用双折射晶体相位延迟法选纵模的理论分析和实验研究

Theoretic Analyses and Experimental Investigation on Selecting SLM by Phase Delay of a Birefingent Crystal

提出了一种新的固体激光器纵模选择技术，分析了该方法的损耗调制原理，用半经典理论建立二模光场竞争的运动方程，并对这种方法的纵模选择能力进行了计算。实验中用ＫＴＰ和方解石两种双折射晶体都实现了固体激光器的单纵模振荡，用ＫＴＰ晶体获得了ＣＷ４４ｍＷ的单纵模激光输出，稳定性优于±３％。实验表明在半导体激光泵浦的中小功率固体激光器中用该方法选纵模具有稳定、可靠的优点。

In the paper, a new technology for selecting single longitudinal mode (SLM) of solid state laser by phase delay of a birefingent crystal is proposed. Its principles of loss modulation are analysed. Based on the semiclassical theory, dynamic equations of light field are derived when several longitudinal modes compete in a cavity. Its ability for selecting mode is calculated. The oscillation of SLM is experimentaly demonstrated in a solid state laser by this way. The output power of 44 mW and stability of ±3% are obtained by using KTP crystal. It is shown that this technology is preferable to selecting SLM in diode pumped solid state laser with mid lower output power.