非均匀螺旋相位调制下对称破缺角向偏振光束的聚焦特性

Focusing Properties of Symmetric Broken Azimuthally Polarized Beams Modulated by Non-uniform Spiral Phases

提出了一种多参量调控角向偏振光束焦场强度和横向能流的方法.基于矢量衍射积分理论,数值模拟了非均匀螺旋相位和旋转对称振幅挡板调制下角向偏振光束的聚焦特性,讨论了螺旋相位结构和对称振幅挡板联合调制下,角向偏振光束焦场横向能流和偏振态的分布.结果表明:非均匀螺旋相位的引入改变了光场的聚焦特性,导致聚焦场重心产生了偏移;在偶数重旋转对称振幅挡板的联合调制下,焦场中出现了局部的椭圆偏振态和圆偏振态,且焦平面上出现了横向能流;通过调节螺旋相位,不仅可以实现焦场重心的特殊控制,还能进一步丰富焦场偏振态和横向能流分布.这种基于多参量调控焦场强度和能流分布的方法为实现操控特定区域的粒子提供了新的思路.

The controlling of the distributions of intensity and transversal energy flow in the focal filed of azimuthally polarized beams by multiple parameters was presented.The modulations of non-uniform spiral phase and rotationally symmetric amplitude obstacle on the focusing properties of azimuthally polarized beams were numerically studied,as well as their combined modulation on transversal energy flow and polarization distributions in the focal plane were also analyzed,based on the vectorial diffraction theory.The results demonstrate that the non-uniform spiral phase has significant effects on the focusing properties,and give rise to the shift of gravity of the focused field.With the combined modulation of evenfold rotationally symmetric amplitude obstacle,local elliptical polarization and circular polarization,as well as transversal energy flow appear in the focused field.Additionally,adjusting the phase structure not only can control the gravity of the focused field,but also can further enrich the focal field polarization state and transverse energy flow.This method of controlling the intensity and energy flow of focused field provides a new way to realize the manipulation of particles in special area.