Tm3+/Ho3+共掺碲酸盐玻璃的中红外发光及能量传递机理

用高温熔融法制备了Tm3+/Ho3+共掺碲酸盐玻璃(TeO2-ZnO-Na2O),根据测量得到的吸收光谱,应用Judd-Ofelt理论计算分析了玻璃样品中Ho3+离子的强度参数Ωt(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τrad等各项光谱参数。同时,测量得到了不同Ho3+离子掺杂浓度下玻璃样品的荧光发射谱。结果显示,在808nm抽运光激励下Tm3+/Ho3+共掺碲酸盐玻璃样品发射出较强的2.0μm中红外荧光。分析表明,较强的Ho3+离子中红外荧光来自于Tm3+/Tm3+离子间共振的能量传递过程,以及Tm3+/Ho3+离子间基于零声子和单声子辅助非共振的两部分能量传递过程。由此进一步计算得到了Tm3+/Tm3+、Tm3+/Ho3+离子间的能量传递微观速率、临界半径和声子的贡献。最后,计算分析了Ho3+…5I7→5I8能级间跃迁的2.0μm波段吸收截面、受激发射截面和增益系数。研究表明,Tm3+/Ho3+共掺TeO2-ZnO-Na2O玻璃可以作为2.0μm波段中红外固体激光器的潜在增益基质。

Mid-Infrared Luminescence and Energy Transfer Mechanism of Tm3+/Ho3+ Co-Doped Tellurite Glasses

Tm3+/Ho3+ co-doped tellurite glasses with the composition of TeO2-ZnO-Na2O are prepared by the high temperature melt-quenching method. The intensity parameters Ωt(t=2,4,6), spontaneous radiative transition rates A, fluorescence branching ratios β and radiation lifetimes τrad of Ho3+ are calculated from the measured absorption spectra with the Judd-Ofelt theory. Meanwhile, the fluorescence spectra of glass samples with different doped concentration of Ho3+ ions are measured, and the results show the intense mid-infrared fluorescence emission around 2.0 μm band in the Tm3+/Ho3+ co-doped tellurite glasses pumped by 808 nm diode laser. The analysis indicates that the mid-infrared emission of Ho3+ ions is mainly the result of resonant energy transfer from Tm3+ to Tm3+ ions, and then zero phonon- and one phonon-assisted nonresonant energy transfer from Tm3+ to Ho3+ ions. The energy transfer micro-rates, critical radius and phonon contributions for the above energy transfer process are calculated and analyzed. Meanwhile, the absorption, stimulated emission cross-sections and gain coefficient of Ho3+5I7→5I8 transitions are calculated. The research shows that Tm3+/Ho3+ co-doped TeO2-ZnO-Na2O glass is a promising host material applied for 2.0 μm-band mid-infrared solid laser.