Ho^(3+)/Tm^(3+)共掺α-NaYF_4单晶体的光谱特性（英文）

Spectral Properties of Ho^(3+)/Tm^(3+)Co-dopedα-NaYF_4 Single Crystals

采用坩埚下降法生长出Ho^(3+)离子掺杂浓度~1.90 mol%、Tm^(3+)不同掺杂离子浓度(0.99mol%,1.58mol%,2.37 mol%,3.16 mol%,3.99 mol%,7.19 mol%)的双掺杂立方晶相NaYF_4单晶体.根据测定的吸收光谱以及800nmLD波长激发下的发射光谱、发射截面和衰减曲线,研究从Tm^(3+)离子到Ho^(3+)离子的能量传递机制、Tm^(3+)离子的浓度猝灭效应和Ho^(3+)离子在2.04μm波段的优化发光效应.当Ho^(3+)离子浓度保持为~1.90 mol%不变,Tm^(3+)离子浓度从0.99 mol%增加到1.59mol%时,2.04μm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.Ho^(3+)(1.90 mol%)/Tm^(3+)(1.59 mol%)共掺的单晶体的发射截面最大,达到2.17×10-20 cm^2,其荧光寿命最长,为21.72ms;同时,根据Ho^(3+)离子的吸收截面和Tm^(3+)离子的发射截面,计算得到该样品从Tm^(3+)∶3F^(3+)4→Ho∶5I7稀土离子能量传递系数和Ho^(3+)∶~5I_7→Tm^(3+)∶~3F_4反传递系数分别为C_(Tm-Ho)=24.14×10^(-40)cm^6/s,C_(Ho-Tm)=2.05×10^(-40) cm^6/s.

Cubic NaYF（3＋） 4single crystals co-doped with 1.90 mol% Hoand various Tm（3＋） 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 Tm（3＋） to Ho（3＋） ,concentration quenching of Tm（3＋） and the optimum fluorescence emission around 2.04μm of Ho（3＋） 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 2.04μm increased with the increasing（3＋） of Tmconcentration from 0.99mol%to 1.59mol%,and decreased with the increasing of Tm（3＋） concentration from 1.59mol%to 7.19mol% when the concentration of Ho（3＋） was held constantly at1.90mol%.Moreover,the maximum emission cross section reached to 2.17×10-20 cm2 and the maximum fluorescence lifetime was 21.72 ms for Ho（3＋） （1.90 mol%）/Tm（3＋） （1.59 mol%）co-doped one.At the same time,the energy transfer coefficients of this sample were calculated based on the absorption crosssection of Ho（3＋） and the emission cross-section of Tm（3＋） ,which is C_（Tm-Ho）=21.14×10（-40） cm6/s and C_（Ho-Tm）=2.05×10（-40） cm6/s respectively.