高阶拉盖尔-高斯径向偏振光束强聚焦产生的光链

Optical chain generated by tight focusing of radially polarized higher-order Laguerre-Gaussian beams

基于Richards-Wolf的矢量衍射积分公式,研究了高阶拉盖尔-高斯径向偏振光束经过衍射光学元件(DOE,diffractive optical elements)和高数值孔径(NA)透镜组成的光学系统后的聚焦特性。根据数值模拟结果,比较了相关参量的变化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,并且入射光束的相关参数和聚焦透镜的NA大小都会影响光束的聚焦特性。

By using the Richards-Wolf vector diffraction theory, the focusing properties of higher-order Laguerre-Gaussian laser beams through a high numerical aperture with a diffractive optical element （DOE） are investigated in this paper. The phase of the incoming higher-order Laguerre-Gaussian laser is spatially modulated by a diffractive optical element （DOE）. Numerical calculations are performed to compare the influence of parameters on the tight focusing properties. The intensity distribution of higherorder Laguerre-Gaussian laser after being focused by a high numerical aperture with a DOE is simulated. It is shown that a three-dimensional optical chain along optical axis can be obtained near the focus by spatially modulating the phase of incoming beam,and the particles whose refractive index is lower than that of the ambient could simultaneously be trapped by use of focused higher-order Laguerre-Gaussian laser beams. The effects of correlated parameters of the incident beam and the maximal angle of the high numerical-aperture objective are investigated in detail. Moreover, by adjusting relative parameters, the shape of the focus spot can be controlled,and the focus spot can trap different particles by changing the corresponding parameters. These results are quite important for many potential applications, such as optical trapping,optical data storage,particle acceleration,and particle transport.