氟化钙(CaF2)是一种良好的激光材料基质,具有较宽的透过范围(0.125~10μm)、良好的导热性(9.71 W/(m·K))和低非线性效应系数.在Pr:CaF2晶体中,[Pr3+-Pr3+]团簇导致Pr3+离子在较低浓度下出现荧光猝灭现象.在CaF2中共掺入La3+离子有可能打破[Pr3+-Pr3+]团簇.本研究通过温度梯度法(Temperature Gradient Technique,TGT),成功地生长了一系列共掺入不同浓度La3+离子的Pr:CaF2晶体.在室温下采用X射线粉末衍射、吸收光谱、荧光光谱和荧光衰减寿命对Pr,La:CaF2晶体进行表征.Pr:CaF2晶体共掺入La3+离子后仍具有立方晶体结构.3P0→3H6(604 nm)和3P0→3F2(640 nm)处的最大受激发射截面分别为1.36×10–20和3.18×10–20 cm2,半峰宽分别为17.0和3.8 nm.随着La3+离子掺杂含量的增加,3P0→3H6(604 nm)处的半峰宽从15.84增加到18.53 nm.0.6%Pr,10%La:CaF2(原子分数)的最大荧光寿命和光谱质量因子分别为45.82μs和145.8×10–20 cm2·μs.上述结果表明:[Pr3+-Pr3+]离子淬灭团被打破,Pr,La:CaF2晶体是潜在的激光增益材料,可应用于橙红色激光领域.
Calcium fluoride (CaF2) is an attractive laser material due to its broad transmission range (0.125–10 μm), good thermal conductivity (9.71 W/(m·K)) and low coefficient of nonlinear effect. In Pr:CaF2 crystal, the [Pr3+-Pr3+] cluster lead to fluorescence quenching at lower concentrations of Pr3+ ions. Therefore, co-doping of La ions in CaF2 to break the [Pr3+-Pr3+] cluster deserves further exploration. In this work, a series of Pr:CaF2 single crystals co-doped with different concertation of La3+ ions were successfully grown by temperature gradient technique (TGT). The X-ray powder diffraction, absorption spectra, fluorescence spectra and fluorescence decay lifetime of Pr,La:CaF2 crystals were measured. Obtained data demonstrated that the Pr:CaF2 crystals still had the cubic crystal structure after co-doped with La3+ ions. The largest stimulated emission cross-sections of 3P0→3H6 (604 nm) and 3P0→3F2 (640 nm) transitions were calculated to be 1.36×10–20 cm2 and 3.18×10–20 cm2 with FWHM of 17.0 nm and 3.8 nm, respectively. With the increase of La3+ ion concentration, the value of FWHM increased from 15.84 nm to 18.53 nm of 3P0→3H6. The largest fluorescent lifetime and spectral quality factor of 0.6%Pr, 10%La:CaF2 (atom fraction) is 45.82 μs and 1.458×10–18 cm2·μs, respectively. All above results show that the [Pr3+-Pr3+] ions quench clusters are broken by La3+ ions. The Pr, La:CaF2 crystal is a potential laser gain material for orange-red laser operation.