利用激光诱导等离子体开关技术,对355 nm脉冲激光自削波进行了实验和理论研究。分别采用5种不同焦距的透镜,集中讨论了透镜焦距及激光器输出单脉冲能量对脉宽压缩的影响,发现采用焦距为200 mm的透镜能够获得最佳的脉冲压缩效果。在聚焦透镜焦距200 mm,单脉冲能量160 mJ时,获得最短脉宽3.47 ns;在激光电离Cu小孔内壁表面及空气击穿共同作用下,获得了脉宽最短达2.11 ns的脉冲激光输出。此外,根据实验结果得到了355 nm激光空气击穿阈值,并与理论估算值进行比较,两者结果较为一致。
An experimental and theoretical study on the wave clipping of 355 nm laser is conducted by using the laser induced plasma shutter technique. Five lenses with different focus are adopted to investigate the effects of the focus of lens and the laser pulse energies on pulse compression, and it is found that the best result can be obtained with the focus of 200 ram. While the focus of lens is 200 mm and the pulse energy is 160 mJ, the shortest pulse width of 3.47 ns is obtained. Under the ionization of the Cu pinhole and the atmospheric breakdown, the output pulse width can be further shortened to 2.11 ns. In addition, the measured atmospheric breakdown threshold induced by laser at 355 nm is in agreement with theoretical data.