基于受激布里渊散射与激光诱导击穿组合压缩的大能量皮秒激光产生研究

With high energy efficiency and phase conjugation, pulse compression by stimulated Brillouin scattering (SBS) is a promising way to generate ultrashort pulses with high energy. In the process of SBS compression, only the leading edge of the Stokes pulse is amplified and minimum output duration is limited by the phonon lifetime in an order of sub-nanosecond. This project application proposes a laser pulse temporal compression technique combining SBS and laser-induced breakdown in which the leading edge of the laser pulse is compressed using SBS and the low intensity tailing edge of the laser pulse is truncated by LIB. Firstly, we will construct a theoretical model to inquire the optimum experiment parameters; Next, an interferometric scheme is studied to promote the performance of SBS compression; Finally, nanometer materials are dopped into LIB active medium to decrease the LIB threshold and suppress other nonlinear effect compretition. Expected results will be considerable interest in the application to long distance laser detection, picosecond laser processing and nonlinear spectroscopy.

受激布里渊散射脉宽压缩具有高能量转化效率、相位共轭等特点，是一种非常有应用前景的大能量短脉冲产生技术。现行的受激布里渊散射压缩器受限于介质声子寿命，无法实现超短脉冲输出。本项目旨在将基于脉冲前沿压缩的受激布里渊散射与基于脉冲后沿压缩的激光诱导等离子体开关结合，利用两者原理上的互补探索一种高效率实现大能量皮秒脉冲的新方法。拟通过受激布里渊散射先将大能量长脉冲压缩成亚纳秒陡前沿脉冲，再将陡前沿脉冲通过等离子体开关进行后沿压缩，从而实现皮秒脉冲输出。为此，将先建立组合压缩模型研究该方案产生皮秒脉冲的具体条件；其次，通过驻波驱动受激布里渊散射加强声波场与光波场耦合，进一步提升受激布里渊散射级的压缩能力；最后，向击穿介质中掺杂纳米颗粒，用以降低击穿阈值、抑制其他非线性效应，从而提高能量转化效率。预期成果将在远距离激光探测、皮秒激光加工、非线性光学光谱分析等领域发挥重要作用。

高能短脉冲激光是物理学、化学、生物学等基础学科研究的重要工具，也是激光光谱学等学科对微观世界进行研究和揭示新的超快过程的重要手段。基于受激布里渊散射脉宽压缩效应产生大能量短脉冲激光是一条有效的技术途径。但在传统压缩机制下，SBS脉宽压缩技术仅能对泵浦脉宽前沿压缩，产生亚纳秒级激光，很大程度上限制了该项技术的应用。因此本项目提出了一种压缩前沿的SBS与压缩后沿的激光诱导击穿结合的方案，一方面通过结构优化最大程度上发掘SBS压缩的潜能，获得了亚声子寿命的输出，另一方面对SBS压缩后的脉冲进行后沿压缩，最终实现了高能量的皮秒激光输出，开拓了一种产生高能皮秒激光的技术方案。