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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]

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]

• 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]

[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]