光束夹角及空间分布对光克尔开关门成像的影响

Influence of Beam Angle and Spatial Distribution on Optical Kerr Gate Imaging

构建光克尔效应时间门物理模型,采用抽运探测实验获得的二硫化碳(CS2)克尔信号曲线作为光开关门响应函数,对光束传输进行时间切片和空间离散,模拟出了光开关门的时空演化规律。研究了在不同的抽运光与探测光夹角和光束空间分布情况下的时间门宽度和光束强度分布。结果表明:对于高斯空间分布的抽运光束和探测光束,随着抽运光束与探测光束夹角增大,时间门变窄,光斑由对称圆变成椭圆形,交叉角越大,椭圆度越大;如果抽运光束和探测光束的空间分布为超高斯分布,随着光束夹角增大,开关门的时间曲线前沿不断变缓,但光斑空间形状基本没有变化,椭圆光斑的椭圆度约为1/3。这些结果为抽运探测和光学弹道成像等实验参数的选取提供了一定的参考依据。

A model of optical Kerr effect time gate is built.The CS2 Kerr signal curve obtained through the pumpprobe experiment is acted as optical gate response function.The beam propagation is divided through time slicing and space distribution,and the temporal and spatial variation of the optical gate is given through the simulation.The width of the time gate and the spatial distribution of the beam are studied under different angles between the pump beam and the probe beam and different spatial distributions of the pulses.The results indicate that,for the pump beam and probe beam with Gaussian distribution,the time gate width becomes narrow with the intersection angle increasing between the pump beam and the probe beam,and the spatial distribution changes from roundness to ellipse.The bigger the intersection angle is,the bigger the ellipse degree is.If the spatial distributions of input pump beam and probe beam are super-Gaussian distribution,the rise edge of the temporal distribution becomes slow with increasing intersection angle between the pump beam and the probe beam,while the spatial distribution is unchanged,and the ellipse degree is about 1/3.The results provide reference for parameter design of experiments such as pump probe and time gated ballistic imaging.