The absorption spectra, fluorescence spectra and the lifetimes of 4I13/2 level of Er3+-doped phosphate and tellurite glasses ha ve been measured for sample with different concentrations and thickness. The abs orption cross-section (σa), emission cross-section(σe), spontaneous emission probability(Arad), radiative lifetime(τrad ) and quantum efficiency(η) of fluorescence around 1.53 μm of Er3+-doped phosphate and tellurite glasses were determined. The effect of radia tion trapping on the spectral properties and parameters of Er3+-doped tellurite and phosphate glasses has been investigated. It was found that radiat ion trapping exists generally in erbium-doped glass hosts, even at low Er3+ -doping concentration (0.1 mol% Er2O3). Due to radia tion trapping, the values of the τrad of the Er3+∶4 I13/2 level in tellurite glasses increased about 11%—37％ with the sample thickness and erbium doping concentration, while in phosphate glasse s τrad increased by 6%—17%. The full-width at half maximum (FWHM)of fluorescence in tellurite glasses increased about 15%—64%, with 11%—55% for p hosphate glasses. It caused a high overestimation on the figure of merits (FOM) for amplifier bandwidth (σe×FWHM). The spectral overlap between the emission and absorption spectra in 1.53 μm band is relatively larger in tellur ite than in phosphate glasses, and values of the emission cross-section in tellu rite glasses are larger than that in phosphate glasses. Consequently, the radiat ion trapping in tellurite glasses is more severel than that in phosphate glasses .

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Up to now, high-energy large-scale Yb3+ laser has still faced to the fact that no proper gain media are available, though researchers made a more than ten year effort for it. Yb: fluorophosphate glass is the only material used in a laser system, reaching an output of more than 10 TW. As is well known, the thermal blocking of Yb3+ laser is a bottleneck in laser operation, which is closely related to the Stark splitting of Yb3+ in a gain medium. Conventional Yb: phosphate glass has the advantages in Yb3+ concentration, lifetime and cross section over silicate glass, however, its small Stark splitting is the main drawback that induces difficulties in realizing laser output at room temperature. Yb: phosphate glass will be a good gain medium for high power Yb3+ laser if the Stark splitting is improved. This study focuses on the enlargement of the Yb3+ Stark splitting in phosphate glass by introducing SiO2, thereby achieving a large Stark splitting property compared with the phosphate glass. The glass 60P2O5-7.5Al2O3-15K2O-17.5BaO-1Yb2O3 is used as the base glass, and the modified glass denoted as PS is obtained by doping a certain amount of SiO2. Such a glass is prepared by the conventional melting-quenching method. Lorentz fitting is performed to the absorption and fluorescence spectra for determining the Stark splitting scheme. Raman spectrum is used for the auxiliary judgment of the attributions of the different spectroscopic bands. Then the results are confirmed by the barycenter law of Yb3+ ion. Investigations show that the addition of SiO2 can enlarge the Stark splitting obviously from the original 670 to 771 cm-1 in PS3. Scalar crystal field parameter N_{J} and asymmetry degree around Yb3+ are also increased due to SiO2 incorporation. Meanwhile, spectroscopic properties of PS series glasses, such as fluorescence effective line width (Δλeff) and fluorescence lifetime (τf), are moderately enhanced. The glass transition temperature is improved greatly, which is very valuable for high power Yb3+ laser. These results suggest that the introduction of a second network former is an effective way to enlarge the Stark splitting of Yb3+ in phosphate glass. Next, our investigation will focus on preparing the high-homogeneity SiO2 modified phosphate glasses and the corresponding laser experiments.

The color conversion glass is a promising material for light emitting diodes encapsulation due to its high thermal conductivity and good thermal stability. In present study, color conversion glasses were prepared by sintering a mixture of borosilicate glass frits and a YAG phosphor at temperature from 600℃ to 900℃. The effects of sintering temperature on luminescence properties were examined. Characteristics of color conversion glasses, with respect to luminescence intensity, CIE (Commission International de I'Eclairage) chromaticity and CCT (Correlated Color Temperature) were analyzed based on luminescence excitation and emission spectra. These characteristics are dependent on sintering temperature of the color conversion glasses. The CIE coordinates shift with increase of sintering temperature. The glass, sintered at 700℃, shows the best luminescence properties. But for the glasses sintered above 850℃, their luminescence properties may be destroyed. Test results of X-ray diffraction (XRD), differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS) reveal that degradation of luminescence properties with increase of sintering temperature is ascribed to the lattice disturbance of YAG and oxidation of Ce 3+ , which is caused