高斯镜参数对LD泵浦Nd:YAG激光器的影响

实验研究了输出镜为不同参数高斯镜时，偏心对LD泵浦Nd:YAG激光器的影响及激光器的输出特性。仅当光轴与激光晶体中心轴、Q开关中心轴一致，且经过高斯镜反射率中心时，可同时实现最大能量、最窄脉冲宽度和最小发散角输出。存在偏心时，高斯镜反射率半径越小或中心反射率越大，则能量下降越多，脉冲宽度和发散角增大越大。对于反射率半径为2.5 mm和中心反射率为30%的高斯输出镜，偏心0.5 mm时，能量降低7%，脉冲宽度增宽33%，发散角增大20%。激光性能方面，高斯镜反射率半径越小或中心反射率越小，光束质量越好，但效率低。综合考虑偏心影响和激光性能，反射率半径为2.75 mm和中心反射率为20%的高斯镜作为输出镜最佳。泵浦能量为984 mJ时，获得了能量128 mJ，脉冲宽度7.3 ns，光束质量M2因子约4.6的1064 nm激光输出，对应光光转换效率为13%。实验结果为激光器设计和装调提供了参考。

Influence of Gaussian mirror parameters on LD-pumped Nd:YAG laser

The influence of eccentricity and laser performance of LD-pumped Nd:YAG laser was investigated experimentally at different parameter Gaussian mirrors. Largest energy, narrowest width and smallest divergence can be obtained simultaneously only when the optical axis, laser crystal axis and Q-switch axis were in agreement, furthermore the optical axis went through the reflectivity center of Gaussian mirror. When eccentricity appeared, the energy, pulse width and divergence degraded more with smaller reflectivity radius or larger center reflectivity of Gaussian mirror. For 2.5 mm reflectivity radius and 30% central reflectivity Gaussian mirror, energy decreased 7%, pulse width increased 33%, and divergence increased 20% under 0.5 mm eccentricity. For laser performance, the smaller the reflectivity radius or center reflectivity of Gaussian mirror, the better the beam quality and the smaller the optical-to-optical efficiency. Considering the eccentricity influence and laser performance, 2.75 mm reflectivity radius and 20% center reflectivity Gaussian mirror was optimum. When the pump energy was 984 mJ, output energy of 128 mJ, pulse width of 7.3 ns, and beam quality M2 factor of 4.6 at 1064 nm were achieved, corresponding to the optical-to-optical efficiency of 13%. The experimental results in this paper can be a reference of the laser design and alignment.