Lei Zhi-Yu, Sheng Zheng-Ming, Weng Su-Ming, Chen Min, Zhang Jie
Shanghai Jiao Tong University, National Key Laboratory of Dark Matter Physics, School of Physics and Astronomy, Shanghai 200240, China.
Shanghai Jiao Tong University, Laboratory for Laser Plasmas and Collaborative Innovation Centre of IFSA, Shanghai 200240, China.
Phys Rev Lett. 2025 Jun 27;134(25):255001. doi: 10.1103/cshj-jgz7.
Light amplification toward extremely high power in the infrared regime remains a significant challenge due to the lack of suitable gain media. Here we propose a new scheme to amplify a laser pulse with tunable wavelengths toward extremely high power via forward Raman amplification in plasma. Different from previously proposed schemes based upon backward Raman or Brillouin amplification, our scheme involves a pump pulse and a seed pulse copropagating in moderate density plasma, with the phase matching conditions for forward Raman scattering fulfilled. Due to their group velocity difference in plasma, the pump with a shorter wavelength and longer duration will chase the seed and transfer energy to the latter efficiently. Analytical models for both linear and nonlinear stages of amplification as well as particle-in-cell simulation show that, by employing a 1.0 μm pump laser, a 1.8 μm seed pulse can be amplified 10^{4} times in its intensity and then self-compressed to nearly single-cycle. Our scheme shows the merits of high efficiency, high compactness, and relatively easy implementation with the copropagating configuration, which may provide a unique route toward the petawatt few-cycle infrared laser pulses.
由于缺乏合适的增益介质，在红外波段实现极高功率的光放大仍然是一个重大挑战。在此，我们提出一种新方案，通过等离子体中的前向拉曼放大，将具有可调波长的激光脉冲放大到极高功率。与先前基于后向拉曼或布里渊放大提出的方案不同，我们的方案涉及一个泵浦脉冲和一个种子脉冲在中等密度等离子体中同向传播，满足前向拉曼散射的相位匹配条件。由于它们在等离子体中的群速度差异，波长较短、持续时间较长的泵浦脉冲将追逐种子脉冲并有效地将能量传递给后者。放大线性和非线性阶段的解析模型以及粒子模拟表明，通过使用1.0 μm的泵浦激光，一个1.8 μm的种子脉冲强度可以放大10⁴倍，然后自压缩到近单周期。我们的方案具有高效、高紧凑性以及同向传播配置相对易于实现的优点，这可能为拍瓦级少周期红外激光脉冲提供一条独特途径。
