeb adekvátně popisují strukturu stechiometrických skel, zatímco vazby S-S mohou být nalezeny u složení bohatého S. Data Ramanova rozptylu ukazují přítomnost vazeb Ge-Ge, Ge-Sb a Sb-Sb ve sklech s deficitem S, ale pouze vazby Ge-Sb jsou nutné pro fitování difrakčních a EXAFS dat. Významná část párů Sb-S má o 0.3-0.4 angstromu delší vazby než obvykle akceptovaná délka kovalentní vazby (ca 2.45 angstromu). Na základě tohoho pozorování bylo vyvozeno, že část atomů Sb má více než 3 sousední atomy S.

Published
2020

78. Demonstration of a stable, tunable random laser

Author

Hlil, A. R., primary, Thomas, J., additional, Boisvert, J-S., additional, Lima, B. C., additional, García-Puente, Y., additional, Maia, L. J. Q., additional, Ledemi, Y., additional, Messaddeq, Y., additional, Gomes, A. S. L., additional, and Kashyap, R., additional

Published
2020
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80. Violet and blue light amplification in Nd3+-doped fluoroindate glasses

Author

Maciel, G.S., S. Menezes, L. de, Araujo, Cid B. de, and Messaddeq, Y.

Subjects
Lasers -- Research, Glass -- Usage, Neodymium -- Usage, Physics
Abstract

Optical gain at 382 and 414 nm from Nd3+-doped fluoroindate glasses after excitation with lasers operating either at 583 or 532 nm was examined. Stimulated emission resulting from a frequency upconversion process induces an increase in the emitted violet and blue light intensity and emission line narrowing. Large optical gain was measured by pump-probe spectroscopy by employing samples with various Nd3+ concentrations.

Published
1999

85. Negative nonlinear absorption in Er3+-doped fluoroindate glass

Author

B., W. Lozano, Araujo, Cid B. de, Acioli, L.H., and Messaddeq, Y.

Subjects
Optical glass -- Research, Photonics -- Research, Erbium -- Usage, Physics
Abstract

An experiment was conducted to observe negative nonlinear absorption on Er3+-doped fluoroindate glass doped with erbium ions at room temperature. Results revealed strong upconverted fluorescence as well as large nonlinear intensity dependence of the optical transmittance. A system of coupled-rate equations were used to describe the dependence of the upconverted fluorescence intensity with the laser power.

Published
1998

86. Optical spectroscopy of Er3+ and Yb3+ co-doped fluoroindate glasses

Author

Riberiro, C.T.M., Zanatta, A.R., Nunes, L.A.O., Messaddeq, Y., and Aegerter, M.A.

Subjects
Semiconductors -- Optical properties, Photoluminescence -- Research, Physics
Abstract

Er3+ and Yb3+ co-doped fluoroindate glasses were examined using optical absorption, Stokes and anti-Stokes photoluminescence. Upconversion processes were observed as a function of photon excitation energy and temperature for compounds that were prepared with a fixed 2 mol % ErF3 concentration and YbF3 contents ranging from 0 to 8 mol %. Two mechanisms for the anti-Stoke photoluminescence were identified and analyzed based on the experimental data.

Published
1998

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