两种国产新型掺Yb氟化物激光晶体的光谱特性研究

掺Yb氟化物激光材料是继掺Yb氧化物激光材料之后的另一类重要的掺Yb激光材料，已经成为可调谐激光和超快激光领域中研究的热点之一。针对两种国产新型掺Yb的氟化物激光材料：混晶材料Yb∶CaF₂-SrF₂和共掺离子型的单晶材料Yb, Y∶CaF₂，进行了详细的光谱特性比对实验研究。通过荧光比对实验，发现这两类激光材料的荧光光谱完全不同，并分析了不同荧光产生的物理机制。通过吸收率比对实验，讨论了两类材料中的激活离子Yb或共掺离子Y的掺杂浓度对晶体吸收特性的影响，得到了最佳掺Yb离子或共掺Y离子的浓度。利用激光二极管作为泵浦源，实现了这两类新型材料在折叠腔型下的连续激光输出运转，其中对于共掺离子型Yb, Y∶CaF₂晶体是首次实现连续激光运转。通过激光对比实验，获得了两类激光材料(四种样品)的激光输入—输出关系曲线，测量了各自的斜效率和激光光谱特征。通过系统地比较两类激光晶体的吸收率、荧光光谱特性、激光光谱特性以及连续激光运转的阈值功率和斜效率等参数得出以下结论：在四种实验样品中，共掺离子型单晶材料中的3at%Yb, 6at% Y∶CaF₂晶体具有最好的光谱和激光特性，具有良好的应用前景。这些实验结果为进一步提升此类激光材料的性能提供了有益的参考。

Study on Spectral Characteristics of Two Kinds of Home-Made Novel Yb-Doped Fluoride Laser Crystals

Yb-doped fluoride crystals are of important another Yb-doped laser materials besides Yb-doped oxide, which are becoming one of interests for developing tunable lasers and ultrafast lasers. In this paper, the systematic and contrastive experiments of the optical spectral characteristics are presented for two types of home-made novel Yb-doped fluoride laser crystals, namely, Yb-doped CaF₂-SrF₂ mixed crystal and co-doped Yb, Y∶CaF₂ single crystal. The fluorescent features of Yb-doped CaF₂-SrF₂ mixed crystal and co-doped Yb, Y∶CaF₂ single crystal are apparently different by the fluorescence experiment. The physical mechanism of these fluorescence spectra were analyzed and proposed. The influence of doping concentrations of active Yb3+ ions or co-doping Y ions on the absorption of Yb-doped CaF₂-SrF₂ mixed crystal and co-doped Yb, Y∶CaF₂ single crystal was experimentally investigated, and the optimal values of doping concentrations of active Yb3+ ions or co-doping Y ions in the two types of fluoride laser crystals were obtained. Continuous-wave laser operation for the two novel fluoride laser crystals has been achieved in three-mirror-folded resonator using a laser diode as the pump source. Therein, the laser operation for the co-doped Yb, Y∶CaF₂ crystal is demonstrated for the first time. For the two types of fluoride laser crystals (four samples), the input-output power relational curves, the optical slope efficiencies and the laser spectra were demonstrated by the laser experiments. By comparisons between the two types of fluoride laser crystals in the absorbability, fluorescence and laser spectra, laser threshold and slope efficiency of the continuous-wave laser operation, the results show that the best one of the four samples in spectral and laser characteristics is co-doped 3at%Yb, 6at% Y∶CaF₂ single crystal, which has an expected potential in the application. The research results provide available references for improving further laser performance of Yb-doped fluoride crystals.