非均匀等离子体中的啁啾脉冲前向拉曼放大
Chirped-Pulse Forward Raman Amplification in Nonuniform Plasmas
- Shanghai Jiao Tong University（上海交通大学）
- National Key Laboratory of Dark Matter Physics, School of Physics and Astronomy, Shanghai Jiao Tong University（暗物质物理全国重点实验室，上海交大物理与天文学院）
- Laboratory for Laser Plasmas and Collaborative Innovation Centre of IFSA, Shanghai Jiao Tong University（激光等离子体实验室及IFSA协同创新中心，上海交大）
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University（李政道研究所，上海交大）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出在非均匀等离子体中采用正啁啾种子脉冲的前向拉曼放大方案，通过动态补偿相位失谐实现宽带放大，可将约10%带宽的种子脉冲放大1e7倍，为等离子体光放大实际应用奠定基础。
AI中文摘要：
等离子体中的拉曼散射光放大长期受到严格的相位匹配条件和等离子体均匀性要求的严重限制。为克服这些局限，本文提出一种前向拉曼放大方案，该方案采用正啁啾种子脉冲，与泵浦脉冲在具有上升密度轮廓的非均匀等离子体中同向传播。研究表明，等离子体非均匀性诱导的相位失谐可得到动态补偿，从而实现种子脉冲整个光谱带宽上的宽带放大；同时，由于等离子体的空间色散变化，啁啾脉冲的持续时间会持续压缩。本文构建了包含失谐项的理论模型，并得到粒子模拟（PIC）仿真的支持，阐明了该补偿机制。结果显示，初始带宽约10%的啁啾种子脉冲，在陡峭密度上升段的皮秒时间尺度内可被直接放大1e7倍，达到超过1e17W/cm²的强度。该方案为推进基于等离子体的光放大走向实际应用奠定了新的基础。
英文摘要：
Light amplification via Raman scattering in plasma has been severely constrained by stringent phase matching conditions and the need for plasma uniformity. To overcome these limitations, we propose a forward Raman amplification scheme that employs a positively chirped seed pulse co-propagating with a pump pulse in a nonuniform plasma with an upramp density profile. We demonstrate that the phase detuning induced by plasma nonuniformity can be dynamically compensated, enabling broadband amplification across the entire spectral bandwidth of the seed pulse. Concurrently, the chirped pulse duration undergoes continuous compression as a result of the spatially varying dispersion of the plasma. Our theoretical model, incorporating the detuning term and supported by particle-in-cell simulations, elucidates the compensation mechanism. It is shown that a chirped seed pulse with an initial bandwidth ~10% can be directly amplified by a factor of 1e7 to an intensity exceeding 1e17W/cm2 within a picosecond timescale in a steep density ramp. This scheme establishes a new foundation for advancing plasma-based light amplification toward practical applications.
