We have numerically analyzed the thermal effects in Nd: YLF laser rod. The calculations of temperature and stress distributions in the Nd: YLF laser rod were performed with finite element (FE) simulations. The calculations showed that the laser rod could be pumped up to a power of 40 W without fracture caused by thermal stress. The calculated thermal lens power of thermally induced lens in Nd: YLF (σ-polarization) laser rod was analyzed and validated experimentally with two independent techniques. A Shack-Hartmann wavefront sensor and a Mach-Zehnder interferometer were used for direct measurements of focal thermal lens at different pump powers. The obtained measurements were coinciding with the FE simulations.

利用Yb³⁺∶KGd(WO₄)₂晶体的热膨胀系数各向异性和折射率温度梯度为负值的特点，就可能找到被光抽运时热透镜效应为零的特定方向，此方向即为“无热透镜方向”。鉴于前人的理论计算中存在着一些缺陷，利用最小二乘法和二阶张量旋转法，精确计算了Yb³⁺∶KGd(WO₄)₂晶体的热膨胀张量以及在不同偏振状态下的无热透镜方向：m偏振时，在p-g 平面内与p 轴成±46.3°的方向；p 偏振时，在m-g 平面内与m 轴顺时针成24.9°以及与m 轴逆时针成81.2°的方向；g 偏振时不存在无热透镜方向。将之与前人的计算结果进行了比较，指出了其理论模型中存在的缺陷。计算了p 偏振时在m-g 平面内与m 轴顺时针成17°的方向上传播以及m 偏振时b 方向传播的单位光程变化值，并与前人已发表的理论与实验结果做了对比分析，证实了所建理论体系的有效性。