Investigation of defect, mechanical, thermal properties and refractive index on an Er:LuYSGG mixed laser crystal

We investigate the defect, mechanical, thermal properties, and refractive index of Er:LuYSGG mixed crystal grown by the Czochralski method. The chemical etching pit patterns present a regular tetrahedron, which consists well with the corresponding atomic arrangement schematics. The Mohs hardness is obtained to be 6.60. The thermal expansion coefficient and the thermal conductivity along <111> crystallographic orientation are achieved to be 7.91×10-6 K-1 and 3.423 W m-1 K-1, respectively, indicating the Er:LuYSGG has a relatively high damage threshold. Based on the measured values of refractive index, the Sellmeier equation is fitted and the refractive index curve in the range of 400-3000 nm is displayed. All these results are of great significance for the further research and laser application of Er:LuYSGG crystal.

本研究针对提拉法（Czochralski method）生长的Er:LuYSGG混晶的缺陷、力学、热学性能及折射率展开了系统表征。化学腐蚀坑形貌呈现规则四面体结构，与对应的原子排布示意图高度吻合。测得该晶体的莫氏硬度为6.60。沿<111>晶向的热膨胀系数与热导率分别为7.91×10^-6 K^-1和3.423 W·m^-1·K^-1，表明该Er:LuYSGG混晶具有较高的激光损伤阈值。基于实测的折射率数据，拟合得到塞勒迈尔方程（Sellmeier equation），并绘制了400~3000 nm波段内的折射率变化曲线。上述研究结果对于该混晶的后续研究及激光应用具有重要意义。