采用坩埚下降法生长出Ho3+离子掺杂浓度~1.90 mol%、Tm3+不同掺杂离子浓度(0.99 mol%, 1.58 mol%, 2.37 mol%, 3.16 mol%, 3.99 mol%, 7.19 mol%)的双掺杂立方晶相NaYF4单晶体.根据测定的吸收光谱以及800 nmLD波长激发下的发射光谱、发射截面和衰减曲线, 研究从Tm3+离子到Ho3+离子的能量传递机制、Tm3+离子的浓度猝灭效应和Ho3+离子在2.04 μm波段的优化发光效应.当Ho3+离子浓度保持为~1.90 mol%不变, Tm3+离子浓度从0.99 mol% 增加到 1.59 mol%时, 2.04 μm波段的发射强度逐步增强；当浓度从1.59mol% 增加到7.19mol%时, 发射强度逐步减弱.Ho3+(1.90 mol%)/Tm3+(1.59 mol%)共掺的单晶体的发射截面最大, 达到2.17×10－20 cm2, 其荧光寿命最长, 为21.72 ms；同时, 根据Ho3+离子的吸收截面和Tm3+离子的发射截面, 计算得到该样品从Tm3+∶3F4→Ho3+∶5I7稀土离子能量传递系数和Ho3+∶5I7→Tm3+∶3F4反传递系数分别为CTm-Ho=24.14×10－40 cm6/s, CHo-Tm=2.05×10－40 cm6/s.

Cubic NaYF4 single crystals co-doped with ~1.90 mol% Ho3+ and various Tm3+ concentrations (0.99mol%, 1.58 mol%, 2.37 mol%, 3.16 mol%, 3.99 mol%, 7.19 mol%) were grown by using the Bridgman method. The energy transfer from Tm3+ to Ho3+, concentration quenching of Tm3+ and the optimum fluorescence emission around 2.04 μm of Ho3+ ion were investigated based on the measured absorption spectra, emission spectra, emission cross section and decay curves under excitation of 800 nm LD. The emission intensity at 2.04 μm increased with the increasing of Tm3+ concentration from 0.99 mol% to 1.59 mol%, and decreased with the increasing of Tm3+ concentration from 1.59 mol% to 7.19 mol% when the concentration of Ho3+ was held constantly at ~1.90 mol%. Moreover, the maximum emission cross section reached to 2.17×10－20 cm2 and the maximum fluorescence lifetime was 21.72 ms for Ho3+(1.90 mol%)/Tm3+(1.59 mol%) co-doped one. At the same time, the energy transfer coefficients of this sample were calculated based on the absorption cross-section of Ho3+ and the emission cross-section of Tm3+, which is CTm-Ho=21.14×10－40 cm6/s and CHo-Tm=2.05×10－40 cm6/s respectively.