为了提高激光的光束质量和提供准直的平行光束，为抽运钛宝石提供优良的大功率的绿光抽运源，对激光二极管侧面抽运Nd∶YAG声光调Q腔内倍频固体激光器进行了研究。实验中采用凸平直线非稳腔，将凸面镜和增益介质热透镜效应等效为望远镜系统进行分析。由实验可知，凸平非稳腔具有较大模体积、良好的稳定性等优点；利用二类相位匹配的磷酸钛氧钾晶体进行腔内倍频，当抽运功率为200W时,获得脉宽109ns、重复频率9.3kHz、发散角小于2mrad的42W绿光输出，光光转换效率达到21％，24h长时间的工作，不稳定性小于2%。结果表明，利用非稳腔腔型，在侧面抽运的模块中可以实现高效的大功率绿光输出。

In order to improve its laser beam quality, obtain collimated laser beam and provide an excellent high-power green laser source to pump Ti∶sapphire, a diode-side-pumped acoustic-optic Q-switched intra-cavity frequency doubling Nd∶YAG laser was studied. In the experiment, a convex-plane unstable resonator was adopted assuming the convex mirrors and gain medium thermal lens as a telescope system. Experimental results show that a convex-plane unstable resonator has lager mode volume and better stability. Using a second type phase-matched KTP(KTiOPO4) for intra-cavity frequency doubling, with 200W pump power, 42W green laser was output with 109ns pulse width, 9.3kHz pulse repetition frequency, less than 2mrad divergent angle, 21% optical-optical conversion efficiency and instability less than 2% during 24h work. It is proven that an effective output of green laser can be achieved with an unstable resonator and side pump module.