Yb3+/Er3+共掺锗碲酸盐玻璃上转换发光增强机理的研究

玻璃的最大声子能量决定稀土离子的上转换发光强度，但本研究发现：Yb³⁺/Er ³⁺共掺锗碲酸盐玻璃在980nm LD抽运下，上转换荧光强度随着Bi₂O ₃对PbO的取代和碱 金属离子半径的增大而明显增强.而Raman光谱显示基质玻璃的最大声子能量并不随Bi ₂O₃对PbO的取代和碱金属离子半径的增大而变化，但玻璃的最大声子密 度随着Bi₂O₃对PbO 取代和碱金属离子半径的增大而降低.从玻璃无辐射跃迁概率的角度，通过分析表明，最大 声子密度的降低是玻璃上转换发光强度增强的主要原因.

Mechanism of the enhanced upconversion emissions in Yb3+/Er3+-codoped germanate-tellurite glasses

The intensity of upconversion emissions of rareearth ions is determined by the maximum phonon energy of glass host. In this paper the intensities of upconversion emissions in Yb³⁺/Er³⁺codoped germanatetellurite glas ses upon the excitation of 980nm laser diode were extremely enhanced by replacing PbO wit h Bi₂O₃ and increasing the size of alkalimetal ions. Rama n spectra show tha t the maximum phonon energies of the glass hosts investigated keep unchanged, wh ile the maximum phonon density decreases on substituting Bi₂O_{3 for PbO and i ncreasing the size of alkalimetal ions. Based on the nonradiative decay rate, it is found that the maximum phonon density is the main reason for the enhanceme nt of upconversion emissions in Yb³⁺/Er³⁺codoped germana tetellurite glasses.}