为了研究复合Nd∶YAG激光晶体棒在端面抽运下的温度分布及热透镜效应，采用数值分析法得到了端面抽运激光晶体棒内温度场的数值解，当抽运光功率为18W、光斑半径0．2mm时，吸收系数为3．5／cm的复合晶体内最大温度为73．8℃；同时还得到了径向梯度折射率引起的轴向传播光相位延迟分布△Φ_t(r)，并与相同条件下的普通晶体作了比较。结果表明，采用复合晶体可以大幅度降低激光晶体内的温升，并减小端面变形导致的透镜效应；复合晶体内的相位延迟分布△Φ_t(r)与普通晶体的相似，且不满足对半径r的二次方关系；热透镜和参考球面镜透镜的相位延迟分布之间存在畸变△φ，在r较小(r＜w_p)时，相位延迟分布△Φ_t(r)可近似等效于一球面透镜，其等效焦距f_GRIN值与普通晶体的接近，在r较大(r＞w_p)时，畸变△φ随r增大而急剧增大。

Temperature field and thermal lens effect of laser diode end pumped composite Nd∶ YAG rod were investigated through numerical analysis methods. Numerical solutions of temperature field were obtained. The maximum temperature was 73.8℃ for composite laser crystal with an absorption coefficient of 3.5/cm,under pump power of 18W with 0.2mm beam radius.And also phase-retardation distribution △Φ_t(r)of the axial transmission light caused by radial temperature gradients was obtained. Comparing with conventional rod,the results show that composite rod leads a lower temperature rise in laser rod,as well as reduces distortion of pump end which brings on lens effect of laser crystal. Phase-retardation distribution △Φ_t(r)in composite rod is similar to that of conventional laser rod,but it doesn't accord with radius quadratic relationship,there is an aberration △Φ between the phase retardation of the thermal lens and referenced spherical lens. △Φ_t(r)corresponds with that of a spherical lens approximately at r ＜w_p,and the equivalent foci f_GRIN approaches to the same value of conventional rod,whereas △Φ increases quickly with the increase of laser beam radius at r＞ w_p.