Nd:YVO_4晶体π和σ偏振激光的实现及性能研究

Realization and Performance Study of π-and σ-Polarization Laser of Nd:YVO_4 Crystal

利用偏振分束器(PBS)选择性地实现a轴切割Nd:YVO_4晶体π和σ偏振的激光输出的实验研究。四方晶系Nd:YVO_4晶体偏振荧光光谱的差异,导致了输出π和σ偏振激光的性能差别。实验中利用PBS的反射光束主动选偏,结合激光晶体沿通光方向旋转,分别对a轴切割Nd:YVO_4晶体的~4F_(3/2)～~4I_(11/2)和~4F_(3/2)～~4I_(13/2)能级跃迁的偏振激光性能进行测试。在11 W的入射抽运功率下,基于~4F_(3/2)～~4I_(11/2)能级跃迁分别获得了5.5 W的π偏振1064.3nm激光输出和4.4 W的σ偏振1066.7nm激光输出;基于~4F_(3/2)～~4I_(13/2)能级跃迁分别获得了2.9 W的π偏振激光输出和1.6 W的σ偏振激光输出,但波长均为1341.8nm。实验结果表明:a轴切割Nd:YVO_4晶体的π偏振激光输出有更高的转换效率,而σ偏振激光输出则有更长的激光谱线。

π- and σ polarization laser emission in a cut Nd： YVO4 crystal are selectively realized with a polarization beam splitter （PBS）. The difference of polarized fluorescence spectra of tetragonal Nd： YVO4 crystal results in the performance difference between the π- and σ-polarization laser outputs. The π- and σ-polarization laser performances of a-cut Nd： YVO4 crystal with 4 F3/2 to 4 I11/2 and 4 F3/2 to 4 I13/2 energy level transitions are investigated by rotating the laser crystal along the optical direction and active polarization selection of PBS reflected beam. When the pump power is 11 W, π-polarization laser at 1064.3 nm with output power of 5.5 W and o polarization laser at 1066.7 nm with output power of 4.4 W are obtained for the 4F3/2 4I11/2 energy level transition, respectively. While for the 4 F3/2-4 I13/2 energy level transition, π polarization laser at 1341.8 nm with output power of 2.9 W and o-polarization laser at 1341.8 nm with output power of 1.6 W are obtained, respectively. The experimental results show that the π-polarization laser has higher conversion efficiency and the o-polarization laser owns longer laser spectrum for a cut Nd： YVO4 crystal.