Tm3+/Yb3+共掺碲酸盐玻璃的近红外发光及能量传递机理

采用高温熔融法制备了组分为TeO₂-ZnO-Na₂O的Tm³⁺离子单掺和Tm³⁺/Yb³⁺共掺碲酸盐玻璃,应用Judd-Ofelt理论计算分析了玻璃样品的强度参量Ω_t(t=2, 4, 6),自发辐射跃迁几率A,荧光分支比β和荧光辐射寿命τ_rad等光谱参量,测量得到了不同Yb³⁺离子掺杂浓度下玻璃样品的Tm³⁺离子上转换发光谱.结果显示,在980 nm泵浦光激励下玻璃样品发射出强烈的近红外上转换荧光.对Tm³⁺离子上转换发光分析表明,强烈的Tm³⁺离子近红外上转换发光主要来自于Yb³⁺/Yb³⁺离子间的共振能量传递以及基于单声子和双声子辅助的Yb³⁺/Tm³⁺离子间的非共振能量传递过程,并进一步计算得到了声子贡献比和能量传递系数.最后,计算分析了Tm³⁺:³F₄→³H₆能级间跃迁的1.8 μm波段吸收截面、受激发射截面和增益系数.研究表明,Yb³⁺/Tm³⁺共掺TeO₂-ZnO-Na₂O玻璃可以作为近红外波段固体激光器的潜在增益基质.

Near-infrared Emission and Energy Transfer Mechanism of Tm3+/Yb3+ Codoped Tellurite Glasses

Tm³⁺ single doped and Tm³⁺/Yb³⁺ codoped tellurite glasses with the composition of TeO₂-ZnO-Na₂O were prepared by melt-quenching method. The intensity parameters Ω_t(t=2, 4, 6), spontaneous radiative transition rates A, fluorescence branching ratios β and radiative lifetimes τ_rad of Tm³⁺ were calculated based on the Judd-Ofelt theory, and the upconversion luminescence of Tm³⁺ for glass sample with different Yb³⁺ doping concentration was measured. The results show that the glass sample can emit strong near-infrared upconversion emission under the excitation of 980nm pump light. The analysis of Tm³⁺ upconversion emission process reveals that the intense near-infrared upconversion luminescence of Tm³⁺ ions is mainly ascribed to the result of energy transfers: first the resonant energy transfer from Yb³⁺ to Yb³⁺ ions, and then followed by one and two phonon-assisted nonresonant energy transfer from Yb³⁺ to Tm³⁺ ions. The energy transfer coefficient and phonon contribution for the above energy transfer process were calculated. Furthermore, the 1.8μm band absorption, emission cross-sections and gain coefficient of Tm³⁺:³F₄→³H₆ transitions were calculated and analyzed. The research indicates that Yb³⁺/Tm³⁺ codoped TeO₂-ZnO-Na₂O glass is a promising host material applied for near-infrared band solid laser.