摘要
对于光学涡旋特别是具有复杂拓扑结构的光学涡旋,可以通过数值计算的方法获得实验上难以准确测量的角动量分布及其传输演化特性。在略去线偏振光场线动量密度中的轴向分量的情况下可获得涡旋光场的横向线动量密度,其在光束截面上的角向分量表征了涡旋角动量的分布。通过数值模拟,研究了单束拉盖尔-高斯光束和拓扑荷不同的两束拉盖尔-高斯光束同轴叠加后在自由空间中的传播过程,获得了强度分布、相位分布和横向线动量密度在瑞利长度内的分布特征。通过分析光束横截面上强度分布和线动量密度的演化特性表明,在远离束腰处光束的衍射效应不仅降低了横向线动量密度,还会增加径向分量,因而增强了径向力学特性,减弱了角向力学特性,因此在具体实施微操控时不宜在距离束腰面较远的横截面内进行。
The angular momentum distributions and their propagation evaluation characteristics of optical vortices,especially vortices with the complicated topological structure,which are difficult to measure accurately through an experiment,can be obtained by numerical computation.The lateral linear momentum density of optical vortices is obtainable by neglecting the longitudinal component of linear momentum density of linearly polarized optical field,and the angular momentum distribution is characterized by the azimuth component of lateral linear momentum density.The propagations of a single Laguerre-Gaussian beam and a vortex beam superimposed by two Laguerre-Gaussian beams with different topological charges are numerically simulated in free space.Through the simulation,the transverse profiles of intensities,phases,and lateral linear momentum density in Rayleigh range are obtained.It is shown that the lateral linear momentum density is reduced,and that simultaneously the radial component of linear momentum is increased due to the beam diffraction.Consequencely,the radial mechanics is enhanced and the azimuth one is abated.Therefore,the beam cross sections which are far away from the beam waist are not suitable to be utlized for the manipulation of microparticles.
出处
《光学学报》
EI
CAS
CSCD
北大核心
2010年第11期3323-3327,共5页
Acta Optica Sinica
基金
瞬态光学与光子技术国家重点实验室开放基金(SKLST200911)
西北工业大学基础研究基金资助课题
关键词
物理光学
光学涡旋
横向线动量密度
角动量
拉盖尔-高斯光束
physical optics
optical vortex
lateral linear momentum density
angular momentum
Laguerre-Gaussian（LG） beam
