光学学报, 2011, 31 (s1): s100410, 网络出版: 2011-06-23
强激光长程空气传输受激转动拉曼散射效应实验研究
Experimental Research on Stimulated Rotational Raman Scattering in Air with High-Power Laser
受激转动拉曼散射 发生阈值 能量损耗 近场光束质量退化 热斑 stimulated rotational Raman scattering threshold energy loss near field beam quality deterioration hot spots
摘要
研究了强激光长程空气传输过程中主光束能量损耗与光束质量退化效应。使用1053 nm单波长、线偏振、脉宽3 ns平顶激光脉冲于空气环境中长距离传输,当入射光强与传输距离乘积大于13.7 TW/cm时,传输末端测得的光束光谱分布中出现了多种散射光频率成分,各散射光成分和1053 nm主激光间的频率差与氮气分子不同转动能级间跃迁频率一致,证明氮气分子的受激转动拉曼散射效应已建立。受激转动拉曼散射过程中,入射光束功率密度微弱变化所产生的散射光能量变化剧烈。入射光强与传输距离乘积大于17 TW/cm时,传输末端光束近场分裂为无序密布特征尺寸约1 mm的热斑,峰值通量密度远高于入射光束通量密度。
Abstract
Propagation of high intensity laser beams through long air paths suffering from energy loss and beam quality deterioration was experimentally demonstrated. For linearly polarized, 3 ns flat-topped laser pulse at 1053 nm, when the intensity-path-length product of main laser pulse was above 13.7 TW/cm, the spectrum measured at the end of propagation showed the occurrence of stimulated rotational Raman scattering as frequency shifts from main laser of 1053 nm to the sideband components produced during propagation, corresponds to the transition between rotational states of nitrogen molecules. During the process of stimulated rotational Raman scattering, the energy loss will vary dramatically with even minor changes in the intensity of input laser pulse. Furthermore, the near field degrades to intense speckle pattern and thickly dotted hot spots with characteristic diameters about 1mm were observed at an intensity-length product above 17 TW/cm.
王静, 韩伟, 周丽丹, 李平, 向勇, 钟伟, 冯斌, 张小民. 强激光长程空气传输受激转动拉曼散射效应实验研究[J]. 光学学报, 2011, 31(s1): s100410. Wang Jing, Han Wei, Zhou Lidan, Li Ping, Xiang Yong, Zhong Wei, Feng Bin, Zhang Xiaomin. Experimental Research on Stimulated Rotational Raman Scattering in Air with High-Power Laser[J]. Acta Optica Sinica, 2011, 31(s1): s100410.