从实验和理论两方面分析了808 nm和885 nm激光二极管(LD)端面抽运Nd∶CNGG 935 nm激光器的热透镜效应。当吸收功率为10 W时，在885 nm LD端面抽运情况下，Nd∶CNGG激光器的热透镜焦距约为808 nm LD端面抽运方式下的6.8倍。同时，利用885 nm LD端面抽运方式，晶体内部的温度梯度更小。利用808 nm和885 nm LD端面抽运方式，在抽运光束腰位置，Nd∶CNGG晶体内部最高温度分别为287.76 K和310.05 K。在抽运端面位置，晶体最高温度分别为285.78 K和317.18 K。相对于同等实验条件下的808 nm抽运方式，885 nm抽运下的Nd∶CNGG 935 nm激光器斜率效率提高了43%(从4.6%提高到6.6%)，阈值降低了8%(从3.31 W下降到3.05 W)。

The thermal lensing effects of 808 nm and 885 nm LD end-pumped NdCNGG 935 nm laser are investigated by experimental and theoretical methods. The thermal focal length of the laser pumped by 885 nm is about 6.8 times of the one pumped by 808 nm when the absorbed power reaches to 10 W. Meanwhile, the temperature gradient in crystal is smaller under 885 nm pumping. At the pump waist position, the maximal values of the crystal temperature under 885 nm and 808 nm pumping are 287.76 K and 310.05 K, respectively, in experiment. At the pump face, the maximal values of the crystal temperature under 885 nm and 808 nm pumping are 285.78 K and 317.18 K. Compared with the 808 nm pumping scheme, the slope efficiency increases by 43% (from 4.6% to 6.6%) with an 8% reduction (from 3.31 W to 3.05 W) in the oscillation threshold under 885 nm direct pumping scheme.