用SPIDER法重构飞秒脉冲位相中参数的选择

Optimization of parameters on reconstruction of phase of femtosecond laser pulse with SPIDER

为了更精确地测量飞秒脉冲特性以满足其不断拓宽的应用,基于光谱相位相干直接电场重构法(SP IDER)测量飞秒激光脉冲的基本原理和重构相位的反演算法,数值模拟了SP IDER重构飞秒脉冲相位的过程,分析了时间延迟τ、光谱剪切量Ω及滤波窗口宽度的选取原则。以宽度约为20 fs的高斯型线性啁啾脉冲为例,通过选取不同的时间延迟τ和光谱剪切量Ω重构脉冲的相位,发现重构位相曲线与原输入脉冲位相曲线最接近时,时间延迟τ约为1 210 fs,相对光谱剪切量Ω/Δω约为9%,滤波窗口宽度约为τ/3。

To meet the ever increasing applications of femtosecond laser pulse, it has to be measured more precisely. Based on the spectral phase interferometry of direct electric-field reconstruction （SPIDER）, the spectral phase of femotosecond laser pulse was reconstructed with numerical simulations. The crucial parameters that include the time delay r between the tested pulse replicas, the frequency shear Ω and the width of filter window were analyzed to choose their values properly. With the Gauss linearly chirped pulse whose full width at half maximum （FWHM） is about 20 fs, the phase is reconstructed with different time delay and different frequency shear Ω/△ω. The optimum phase curve is about at τ=1210 fs and relative shear is Ω/△ω=0.09. The width of filtering window is about τ/3.