| Rare-earth(RE) ions doped glass materials have attracted considerable attention because of their potential applications in areas such as color display, optical storage, optical detectors, bulk lasers and optical fiber amplification. Among the various glass systems, tellurite glass represent a compromise between the demand for proper chemical durability and the desire for a low phonon energy host compared to other traditional glass systems such as silicate glass, borate glass and phosphate glass. In addition, tellurite glass exhibit high RE solubility and the addition of fluorine ions will increase the thermal stability and transparency of tellurite glass host, which is beneficial for applications in near-infrared optical amplifiers. In this work, the integrating sphere fluorescent test system coupled with a CCD detector was established and the whole measurement system was calibrated by a standard halogen lamp, and optical and spectral properties of Pr3+ were studied quantitatively. The integrating sphere-method was applied to measure absolute spectral parameters of the glasses, which directly illustrate the absolute power distribution of the emissions from Pr3+. The followings are results this work has achieved:1. Pr3+-doped fluorotellurite glass was designed and fabricated according to molar composition 4BaF2-4AlF3-16BaO-6La2O3-70TeO2(short for BABLT glass) with additional doping of 0.05wt% and 0.2wt% Pr6O11. The density and refractive index of the obtained glass samples were successfully measured.2. Thermal properties of fluorotellurite glass was characterized by the method of DTA, it was discovered that addition of fluoride can not only increase the thermal stability of the glass host but also the transparency of the glass, which leads to a high quantum yield of rare-earth ions in fluorotellurite glass.3. Judd-Ofelt parameters Ω2, Ω4 and Ω6 have been derived to be 3.96 × 10-20, 5.72 × 10-20 and 3.69 × 10-20cm2, respectively based on optical absorptions of Pr3+ in fluorotellurite glass. According to J-O parameters, other theoretical spectral properties such as oscillator strength, spontaneous emission probabilities, and branching ratio have been calculated. The spontaneous emission probabilities for 3P0â†'3F2,3P0â†'3H6,1D2â†'3H4 and 1D2â†'1G4 transitions were calculated to be 23265s-1,6088s-1,1426s-1,and 693s-1, respectively.4. Near-infrared 1474 nm emission corresponding to Pr3+:1D2â†'1G4 with a full width at half maximum of 120 nm have been observed. By fitting the decay curve, the measured lifetime of 1474 nm emission in 0.2wt% Pr6O11 doped fluorotellurite glass is derived to be 54.4μs. Thus, the quantum efficiency of the 1D2 level is calculated to be 33%.5. Adopting the integrating sphere measurement system coupled with a CCD detector, the fluorescence spectra of Pr3+ in fluorotellurite have been quantitatively determined and characterized. Under the excitation of a 457 nm blue commercial LED, the total radiant flux of 0.2wt% Pr6O11 doped BABLT glass was obtained to be 7900μW in the 380–780nm spectral region. In the 570–720nm spectral range of the fluorescence, it was solved to be 299μW and occupied 3.8% of the whole region. The total radiant flux of 0.05wt% Pr6O11 doped BABLT glass was obtained to be 8521μW in the 380–780nm spectral region. In the 570–720nm spectral range of the fluorescence, it was solved to be 147μW and occupied 1.7% of the whole region. The total quantum yield for the visible fluorescence of Pr3+ in 0.05wt% and 0.2wt% Pr6O11 doped has been calculated to be 9.53% and 14.94%, respectively. Quantitative characterization provides basis for the further development of rare-earth ions doped optical devices and solid fluorescence materials. |
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