半导体抽运[100]和[111]切割方向Nd：YAG激光器被动调Q实验的研究

Investigation of Diode Pumped Passively Q-Switched [100]- and [111]-Cut Nd：YAG Laser

热应力双折射产生的热退偏是限制Nd=YAG激光器线偏振输出功率的重要因素，相比于传统[111]切割方向Nd：YAG晶体，E100]切割方向Nd：YAG晶体的热退偏与振荡光偏振方向有关，通过寻找合适的偏振方向，能够显著提高[100]切割方向Nd：YAG激光器的线偏振输出功率。采用半导体端面抽运[111]和[100]切割方向的Nd：YAG晶体棒，使用Cr4＋：YAG晶体作为被动调Q晶体，进行被动调Q对比实验研究。实验结果表明，相比于传统的[111]切割方向Nd：YAG晶体棒，采用半导体抽运[100]切割方向Nd：YAG晶体棒进行被动调Q，能够获得稳定、高消光比的线偏振光激光输出，输出激光消光比为500：1，稳定度高于96．5％。

Thermal depolarization caused by birefringence is a major factor that limits the output power of linearly polarized Nd： YAG laser. Compared with conventional [111]- cut Nd4＋ YAG rod, the thermal depolarization depends on the polarization direction for the [1001- cut Nd：YAG rod. The linearly polarized output power can be improved by suitable modification of the polarization direction of oscillate laser. The [111]- and [100]- cut Nd： YAG rods are used as the gain medium and the Cr4＋ ：YAG crystal is used as the saturable absorber for passively Q-switched laser. The experiment demonstrates that in comparison with conventional [111]- cut Nd~ YAG rod, highly stabled output with high extinction is achieved by using the [100]- cut Nd4＋ YAG rod as the laser crystal. The extinction ratio is 500：1 and polarized output stability is higher than 96.5 %.