Bai Yihua, Dong Miao, Zhang Mingyan, Yang Yuanjie
School of Physics, University of Electronic Science and Technology of China, Chengdu, 610054, China.
Nanoscale Res Lett. 2019 Jul 26;14(1):252. doi: 10.1186/s11671-019-3089-5.
The characteristics of a circularly polarized anomalous vortex beam (CPAVB), focused by an objective lens with a high numerical aperture (NA), are studied analytically and theoretically. It shows that the topological charge can affect the beam profile significantly and a flat-topped (FT) beam can be obtained by modulating the NA and topological charge. It is interesting to find that spin-to-orbital angular momentum conversion can occur in the longitudinal component after tight focusing. Furthermore, optical forces of the tightly focused CPAVB on nanoparticles are analyzed in detail. It can be expected to trap two kinds of nanoparticles using such beam near the focus.
研究了具有高数值孔径（NA）的物镜聚焦的圆偏振异常涡旋光束（CPAVB）的特性。分析表明，拓扑电荷会显著影响光束轮廓，通过调制数值孔径和拓扑电荷可以获得平顶（FT）光束。有趣的是，发现在紧聚焦后纵向分量中会发生自旋到轨道角动量的转换。此外，详细分析了紧聚焦CPAVB对纳米粒子的光学力。可以预期使用这种光束在焦点附近捕获两种纳米粒子。
