The relativistic mirror (RM) is an interesting subject which introduced in the nonlinear regime of the laser–plasma interaction. Reflection of counter-propagating probe pulse from relativistic flying mirror has some excellent features, such as frequency up-shifting and compressing by a factor of 4γ2. In the high-intensity laser–plasma interaction, sometimes a sequence of RMs creates. For example, electron density cusps generate in the nonlinear laser wakefield generation or flying electron sheaths create in the blown-out regime of the laser foil interaction. Under these circumstances, the second counter-propagated seed (probe) pulse can be reflected back and forth between two or more successive RMs. This structure may be used as a relativistic cavity (RECA). Amplification and threshold conditions for the gain medium and pumping rate in the RECA are obtained, and it is shown that amplification can be started from background simultaneous emission (without seed pulse). A new feature of RECA is it's bidirectional (two frequencies) characteristic. Thereupon, the gain process can be implemented on the two different transitions in this bidirectional gain structure. In the RECA, driver pulse may be assembled as a pumping operation, and background plasma medium with high degree ionized substances is a good candidate for gain medium in the UV or X-ray regions. In this paper, we propose a new all-optical cavity for the generation of the ultrashort laser pulse in the UV or X-ray regions.

相对论镜（RM）是一个有趣的话题，它引入了激光与等离子体相互作用的非线性机制。从相对论飞行镜反向传播的探测脉冲的反射有一些优良的特性，诸如频率向上转换和由4倍压缩γ 2。在高强度激光-等离子体相互作用中，有时会形成一系列RM。例如，在非线性激光尾波场的产生中产生电子密度的尖峰，或者在激光箔相互作用的吹散状态中产生飞散的电子鞘。在这些情况下，第二个反向传播的种子（探测）脉冲可以在两个或多个连续的RM之间来回反射。该结构可用作相对论腔（RECA）。获得了RECA中增益介质和泵浦速率的放大率和阈值条件，结果表明可以从背景同时发射（无种子脉冲）开始放大。RECA的新功能是其双向（两个频率）特性。于是，可以在双向增益结构中的两个不同过渡上实现增益过程。在RECA中，驱动器脉冲可以作为泵浦操作进行组装，并且具有高度离子化物质的背景等离子体介质是UV或X射线区域中增益介质的理想选择。在本文中，我们提出了一种新的全光腔，用于在UV或X射线区域中产生超短激光脉冲。