In this paper, the generation of relativistic electron mirrors (REMs) and the reflection of an ultra-short laser off this mirrors are discussed, applying two-dimensional particle-in-cell (2D-PIC) simulations. REMs with ultra-high acceleration and expanding velocity can be produced from a solid nanofoil illuminated normally by an ultra-intense femtosecond laser pulse with a sharp rising edge. Chirped attosecond pulse can be produced through the reflection of a counter-propagating probe laser off the accelerating REM. In the electron moving frame, the plasma frequency of the REM keeps decreasing due to its rapidly expanding. The laser frequency, on the contrary, keeps increasing due to the acceleration of REM and the relativistic Doppler shift from the lab frame to the electron moving frame. Within an ultra-short time interval, the two frequencies will be equal in the electron moving frame, which leads the resonance between laser and REM. The reflected radiation near this interval and the corresponding spectra will be amplified due to the resonance. Through adjusting the arriving time of the probe laser, certain part of the reflected field could be selectively amplified or depressed, leading to the selectively adjusting of the corresponding spectra.

在本文中，讨论了相对论电子镜（REMs）的产生以及超短激光在该镜上的反射，并应用了二维单元格内粒子（2D-PIC）模拟。固态纳米箔可以通过具有强烈上升沿的超强飞秒激光脉冲正常照射，从而产生具有超高加速度和膨胀速度的REM。counter声的阿秒脉冲可以通过反向传播的探针激光反射离开加速的REM来产生。在电子移动框架中，REM的等离子体频率由于其迅速扩展而不断降低。相反，由于REM的加速和相对论多普勒从实验框架向电子移动框架的移动，激光频率一直在增加。在极短的时间内 在电子移动框架中，这两个频率将相等，这将导致激光和REM之间的共振。由于共振，该间隔附近的反射辐射和相应的光谱将被放大。通过调整探测激光器的到达时间，可以选择性地放大或抑制反射场的某些部分，从而有选择地调整相应的光谱。