Trines R M G M, Alves E P, Webb E, Vieira J, Fiúza F, Fonseca R A, Silva L O, Cairns R A, Bingham R
Central Laser Facility, STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK.
GoLP/IPFN, Instituto Superior Técnico, Universidade de Lisboa, 1049-001, Lisbon, Portugal.
Sci Rep. 2020 Nov 16;10(1):19875. doi: 10.1038/s41598-020-76801-z.
Raman or Brillouin amplification of a laser beam in plasma has long been seen as a way to reach multi-PW powers in compact laser systems. However, no significant plasma-based Raman amplification of a laser pulse beyond 0.1 TW has been achieved in nearly 20 years, and only one report of Brillouin amplification beyond 1 TW. In this paper, we reveal novel non-linear criteria for the initial seed pulse that will finally open the door to efficient Raman and Brillouin amplification to petawatt powers and Joule-level energies. We show that the triple product of the coupling constant [Formula: see text], seed pulse duration [Formula: see text] and seed pulse amplitude a for the Raman seed pulse (or [Formula: see text] for Brillouin) must exceed a specific minimum threshold for efficient amplification. We also analyze the plasma-based Raman and Brillouin amplification experiments to date, and show that the seed pulses used in nearly all experiments are well below our new threshold, which explains the poor efficiency obtained in them. Finally, we analyze a recent Brillouin amplification experiment that used increased seed pulse power to obtain Joule-level amplification, and find excellent agreement with our theory.
长期以来，等离子体中激光束的拉曼或布里渊放大一直被视为在紧凑型激光系统中实现多拍瓦功率的一种方法。然而，近20年来，尚未实现超过0.1太瓦的基于等离子体的激光脉冲拉曼放大，布里渊放大超过1太瓦的仅有一篇报道。在本文中，我们揭示了初始种子脉冲的新非线性准则，这最终将为实现太瓦功率和焦耳级能量的高效拉曼和布里渊放大打开大门。我们表明，拉曼种子脉冲的耦合常数[公式：见原文]、种子脉冲持续时间[公式：见原文]和种子脉冲幅度a的三重积（或布里渊的[公式：见原文]）必须超过特定的最小阈值才能实现高效放大。我们还分析了迄今为止基于等离子体的拉曼和布里渊放大实验，并表明几乎所有实验中使用的种子脉冲都远低于我们的新阈值，这解释了这些实验中获得的低效率。最后，我们分析了最近一个使用增加种子脉冲功率来实现焦耳级放大的布里渊放大实验，发现与我们的理论非常吻合。
