光参量啁啾脉冲饱和放大的增益稳定性

 光参量啁啾脉冲放大（OPCPA）在饱和放大区存在一个增益稳定点，据此设计了一个输出稳定的三级OPCPA系统；第一、二、三级分别选用准相位匹配的周期极化钛氧磷酸钾（PPKTP）晶体、LBO晶体和KDP晶体作为增益介质。饱和放大时，增益随泵浦光强度变化时的增益输出稳定性明显改善，在泵浦光强度抖动低于6%的情况下，各级光参量放大器OPA输出的增益抖动小于1%。前级采用准相位匹配的PPKTP晶体作为增益介质，在远低于破坏阈值的30MW/cm²的泵浦功率密度下，可得到2×10⁵的饱和放大增益和20%的能量转换效率。

Gain stability of saturation amplificated in optical parametric chirped-pulse amplification system

A laser system with high output stability was designed for three-stage optical parametric chirped-pulse amplification(OPCPA). The PPKTP crystal was chosed as the first-stage gain medium, the LBO and the KDP crystal were used for the second-stage and third-stage, respectively. Through numerical simulations, the output gain and gain stability were obtained for three stage optical parametric chirped pulse saturated amplification. In the case of pumping intensity jitter less than 6%, the output gain jitter of the OPCPA system is less than 1%. In the case of PPKTP crystal chosed as the first-stage quasi-phase matching gain medium, with a pump peak intensity of 30MW/cm~2, which is far from damaging the PPKTP crystal, the saturation amplificated gain is 2×10~5 and the conversion efficiency is 20%.