紧聚焦的角向偏振艾里光束产生超分辨光针  

Super-resolution light needle achieved by tightly focusing azimuthally polarized airy beam

作　　者：刘嘉伟 聂仲泉 LIU Jiawei;NIE Zhongquan(Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030619, China;College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030619, China)

机构地区：[1]太原理工大学新型传感器与智能控制教育部与山西省重点实验室,太原030619 [2]太原理工大学物理与光电工程学院,太原030619

出　　处：《激光技术》2021年第3期390-395,共6页Laser Technology

基　　金：国家自然科学基金资助项目(11974258,11604236,61575139,11674239,51602213);山西省重点研发计划(高新领域)资助项目(201903D121127);山西省高等学校科技创新资助项目(2019L0151)。

摘　　要：为了研究角向偏振艾里光束的紧聚焦特性,采用理查德-沃夫矢量衍射理论分析优化了艾里光束的指数衰减因子、主环半径与比例因子对其入射光场分布的影响;分别研究了角向偏振艾里光束聚焦场分布与涡旋滤波器调制的角向偏振艾里光束的聚焦场分布,得到亚波长的角向中空场分布与亮场分布,实验结果与理论模拟基本一致。进一步利用粒子群算法设计多环涡旋相位滤波器调制角向偏振艾里光束,紧聚焦后得到了超长无衍射超分辨的横向偏振光针。结果表明,光针的半峰全宽为0.395λ,聚焦深度为37.432λ,纵横比达到94.788;通过计算斯托克斯参量分析聚焦光场的偏振分布,发现聚焦光场在径向偏振与角向偏振之间交替变化,且光束中心奇异点消失,实现了横向偏振的亮场分布。该研究在高密度的磁光存储、超分辨的光学成像、纳米光刻与粒子操作等领域具有广泛的应用。To study the tight focusing characteristics of azimuthally polarized Airy beams,the Richards-Wolf vector diffraction theory was adopt.The influences of the exponential attenuation factor,the radius of the main ring,and the proportional factor of the airy beams on the incident field patterns were respectively studied.The focal field distributions of the azimuthally polarized airy beams and the azimuthally polarized airy beams modulated by a vortex phase filter were studied,from which a sub-wavelength azimuthally polarized doughnut field and a transversally polarized bright field were garnered.The experimental results are basically consistent with the theoretical simulations.Furthermore,the multi-ring vortex phase filter was designed to modulate the azimuthally polarized airy beams according to the particle swarm algorithm,and an ultra-long and non-diffracting super-resolution transversally polarized light needle was produced on tight focusing.It turns out that the full width at half maximum and the depth of focus of the light needle are 0.395λand 37.432λrespectively,which corresponds to an aspect ratio of 94.788.The polarization patterns of the focal fields are analyzed by calculating the Stokes polarization parameters.It is found that the focal field alternates between the radial polarization and azimuthal polarization and the singularity at the center of the beam disappears,which testify that the transversally polarized bright field distribution is realized.The research holds broad applications in high-density magneto-optical storage,super-resolution optical imaging,nanolithography and particle manipulation.

关 键 词：物理光学 高密度磁光存储 矢量衍射理论 角向偏振光 斯托克斯分量 

分 类 号：O436.3[机械工程—光学工程]