Li Xing, Dan Dan, Yu Xianghua, Zhou Yuan, Zhang Yanan, Gao Wenyu, Li Manman, Xu Xiaohao, Yan Shaohui, Yao Baoli
State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China.
University of Chinese Academy of Sciences, Beijing 101408, China.
Nanophotonics. 2023 Nov 23;12(24):4507-4517. doi: 10.1515/nanoph-2023-0600. eCollection 2023 Dec.
Optical vortices (OVs), as eigenmodes of optical orbital angular momentum, have been widely used in particle micro-manipulation. Recently, perfect optical vortices (POVs), a subclass of OVs, are gaining increasing interest and becoming an indispensable tool in optical trapping due to their unique property of topological charge-independent vortex radius. Here, we expand the concept of POVs by proposing concentric ring optical traps (CROTs) and apply them to trapping and rotating particles. A CROT consists of a series of concentric rings, each being a vortex whose radius and topological charge can be controlled independently with respect to the other rings. Quantitative results show that the generated CROTs have weak sidelobes, good uniformity, and relatively high diffraction efficiency. In experiments, CROTs are observed to trap multiple dielectric particles simultaneously on different rings and rotate these particles with the direction and speed of rotation depending on the topological charge sign and value of each individual ring. In addition, gold particles are observed to be trapped and rotate in the dark region between two bright rings. As a novel tool, CROTs may find potential applications in fields like optical manipulation and microfluidic viscosity measurements.
光学涡旋（OVs）作为光学轨道角动量的本征模式，已被广泛应用于粒子微操纵。近来，完美光学涡旋（POVs）作为OVs的一个子类，因其独特的与拓扑电荷无关的涡旋半径特性，正受到越来越多的关注，并成为光学捕获中不可或缺的工具。在此，我们通过提出同心环光学陷阱（CROTs）来扩展POVs的概念，并将其应用于捕获和旋转粒子。一个CROT由一系列同心环组成，每个同心环都是一个涡旋，其半径和拓扑电荷可相对于其他环独立控制。定量结果表明，所产生的CROTs具有较弱的旁瓣、良好的均匀性和相对较高的衍射效率。在实验中，观察到CROTs能在不同环上同时捕获多个介电粒子，并根据每个环的拓扑电荷符号和值使这些粒子以不同的方向和速度旋转。此外，观察到金粒子在两个亮环之间的暗区被捕获并旋转。作为一种新型工具，CROTs可能在光学操纵和微流体粘度测量等领域找到潜在应用。
