Yb:CaF2-SrF2激光晶体光谱性能以及热学性能的研究

采用坩埚下降法生长了Yb: CaF₂-SrF₂晶体,测试了该晶体的吸收和荧光光谱 以及在不同温度下晶体的热扩散系数和热膨胀系数,并且计算了晶体的热膨胀系数以及在常温下的热导率. 采用对比的方法,对晶体的吸收光谱,荧光光谱,热学性能进行了分析.从吸收和荧光光谱结果表明: 在掺杂相对较高浓度的SrF₂的混晶中, Yb³⁺吸收截面和发射截面比较大. Yb: CaF₂-SrF₂ (19%)晶体在1040 nm附近的发射截面比较大,光谱也比较宽. 这说明在掺杂相同浓度Yb时,混晶中CaF₂, SrF₂的比例不同,晶体的光谱性质不同, 主要原因是在混晶中晶体的无序度不同,晶体对称性降低,形成低对称光学中心. 从热扩散系数计算的热导率结果看出晶体具有比较好的热导率.

Spectroscopic and thermal properties of Yb doped CaF2-SrF2 laser crystal

Yb: CaF₂-SrF₂ crystals are grown by Bridgman technique. The spectroscopic properties, thermal diffusion coefficients and thermal expansion coefficients at different temperatures are studied. Thermal conductivity at 300 K and thermal expansion coefficient are calculated. The absorption spectra, fluorescence spectra, thermal properties of crystals are analyzed by comparison method. The results show that the absorption and emission cross sections are larger in the high concentration SrF₂ disordered crystal. And also the emission cross section is large and wide at 1040 nm in the Yb: CaF₂-SrF₂ (19%) crystal. It demonstrates that for different ratios of CaF₂ and SrF₂ in the disordered crystals, the spectroscopic properties are different. The main possible reason is the different disorders, low symmetry, low symmetry optical centers in the disordered crystal. It can also be seen that the disordered crystal has a good thermal conductivity.