端面抽运方形复合YAG温度场及热透镜研究

采用数值方法研究了方形截面复合Nd∶YAG激光晶体棒在端面抽运情况下的温度分布及热透镜效应,得到复合激光晶体内温度场的数值解和径向温度梯度引起的轴向传播光相位延迟分布ΔΦT(r),并与同条件下普通晶体的结果进行了比较.结果表明,吸收系数越大,两种晶体中最高温度相差也越大.采用复合晶体可以大幅度降低激光晶体内的温升,同时减小端面形变造成的透镜效应.复合晶体的ΔΦT(r)与普通晶体相似,且不满足对半径r的二次方关系.在rwp时,ΔΦT(r)相对于参考球面透镜的相位畸变Δφ随r的增大而急剧增大.

Investigation on Temperature and Thermal Lens Effects of Laser Diode End Pumped Quadrate Composite YAG Crystal

Temperature field and thermal lens effects of laser diode end pumped quadrate composite Nd∶YAG rod are investigated through numerical analysis methods. Numerical solution of temperature field for end pumped configuration is obtained, as well as phase-retardation distribution ΔΦT(r) for the axial light caused by radial temperature gradient, and the results are compared with conventional crystal under the same pump condition. The results show that in both composite and conventional crystal, the differences of their highest temperature increase as the absorption coefficient increasing. Composite crystal leads a lower temperature rise in laser crystal, and also reduces the portion lens effect from the lessened distortion of pump end. ΔΦT(r) in composite crystal is similar to that of conventional one, and it does not accord with radius quadratic relationship. There is an aberration Δφ between the phase retardation of the thermal lens and referenced spherical lens. ΔΦT(r) corresponds with that of a spherical lens approximately at rwp.