π相位板产生矢量光束的高数值孔径聚焦特性研究

Study on High-Numerical-Aperture-Focused Characteristics of Vector Beam Produced by π Phase Plate

借助马赫曾德尔干涉仪光路,用简单的π相位板把线偏振光转换为径向和角向矢量空心光束,应用RichardsWolf经典矢量衍射模型,计算了高数值孔径透镜聚焦条件下光波电磁场的分布,结果表明:用10-3 W量级的激光功率照明,产生轴对称矢量空心光束的最大光强达到1011 W·m-2量级,最大光强梯度达到1017 W·m-3量级,暗斑半径仅有0.24λ,同时出现了很强的纵向电场和磁场分布;调节干涉仪光路的光程差可调节局域光子轨道角动量密度的分布,这种光束在原子光学中有很好的应用前景。

Linear polarized light is converted to radial and angular vector hollow beams by using Mach-Zehnder interferometer light path with n phase plate. The distribution of the electromagnetic field focused with high numerical aperture is calculated by employing the Richards-Wolf classical vector diffraction model. The results show that the maximum intensity and intensity gradient of the axisymmetric vector hollow beam can respectively reach the magnitude of 10^11 ·m^-2 and 10^17 W·m^-3 under the illumination of laser with the power of 10 3 W magnitude, and the radius of the dark spot is only 0.24λ. Meanwhile, strong distributions of the longitudinal electric and magnetic fields are produced. The density distribution of the local photon orbital angular momentum can be adjusted by regulating the optical path difference of the interferometer. Therefore, this beam has good application prospect in atomic optics.