给出一测量激光二极管(LD)端面抽运固体激光器稳态运转时腔内激活介质热透镜焦距的简便方法.采用混合模类高斯光束描述激光器输出镜后的光场分布,通过一狭缝在不同位置横向扫描光场来测得光束的光斑尺寸和描述光束的质量因子M2,根据混合模类高斯光束传播规律推导出光束的束腰及在相同激光器参数下对应的基模高斯光束束腰的大小,由此利用稳定谐振腔标准传输矩阵理论可得到相应的激光介质的热透镜焦距.基于上述测量原理,对LD端面抽运Nd∶YVO4固体激光器热透镜焦距进行了测量,实验结果和理论分析相符.

A simply method to measure the thermal focal length of LD end pumped solid state lasers with stable resonators was presented. By scanning the slit across the field with expression of multi mode Gaussian distribution behind the output mirror of lasers, the radius and the M 2 factor describing the quality of beam were measured. The waist of the multi mode field and the TEM 00 mode at the same parameters of lasers could be deduced according to the law of multi mode Gassian beam propagation. Based on the standard matrix theory of stable resonator, the thermal focus length of the active medium was easily obtained. The thermal focal length of a LD end pumped Nd∶YVO 4 laser was measured and the experimental results were agreed with the prediction of the theory.