用声光调制器实现的1 W Nd∶YAG单纵模环形激光器

鉴于单向环形腔是目前获得较大功率单纵模激光最有效的方式之一，为使环形腔单向运行，需要在环形腔内插入对正反2个方向的光产生损耗差的光学元件。采用激光二极管泵浦Nd∶YAG晶体，用声光调制器作为光学二极管使环形腔单向运行，实现四镜矩形环形腔单纵模激光器。实验中谐振腔的稳定性由增益介质的热透镜保证，声光调制器给正反2个方向的光提供损耗差，这使得在竞争过程中有较大损耗的光不能运行从而获得单向输出。实验获得了连续功率1 W、光束质量因子M2为1.21 的1.06 m单纵模激光。

1 W Nd-YAG single-longitudinal-mode ring laser using acousto-optic modulator

Using unidirectional ring resonator is the most promising way to get high power single-longitudinal-mode (SLM) laser output. To enforce the single longitudinal-mode ring cavity to operate unidirectionally, a component which can introduce loss difference between the counter-propagating beams in the cavity is necessary. A diode-pumped Nd∶YAG SLM four-mirror rectangle ring laser was experimentally demonstrated. The stability of the cavity was ensured by the thermal of the gain medium, and an intra-cavity acousto-optic modulator was used as the optical diode, which provided different losses on the counter propagating beams. The beam with larger loss died out in their competition for the gain and hence the unidirectional operation was demonstrated. An SLM output power of 1 W at 1.06 μm with a beam quality factor M2 of 1.21 was obtained. The considerable increased output power and compact architecture are especially important for future practical application.