The Temporal Diffraction Characteristic of A Femtosecond Laser Pulse by A Serrated Aperture

Based on Fresnel diffraction theory we give out the light field distribution for the definite frequency component of a femtosecond laser pulse when the laser pulse passes through a serrated aperture. Through an inverse Fourier transformation, we get the temporal diffraction field function of the femtosecond laser pulse at any distance. The temporal diffraction field function is related to the width of the laser pulse, the structure of the serrated aperture, the Fresnel number at central frequency and time. Number calculation shows when the width of the laser pulse is within a few tens of femtoseconds and Fresnel number at central frequency is much, the temporal diffraction intensity is not a Gaussian distribution. Nevertheless when Fresnel number at central frequency is less than ten, the temporal diffraction intensity can be approximately regarded as a Gaussian distribution and has a time delay effect.