Weaver James, Lehmberg Robert, Obenschain Stephen, Kehne David, Wolford Matthew
Appl Opt. 2017 Nov 1;56(31):8618-8631. doi: 10.1364/AO.56.008618.
Stimulated rotational Raman scattering (SRRS) in the ultraviolet region (λ=248 nm) has been observed at the Nike laser over extended propagation paths in air during high power operation. Although this phenomenon is not significant for standard operating configurations at Nike, broadening of the laser spectrum and far-field focal profiles has been observed once the intensity-path length product exceeds a threshold of approximately 1 TW/cm. This paper presents experimental results and a new theoretical evaluation of these effects. The observations suggest that significantly broader spectra can be achieved with modest degradation of the final focal distribution. These results point to a possible path for enhanced laser-target coupling with the reduction of laser-plasma instabilities due to broad laser bandwidth produced by the SRRS.
在高功率运行期间，在耐克激光器上于空气中的扩展传播路径上观测到了紫外区域（λ = 248 nm）的受激旋转拉曼散射（SRRS）。尽管这种现象在耐克激光器的标准运行配置中并不显著，但一旦强度 - 路径长度乘积超过约1 TW/cm的阈值，就会观察到激光光谱展宽和远场焦斑分布变化。本文给出了这些效应的实验结果和新的理论评估。观测结果表明，在最终焦斑分布适度退化的情况下，可以实现显著更宽的光谱。这些结果指出了一条可能的途径，即通过减少由SRRS产生的宽激光带宽引起的激光 - 等离子体不稳定性，来增强激光与靶的耦合。
