用于超短脉冲扩展的时间望远镜

Time telescope for the expanding of ultrashort pulses

在理论上系统地研究了具有脉冲扩展功能的时间望远镜系统 ,时间望远镜主要是利用啁啾脉冲非线性参量转换过程实现的 ,它具有较高的转换效率和输出傅氏变换极限长脉冲的特点 .理论研究和数值模拟计算发现非线性晶体的群速度失配是造成时间像差和转换效率下降的主导因素 ,在此基础上提出了时间望远镜系统在设计中所应遵循的基本准则 ,在实验上成功地将 70fs光脉冲扩展成了近傅氏变换极限的 6 0ps长脉冲 .

In this paper we have theoretically investigated the time telescope that offers a function of pulse expanding. Time telescope, with features of high efficiency and near Fourier-transform limit, is constructed mainly by using nonlinear parametric conversions of chirped pulses. Based on both analytical and numerical studies, it is found that group-velocity mismatch of the nonlinear crystal plays an important role in temporal aberration and conversion efficiency, and the criteria for designing a near aberration-free telescope are summarized. Finally, it is experimentally demonstrated that a 70fs short pulse is expanded to a 60ps long pulse near Fourier-transform limit.