飞秒激光啁啾的直观可行检测方法

Feasible and intuitive measuring method for femtosecond laser pulses chirp

基于飞秒脉冲相关干涉项含有脉冲的相位和频率信息,测量自相关二次谐波干涉条纹可见的振荡频率为ωτ及2ωτ两个谱分量的大小和形状,以及二次干涉自相关函数包络面积的大小和形状,可以得到飞秒激光脉冲啁啾大小的信息。另外,通过对二次干涉自相关(IAC)迹线求一阶导数得到的干涉自相关导数光谱(D-MOSAIC)的峰谷与啁啾正负对应关系,找到了判定啁啾正负的方向因子即正弦函数因子,据此能够判断飞秒激光脉冲啁啾的正负。因此,采用能够满足光学相干探测基本条件的测量系统,利用二阶干涉自相关法可以用来检测飞秒脉冲激光的啁啾特性。

Based on the fact that interferometric correlation term of femtosecond pulse contains the phase and frequency information,the magnitude information of chirp of femtosecond laser pulse can be obtained by measuring the magnitude and shape of two visual spectra component with surging frequency ωτ and 2ωτ inside the autocorrelation second harmony interferometric stripe,and the area and shape of envelope of second interferometric autocorrelation function.Otherwise,through the derivative modified spectrum of autointerferometric correlation（D-MOSAIC） derived from a conventional second order interferometric autocorrelation trace,whose peak and value correspond to the positive and negative chirp,the sine function factor of the determinant chirp direction was obtained.Futhermore,chirp direction of ultrashort laser pulses could be determined.Thus,the chirp characteristics of femtosecond pulse laser could be detected through second order autointerferometric correlation using measurement system meeting basic condition of optics interference.