超强超短脉冲激光广泛应用于粒子加速以及新型X射线辐射源产生。较长的激光脉冲上升前沿直接影响激光应用效果。等离子体薄膜靶作为新型光学介质开关，可以有效降低超强激光脉冲前沿上升时间，优化激光等离子体相互作用参数。采用一维理论分析和粒子模拟方法研究了等离子体薄膜靶实现超强激光脉冲整形的机制。研究结果表明，薄膜靶通过对激光脉冲的非线性调制，可有效实现脉宽缩短和脉冲陡化；对比单层靶调制结果，选择参数优化的双层靶，可进一步优化脉冲整形效果，获得更短脉宽和更高振幅的激光脉冲；对于峰值振幅高于薄膜靶击穿阈值的超强激光，脉冲上升前沿可得到明显陡化，薄膜靶的击穿是产生这种脉冲整形效果的直接原因。

Powerful lasers are used to drive plasmas in next-generation particle accelerators and X-ray beams. One shortcoming of these beams is that they typically have a range of energy, caused by the gradual rise of laser power from zero to its maximum level. Using plasma foil as an optical switch, this rising time can be reduced effectively, delivering peak laser power to the plasma on a faster time scale. The method of laser-pulse shaping in the interaction of ultra-intense laser pulses with ultra-thin foils is studied by one-dimensional analytical theory and particle-in-cell simulation. Research results indicate that the pulse can be steepened and its width can be shortened effectively due to the self-consistent nonlinear modulation. In comparison to a single foil, a suitable double-foil scheme could optimize the shaping effect, and a transmitted pulse with both shorter duration and larger amplitude is obtained. When the peak amplitude of the incident pulse is higher than the smash threshold of the foil, the rising time of the shaped pulse could be shortened a lot, and the smash of the foil is the direct reason for this shaping effect.