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In this paper, we report on fabricating optical fibers with a controlled process of crystallization core during the drawing process. The research and synthesis of the core material of silica-germanium-antimony oxide glass were discussed. We also investigated the optical and luminescence properties were in relation to concentrating Eu 2 O 3 and P 2 O 5. Based on this investigation, we selected the most promising material for optical fiber core. In the next step, we drew optical fibers using a well-known rod-in-tube method. After drawing, we examine the optical fibers for luminescence shape changes. We observed a promising similarity between optical fibers and heat-treated samples with confirmed nanocrystals. Finally, XRD and TEM measurements confirm EuPO 4 nanocrystals at the core of the optical fiber. Highlighting the successful control of crystallization in the one-step method used to draw optical fibers. [ABSTRACT FROM AUTHOR]

In this paper, we performed a comparative spectroscopic analysis of Tm3+-doped glasses based on GeO 2 -BaO-Ga 2 O 3 (GBG) and TiO 2 -GeO 2 -BaO-Ga 2 O 3 (TGBG) to achieve broadband luminescence at 1.8 μm. Glasses were prepared at different doping concentrations (0.05 mol% and 1mol%) in order to investigate the effect of Tm3+ ions as well as host composition (GeO 2 :TiO 2 molar ratios) on near-IR luminescence properties. We report on the hypersensitivity of the transition 3H 6 → 3F 4 of Tm3+ in a series of titanate-germanate glasses, which was shifted to longer wavelengths with increasing TiO 2 concentration. The relative intensity of the main near-IR emission band corresponding to the 3F 4 → 3H 6 (1.8 μm) transition of Tm3+ was 4.8-fold enhanced for glass with molar ratio GeO 2 :TiO 2 = 1:5 compared to GBG glass system. We observed the luminescence quenching phenomena for samples containing more than 0.5 mol% of Tm3+ ions. The calculated spectroscopic parameters, such as measured luminescence lifetime (τ m) and the quantum efficiency (η), were discussed and compared to the different laser glasses. Importantly, luminescence decay curves have been examined using the Inokuti-Hirayama model. Additionally, the correlation between optical properties and local structure in glasses was well evidenced by Raman spectroscopy. The proposed strategy, in combination with various chemical composition of glass host activated by various Tm 2 O 3 concentration, might be beneficial for modern near-infrared photonics. • NIR emission of Tm3+ in BGG glass was examined with TiO 2 and activator content. • The main band due to 3F 4.→ 3H 6 transition of Tm3+ was 4.8-fold enhanced. • The hypersensitive 3H 6.→ 3F 4 transition of Tm3+ was shifted to longer wavelengths. • The luminescence decay curves were examined by the Inokuti-Hirayama model. • Tm3+-doped glasses with GeO 2 :TiO 2 = 1:1, 1:2, 1:3 can be attractive for photonics. [ABSTRACT FROM AUTHOR]

Influence of titanium dioxide concentration on thermal properties of germanate-based glasses has been studied. Germanate glasses varying with TiO2 content were examined using DSC methods. The DSC curves exhibit two exothermic peaks, when GeO2 is substituted by TiO2. Based on DSC measurements, characteristic temperatures were determined. The studies demonstrate that glass transition temperature increases, whereas thermal stability parameters are reduced with increasing TiO2 concentration. The DSC curves were also acquired with different heating rates, and the Kissinger method was used to calculate the activation energy. X-ray diffraction analysis for germanate-based glass with TiO2 indicates that crystallization processes are more complex and several phases are formed during annealing. The absorption and emission spectra of glass samples doped with Er3+ ions were also examined before and after annealing process. [ABSTRACT FROM AUTHOR]