离轴矢量光束的紧聚焦特性

Tightly Focusing Property of Off-axial Vector Beams

基于理查德-沃尔夫矢量衍射积分理论,数值研究了离轴矢量光束经过高数值孔径透镜后的紧聚焦特性.通过对比分析偏振奇点离轴的径向、角向矢量光束紧聚焦后,焦点附近的强度和相位分布规律,提出了一种由广义柱矢量光束设计紧聚焦场的方法.此外,通过分析矢量光束自旋分量的聚焦行为和自旋轨道耦合所诱导的自旋角动量分布变化,讨论了偏振奇点离轴对称破缺对高阶矢量光束紧聚焦场空间结构,特别是其自旋角动量空间分布的影响.该研究结果不仅对矢量光场的紧聚焦特性进行了补充,也为改进和完善焦场分布提供了理论参考.

The tightly focusing property of vector beams with off-axial polarization singularities are numerically investigated,according to the Richard-Wolf vector diffraction intergation theory.A method for designing speical focal field is proposed,based on the tightly focusing of vector field with generalized polarization distribution,after analyzing the tightly focusing of radially and azimuthally polarized beams.Moreover,the modulation effect of symmetric broken of off-axial polarization singularites on the focused field,especially the modulation effect on the Spin Angular Momentum(SAM)density,are discussed by analyzing the variation of SAM distributions arising from spin-orbital coupling.The results not only rich the tightly focusing property of vector beam,but also provide reference for improving the distribution of focal field.