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164 results on '"Klyamkin, S."'

3. Luminescence in germania-silica fibers in 1-2 {\mu}m region

Author

Borshchevskaia, N. A., Katamadze, K. G., Kulik, S. P., Klyamkin, S. N., Chuvikov, S. V., Sysolyatin, A. A., Tsvetkov, S. V., and Fedorov, M. V.

Subjects
Condensed Matter - Materials Science, Physics - Optics
Abstract

We analyze the origins of the luminescence in germania-silica fibers with high germanium concentration (about 30 mol. % GeO2) in the region 1-2 {\mu}m with a laser pump at the wavelength 532 nm. We show that such fibers demonstrate the high level of luminescence which unlikely allows the observation of photon triplets, generated in a third-order spontaneous parametric down-conversion process in such fibers. The only efficient approach to the luminescence reduction is the hydrogen saturation of fiber samples, however, even in this case the level of residual luminescence is still too high for three-photon registration.

Published
2017
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38. Effect of Hydrogenation of C60Fullerenes on the Properties of Their Transformation Products at High Pressures and Temperatures

Author

Chernogorova, O. P., Drozdova, E. I., Lukina, I. N., Sirotinkin, V. P., Khomich, A. A., Klyamkin, S. N., and Ekimov, E. A.

Abstract

Abstract: New superelastic superhard carbon materials are obtained from C60fullerites hydrogenated in the solid state in a hydrogen atmosphere to a content of 0.4 wt % H (formula ~C60H3.5). Raman spectroscopy, light and electron microscopy, dynamic indentation, and tribological tests are used to study composite materials (CM) synthesized from mixtures of powders of Co and 10-wt % fullerites C60or C60H3.5under a pressure of 8 GPa at a temperature of 800°C. Hydrogenation of the initial fullerites increases the degree of amorphization of the structure of the high-pressure graphite-like phase, while its hardness increases by more than 2.5 times, up to ~52 GPa, and the elastic modulus during indentation increases by about 3 times, up to 333 GPa. The hydrogenation of C60fullerites is a promising method for improving the tribotechnical characteristics of the superelastic hard phase formed during the thermobaric treatment of fullerites, as well as CMs reinforced with particles of such a phase: the CM friction coefficient decreases from 0.25 to 0.01 with a significant increase in wear resistance.

Published
2022
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41. Luminescence in germania-silica fibers in 1-2 ��m region

Author

Borshchevskaia, N. A., Katamadze, K. G., Kulik, S. P., Klyamkin, S. N., Chuvikov, S. V., Sysolyatin, A. A., Tsvetkov, S. V., and Fedorov, M. V.

Subjects
Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Optics (physics.optics)
Abstract

We analyze the origins of the luminescence in germania-silica fibers with high germanium concentration (about 30 mol. % GeO2) in the region 1-2 ��m with a laser pump at the wavelength 532 nm. We show that such fibers demonstrate the high level of luminescence which unlikely allows the observation of photon triplets, generated in a third-order spontaneous parametric down-conversion process in such fibers. The only efficient approach to the luminescence reduction is the hydrogen saturation of fiber samples, however, even in this case the level of residual luminescence is still too high for three-photon registration.

Published
2017
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45. Reduction of the radiation-induced absorption in hydrogenated pure silica core fibres irradiated in situ with gamma-rays

Author

Brichard, B., Tomashuk, A. L., Bogaty, V. A., Fernandez, A., Klyamkin, S. N., Girard, S., Francis Berghmans, and Applied Physics and Photonics

Subjects
SELF-TRAPPED HOLES, OPTICAL-FIBERS, PLASMA DIAGNOSTICS, DEFECT STRUCTURE, VITREOUS SILICA, DIOXIDE, CENTERS, ITER, H-2, BANDS
Abstract

We studied the efficiency of a hydrogen-treatment in different pure silica core fibres irradiated by gamma-ray in an attempt to decrease the radiation-induced absorption (RIA). It is observed that the effect of hydrogen already reduces the drawing-induced band commonly observed in low-OH fibres. During irradiation we observe a large increase of the radiation-induced OH growth with a corresponding significant reduction of the radiation-induced absorption at 0.63 mu m. The presence of hydrogen also reduces the transient radiation-induced absorption at 0.7 mu m sometimes observed in low-OH/low-chlorine fibres and believed to pertain to self-trapped holes (STHs). (c) 2007 Elsevier B.V. All rights reserved.

Published
2007

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