基于两种非共线相位匹配几何构型的类腔式多程OPCPA结构及其放大性能研究

800nm宽带光参量啁啾脉冲放大（OPCPA）的量子过程决定了其~66%的泵浦-信号理论转换效率极限。受限于时空逆转换效应，实际泵浦-信号转换效率远低于此，从而极大限制了基于OPCPA技术的拍瓦级超强超短激光装置的输出能力。本项目围绕基于两种非共线相位匹配几何构型的类腔式多程OPCPA结构及其放大性能开展研究，旨在利用该结构具有不断释放由OPCPA过程所产生的闲频光的特点，实现对时空逆转换效应的有效抑制，解决OPCPA放大器的增益带宽和泵浦-信号转换效率难以同时提升的关键科学问题。前期的理论研究表明：该结构不仅可以提升OPCPA的泵浦-信号转换效率至接近理论极限，还可以同时改善信号光的光束质量以及输出能量稳定性等。因此，本项目研究有望突破基于传统单程结构OPCPA技术固有的较低泵浦-信号转换效率的技术瓶颈，为基于OPCPA技术的百拍瓦级超强超短激光装置主放大器的研制提供更为可靠的技术途径。

The quantum process of optical parametric chirped pulse amplification (OPCPA) at 800nm broadband decides the pump-to-signal conversion efficiency theoretical-limit of ~66%. Limited to the spatial and temporal back-conversion effect, the actual pump-to-signal conversion efficiency of OPCPA is far from the theoretical-limit, which dramatically limits the output ability of pettawatt ultra-intense ultra-short laser facility based on OPCPA technique. The project does the research on the amplification performance of the cavity-like multi-pass OPCPA structure based on the two non-collinear phase matching geometry configurations, aiming to realize the efficient inhibition on the spatial and temporal back-conversion effect via utilizing the structure feature of releasing the idler produced in the OPCPA process, and solve the key scientific difficulty that the gain bandwidth and the pump-to-signal conversion efficiency cannot be improved simultaneously. The previous theoretical research demonstrated that the structure can not only increase the pump-to-signal conversion efficiency to approach the theoretical-limit, but also improve the beam quality of signal and the stability of output energy, and etc. Thus, the research of project is believed to break through the technical bottleneck of the inherent low pump-to-signal conversion efficiency of OPCPA based on the traditional single-pass structure, and provide a more reliable technical approach for the development of the main amplifier in ultra-intense ultra-short lasers facility at hundreds of petawatt level based on OPCPA technique.