EAGER: Overcoming the Saturation Limit of High Intensity, Fully Coherent Raman Backscattering Laser

美国国家科学基金会使用探索性研究早期概念赠款（EAGER）资助机制，以支持未经测试但可能具有变革性的研究想法或方法的早期阶段的探索性工作。EAGER项目是由于在亲爱的同事信NSF 16-080中邀请来自历史上黑人学院和大学的提议者提交提案，以加强该机构教师的研究能力而获得的。特拉华州州立大学的该项目旨在研究通过受激拉曼背散射（SRBS）技术将超短激光脉冲的输出能量提高100倍以上的可行性。如果这个项目成功，它可以改变超高强度激光，这反过来又会产生巨大的技术和科学影响。 该项目将加强研究能力，并为学生提供等离子体物理学领域的教育机会。本项目由数学和物理科学理事会资助，一种替代目前啁啾脉冲放大的高功率激光器的方案是受激拉曼背散射（SRBS）方案，其中等离子体中的共振相互作用相干地介导能量从长泵浦到短得多的种子的转移。后向散射的短种子应该同时进行放大和压缩，并且由于等离子体不受光学损伤的影响，并且具有独特的色散特性，因此其功率可以增长到非凡的水平。从理论和实验上证明了SRBS激光器的可行性。尽管在过去十年中取得了一些进展，但由于早期饱和，最大放大脉冲能量仅限于毫焦耳水平。该项目通过综合理论、计算和实验方法解决SRBS中的障碍，旨在对早期饱和的潜在机制形成坚实的理论理解，通过模拟验证并通过实验证实;开发克服饱和极限的方案并证明饱和势垒可以解决;并演示了如何在毫米长的等离子体中通过移动孤子腔产生相干、单尖峰和单循环的拍瓦激光脉冲。

The National Science Foundation uses the Early-concept Grants for Exploratory Research (EAGER) funding mechanism to support exploratory work in its early stages on untested, but potentially transformative, research ideas or approaches. This EAGER project was awarded as a result of the invitation in the Dear Colleague Letter NSF 16-080 to proposers from Historically Black Colleges and Universities to submit proposals that would strengthen research capacity of faculty at the institution. The project at Delaware State University aims to examine the feasibility of increasing the output energy in ultra-short laser pulses by over 100 times via the Stimulated Raman Backscattering (SRBS) technique. If this project succeeds, it could transform ultra-high intensity lasers, which in turn would have great technological and scientific impact. The project will strengthen research capacity and provide educational opportunities to students in the area of plasma physics. This project is funded by the Directorate for Mathematical and Physical Sciences.An alternative to the present chirped pulse amplification for high power laser is the Stimulated Raman Backscattering (SRBS) scheme, where a resonant interaction in plasma coherently mediates energy transfer from the long pump into the much shorter seed. The backscattered short seed should undergo simultaneous amplification and compression, and since plasma is impervious to optical damage and has unique dispersion properties, its power can grow to extraordinary levels. Feasibility of SRBS lasers was demonstrated theoretically and experimentally. Still, despite some progress over the past decade, the maximum amplified pulse energy was limited to milli-joule levels due to early saturation. This project addresses obstacles in SRBS through an integrated theoretical, computational, and experimental approach, and aims to develop a solid theoretical understanding of the underlying mechanism for the early saturation, verified by simulation and confirmed with experiments; develop a scheme to overcome the saturation limit and prove that the saturation barrier can be resolved; and demonstrate how a coherent, single spiked, and single cycled petawatt laser pulse can be generated via a moving soliton cavity in a millimeter-long plasma.