Search

Er3+-doped glass based on TiO 2 –GeO 2 –BaO–Ga 2 O 3 has been examined for mid-IR luminescence applications. Mid-IR luminescence corresponding to the 4I 11/2 → 4I 13/2 transition of Er3+ is enhanced in the presence of TiO 2. These effects are stronger for mid-IR emission at 2727 nm than near-IR emission at 1533 nm related to the 4I 13/2 → 4I 15/2 transition of Er3+. The gain bandwidth for the 4I 11/2 → 4I 13/2 transition of Er3+ is relatively large (σ em × FWHM = 8.14 × 10−26cm3), which imply that glass with TiO 2 might be a promising candidate for efficient sources emitting mid-IR radiation. • Titanate-germanate glass doped with Er3+ has been studied for mid-IR emission. • Mid-IR luminescence at 2700 nm is enhanced significantly in the presence of TiO 2. • The relatively large gain bandwidth for the 4I 11/2 → 4I 13/2 transition of Er3+ is observed. [ABSTRACT FROM AUTHOR]

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]

Transparent Yb3+/Er3+ glass-ceramic was successfully obtained by the extrusion method. The extrusion of oxyfluoride tellurite-germanate glass co-doped with Yb3+ and Er3+ ions at 520 ℃ resulted in the formation of Ba0.75Er0.25F2.25 nanocrystals, leading to an increase in the upconversion (UC) emission intensity of 35 times in glass-ceramic with respect to the glass. The glass to glass-ceramic transition was confirmed by X-ray diffraction (XRD) and Transmission electron microscope (TEM). Also, the structural changes that occurred during crystallization were assessed using Fourier-transform infrared (FTIR) spectroscopy. Furthermore, the pump power and temperature UC emission dependence of glass and glass-ceramic under 976 nm laser excitation were investigated in detail. The assessments showed that i) two-phonons are involved in the UC process and ii) the temperature has a significant influence over it. The Yb3+/Er3+ codoped glass-ceramic shows relatively high Sa and Sr values in a wide temperature range from 300 to 573 K, presenting the maximal Sa value of 3.50 × 10-3 at 573 K and the maximal Sr value of 6.30 × 10-3 at 364 K. These results suggest that the glass-ceramic is a good candidate for optical applications such as luminescent thermometry. [ABSTRACT FROM AUTHOR]

• GeO 2 -TiO 2 -BaO-BaF 2 -Ga 2 O 3 system doped with Er3+, Tm3+, Ho3+ were synthesized. • The extremely low IR absorption coefficients were achieved. • Enhanced emission at 1.5 µm, 1.8µm and 2.0 µm by introducing BaF 2 in the composition was observed. • The luminescence lifetime significantly increased in the function BaF 2. • Optimal BaF 2 content in titanate-germanate glass was evaluated. A novel TiO 2 -GeO 2 -BaO-BaF 2 -Ga 2 O 3 glasses doped with rare-earth were synthesized, and the impact of the substitution of BaF 2 for BaO on properties has been investigated by luminescence spectroscopy. The IR absorption coefficient is extremely low, which is attractive for optical fibers emitting NIR radiation. Near-IR luminescence associated to the Er3+:4I 13/2 → 4I 15/2 (FWHM = 108 nm), Tm3+:3F 4 → 3H 6 (FWHM = 244 nm) and Ho3+:5I 7 → 5I 8 (FWHM = 179 nm) transitions are enhanced in the presence of BaF 2. Luminescence lifetimes increase with increasing content of BaF 2 in the glass composition. Fabricated optical materials with relatively high BaF 2 content represent a good starting point for further investigations in the field of glass technology and modern 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]

[Display omitted] • The physicochemical and optical properties of TiO 2 -modified barium gallo-germanate glasses co-doped with Er3+ and Yb3+ were characterized. • The near-IR luminescence at 1.5 μm (Er3+: 4I 13/2 → 4I 15/2) is enhanced significantly in the TiO 2 -GeO 2 -BaO-Ga 2 O 3 system. • Based on the lifetime values, the energy transfer efficiencies were estimated. • The effect of pair Yb3+/Er3+ was verified by the Stark splitting observed for hypersensitive Er3+:4I 15/2 → 2H 11/2 transition. • XRD analysis confirmed the presence of crystalline phases in the highly Yb3+ and Er3+ co-doped titanate-germanate samples with Yb 2 Ti 2 O 7 and Er 2 Ti 2 O 7 phases. This work combines photoluminescence methods, Raman spectroscopy, and X-ray diffraction (XRD) to expand the knowledge of the effects of pair rare earth ions doping on the physicochemical and near-IR properties of glasses. For this purpose, glass systems based on GeO 2 -BaO-Ga 2 O 3 (GBG) and TiO 2 -GeO 2 -BaO-Ga 2 O 3 (TGBG) doped with Er3+ ions (0.1, 0.25, 0.5 mol%) and Yb3+ ions (0.5, 1.25, 2.5 mol%) were synthesized and analyzed. The near-IR luminescence band corresponding to Er3+:4I 13/2 → 4I 15/2 is narrowed for germanate-based glasses (FWHM = 31 nm), whereas in the presence of TiO 2 is more intense and broadened (FWHM = 65 nm). The energy transfer efficiencies between Yb3+ and Er3+ ions in glass samples have been calculated. Notably, the absorption spectra showed the Stark splitting for the band due to the 4I 15/2 → 2H 11/2 hypersensitive transition. Finally, we find the formation of Er 2 Ti 2 O 7 and Yb 2 Ti 2 O 7 crystalline phases in highly doping titanate-germanate samples. The results provide valuable ideas to evaluate the effect of the rare earths doping procedure on properties of designed glasses for near-IR luminescence applications. [ABSTRACT FROM AUTHOR]