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在啁啾脉冲放大飞秒激光系统中,为了获得近傅里叶变换极限的超短飞秒脉冲输出,需要对飞秒脉冲的光谱相位进行测量并消除未被补偿的残留啁啾。而光谱干涉仪因为其线性性、结构简单和灵敏度高等优点在飞秒脉冲光谱相位测量方面具有重要应用。介绍了基于交叉偏振波或自衍射效应的自参考光谱干涉技术,详细论述了该技术的工作原理。特别地以高斯光谱入射脉冲为例,对待测脉冲的光谱相位重构进行了详细的数值模拟,并指出基于交叉偏振波及自衍射效应的自参考光谱干涉技术对线性啁啾的测量范围。最后简单介绍利用光谱干涉仪和声光可编程色散滤波器相结合,用以消除飞秒激光脉冲中光谱相位残留啁啾的原理,实验中通过2次反馈迭代就获得了近傅里叶变换极限的飞秒脉冲输出。
In chirped pulse amplification femtosecond laser systems, in order to obtain ultra-short femtosecond pulse outputs with near-Fourier transform limits, the spectral phase of femtosecond pulses needs to be measured and the residual uncompensated chirp eliminated. Spectral interferometers have important applications in femtosecond pulse phase spectroscopy because of their linearity, simple structure and high sensitivity. The self-reference spectral interference technique based on cross-polarization or self-diffraction effect is introduced. The working principle of this technique is discussed in detail. Taking the incident pulse of Gaussian spectrum as an example, the spectral phase reconstruction of the pulse to be measured is numerically simulated. The linear chirp measurement range based on the self-reference spectral interference technique with cross-polarization and self-diffraction effect is also pointed out. Finally, the principle of using the spectral interferometer and the acoustooptic programmable dispersive filter to eliminate the residual chirp of the spectral phase in the femtosecond laser pulse is briefly introduced. In the experiment, the limit of the near Fourier transform is obtained by two feedback iterations Femtosecond pulse output.