径向偏振双曲正弦高斯光束深聚焦产生光链的研究

Study of 3D optical chain from a highly focused radially polarized sinh-Gaussian beam

基于Richards-Wolf的矢量衍射积分公式,研究了径向偏振双曲正弦高斯光束经过衍射光学元件(DOE)和高数值孔径(NA)透镜组成的光学系统后的聚焦特性,分析了相关参量对深聚焦特性的影响。研究表明,入射光束经过此光学系统后,在焦点附近产生沿光轴方向的三维多点光俘获结构——光链;改变相关参数,在焦平面附近产生一种针形光束—光渠。这些结果对于径向偏振双曲余弦高斯光束在粒子操控等方面的应用有着重要意义。

By using the Richards-Wolf vector dif fraction theory,the focusing properties of a radially polarized sinh-Gaussian b eam through a high numerical aperture （NA） with a diffra ctive optical element （DOE） are investigated in this paper.The phase of the incoming radially polarized sinh-Gaussian beam is spatially modulated by a diffractive optical element （DOE）.Numerical calculations are performed to analyze the influence of parameters on the tight focusing properties.Then the intensity distribution of radially polarized sinh- Gaussian beam after being focused by a high numerical aperture with a diffractive optical element （DOE） is studied.W e find that a three-dimensional optical chain along optical axis can be obtaine d near the focus by spatially modulating the phase of incoming beam,and the particles,whose refractive index is lower than t he ambient,could simultaneously be trapped by use of focused radially polarized sinh-Gaussian beams.Moreover,an optical needle can be generated by appropriately adjusting the correlated parameter of t he incident beam.The effects of correlated parameters of the incident b eam and the maximal angle of the high numerical-aperture objective are investigated.These properties may have quite important applicat ions in atom-optical experiment,such as optical trapping,material processing an d atom switches.