为了提高Nd:YAG/LBO腔内倍频561 nm黄光激光器输出功率的稳定性，通过在谐振腔内插入双折射滤波器（BF）选择出单一谱线来实现。同时通过BF的角度调谐，分别得到了稳定的558 nm和556 nm单谱线输出。用5 W的激光二极管(LD)抽运Nd:YAG晶体，腔内加入2 mm厚的双折射滤波器，先通过BF放置角度的调谐获得单一谱线的基频光运转，再利用LBO晶体进行腔内倍频获得稳定的黄光输出。当抽运功率为时5 W时，556、558和561 nm激光的最大输出功率分别为256、189和227 mW，光光转换效率分别为5.12%、3.78%和4.54%。

In order to improve the stability of the 561 nm yellow laser output power by the Nd:YAG/LBO intra-cavity frequency doubling, the birefringence filter (BF) is inserted into cavity. Meanwhile, the 556 nm and 558 nm single line laser outputs are obtained by tuning the alignment angle of the BF. When the pumping power of Nd:YAG crystal is 5 W, and the thickness of BF is 2 mm, the fundamental beam of the single line laser is obtained by tuning the alignment angle of the BF. Then, the yellow laser is obtained by LBO intracavity-frequency-doubling. At the incident pumping power of 5 W, the output power at 556, 558, 561 nm are 256, 189, 227 mW, and the corresponding light-to-light conversion efficiency are 5.12%、3.78% and 4.54%, respectively.