等离子体镜是提高超短脉冲激光信噪比的有效途径之一，在高温高密度等离子体产生、高能电子和离子的产生以及ICF和快点火等领域具有重要的应用。.本课题建立了描述等离子体镜开关特性的集居数-传输模型，理论研究了等离子体反射率与等离子体镜基片、入射激光强度、激光能量密度、激光脉冲宽度、偏振特性以及激光的入射角度之间的关系。利用脉冲宽度60fs和500fs的Ti：Sapphire激光系统，研究了不同偏振激光条件下等离子体镜的反射特性，实验结果表明s-偏振激光入射情况下，等离子体镜的反射率达到75%以上，而p-偏振激光入射情况下的反射率可达60%以上；等离子体镜最高反射率与脉冲宽度几乎无关，并且在高强度下反射率发生明显涨落；等离子体镜的信噪比在主脉冲1ps之前可达到2个数量级。理论模拟了级联双等离子体镜的特性，并且理论模拟表明等离子体镜具有一定的空间滤波特性。此外，还研究了等离子体镜反射率的上升时间和等离子体镜置于离焦位置时的反射率效果。.本课题的研究不仅对于深入认识等离子体镜提高超短脉冲激光的信噪比和反射率有益，而且研究结果还可应用于超短脉冲激光技术研究以及超短脉冲激光与等离子体相互作用研究。

Plasma mirror is one of the effective methods to improve the contrast ratio for ultrashort pulse laser, which is important in high temperature and high density plasmas research, generation of high energy electrons and ions, ICF and fast ignition, etc..In this project, a population-propagation model was derived based on the Maxwell equations and electron fluid equations of plasmas. The dependence of reflectivity of plasma mirror with substrate, laser intensity, laser fluence, pulse width, polarization and incidence angle was simulated with this model. The reflectivity of the plasma mirror was experimentally studied with a Ti:Sapphire laser system with the pulse width of 60 fs and 500 fs. The results showed that the reflectivity is over 75 % and 60 % with s- and p-polarized laser, respectively. The dependence of reflectivity with laser pulse width was measured, and the reflectivity was insensitive with the pulse width but fluctuates at higher intensities. The time-resolved contrast ratio was improved by two orders of manitude for the time delay bigger than 1 ps before the main pulse arrived. The reflectivity of cascaded double plasma mirrors was simulated, and simulation showed that the plasma mirror has a advantage for spatial filtering of the laser profile as well. In addition, the risetime of reflectivity was measured, and the reflectivity and its fluctuation was studied while the plasma mirror is placed on the off-focus positions..The results are helpful in understanding the characteristics of plasma mirror, and useful in ultrashort pulse laser research and laser-plasma interaction.

等离子体镜是提高超短脉冲激光信噪比的有效途径之一，在高温高密度等离子体产生、高能电子和离子的产生以及ICF和快点火等领域具有重要的应用。本课题建立了描述等离子体镜开关特性的集居数-传输模型，理论研究了等离子体反射率与等离子体镜基片、入射激光强度、激光能量密度、激光脉冲宽度、偏振特性以及激光的入射角度之间的关系。利用脉冲宽度60fs和500fs的Ti：Sapphire激光系统，研究了不同偏振激光条件下等离子体镜的反射特性，实验结果表明s-偏振激光入射情况下，等离子体镜的反射率达到75%以上，而p-偏振激光入射情况下的反射率可达60%以上；等离子体镜最高反射率与脉冲宽度几乎无关，并且在高强度下反射率发生明显涨落；等离子体镜的信噪比在主脉冲1ps之前可达到2个数量级。理论模拟了级联双等离子体镜的特性，并且理论模拟表明等离子体镜具有一定的空间滤波特性。此外，还研究了等离子体镜反射率的上升时间和等离子体镜置于离焦位置时的反射率效果。本课题的研究不仅对于深入认识等离子体镜提高超短脉冲激光的信噪比和反射率有益，而且研究结果还可应用于超短脉冲激光技术研究以及超短脉冲激光与等离子体相互作用研究。