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The research aimed to study the kinetics of 400 nm blue emission during ultraviolet insolation on germanoslicate optical fiber, hydrogenated, and non-hydrogenataed. The hydrogenation of the fibers was carried out at room temperature under 150 atm for 4 weeks. The focused frequency doubled Argon laser ultraviolet beams were directed to the core of the unsheathed fiber. The light beams emerging from the end of the fiber were directed towards a detector. Kinetics the creation of defects in the hydrogenated fiber followed the power law for low-fluency insolation. At high fluency, the formation of defects followed the principle of two photosensitization or serial steps. [ABSTRACT FROM AUTHOR]

The aim of the research was to examine the formation and destruction of the hydroxyl in optical fibers by comparing the ambient atmosphere, air, and nitrogen during thermal treatment from room temperature up to 1100 °C. It has been shown that during the heat treatment, molecular hydrogen dissolved in the fiber plays no role in the formation of OH while under UV irradiation the formation is dependent on the presence of dissolved hydrogen. The heat treatment preferentially leads to the formation of Si-OH, while during irradiation it assists the formation of both Ge-OH and Si-OH. [ABSTRACT FROM AUTHOR]

The radiation behavior of a commercially available Er-doped fiber is evaluated under varying gamma dose rates with in-situ spectral loss measurements. Complementary post-irradiation photoluminescence measurements allow us to better under- stand the radiation effects. Our results suggest that the microscopic enviromnent of the Er3+ ions is not much affected by the gamma irradiation, unlike the host matrix. We discuss the impact for potential applications of these commercially available fibers in radiation environments. [ABSTRACT FROM AUTHOR]

We report experimental results on the luminescence spectroscopy of hydrogen-loaded-germanosilicate optical fibres annealed in air at various temperatures, up to 500 C, excited at 488 nm. Two kinds of Ge-H defect are identified by their emission bands at 650 or 740 nm. Precursors of the former are drawing-induced GeE defects, whereas the latter are due to the reaction of H2 molecules at the Ge-O-Si site. Another band, centred at 390 nm, is also observed in high-temperature-heated fibres and is proposed to be due to germanium-lone-pair-centre luminescence. [ABSTRACT FROM AUTHOR]

We report on the space-selective precipitation of silver nanoparticles in silica-based and silver-exchanged soda-lime glasses by simultaneous continuous wave ultraviolet exposure and heat treatment. In silica-based glasses, we explain that simultaneous treatments lead to much higher silver nanoparticles concentration than similar treatments performed into two separated steps by minimizing the detrimental influence of oxidation on the nanoparticles’ growth. In the case of silver-exchanged soda-lime glasses, nanoparticles are observed with both small and larger diameters of about 1 and 7 nm, whose concentrations depend both on the laser power density and on the heating temperature. [ABSTRACT FROM AUTHOR]

Abstract: We report on fabrication of Er3+-activated LaF3 nanocrystals in transparent glasses using an original technique, which combines both heat treatment, below glass crystallization temperature, and ultraviolet laser irradiation at 244nm. The main advantage of this method is to control the spatial localization of the nanoparticles in the glass sample, whereas annealing solely at the crystallization temperature leads to a fully crystallized glass sample. Thermal differential analysis was used to determine the crystallization temperature of the sample. The photoluminescence spectra behaviour of Er3+ ions, collected from the UV-irradiated and unirradiated regions, allowed us to follow and to distinguish the structural changes in the glass network under heat treatment and ultraviolet exposure. [Copyright &y& Elsevier]