Zhang Yu, Lin Qian, Zhuang Zikuan, Lin Fei, Hong Ling, Che Zhen, Zhuo Linqing, Li Yongyao, Zhang Li, Zhao Dongxu
Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, Guangdong 528225, China.
School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528225, China.
Nanophotonics. 2025 Jan 24;14(6):833-843. doi: 10.1515/nanoph-2024-0586. eCollection 2025 Apr.
Spin-orbit coupling (SOC) in tightly focused optical fields offers a powerful mechanism for manipulating the complex motion of particles. However, to date, such a mechanism has only been applied to the single-orbit motion for particles, while multi-orbital dynamics have not yet been experimentally demonstrated. Here, the theoretical and experimental realization of dual-orbit rotational dynamics of nanoparticles in a tightly focused circularly polarized Laguerre-Gaussian beam is reported. Analyses reveal that the dual-orbit rotation of nanoparticles originates from SOC in a tightly focused vortex beam, with the motion velocity and direction determined by the topological charge of the beam. Experimentally, the dual-orbit rotation of polystyrene nanoparticles was observed for the first time using an inverted optical tweezer. In addition, the rotation velocity showed a clear linear dependence on the topological charge of the incident beam. This work reveals the pivotal role of SOC in enabling precise dual-orbit control at the nanoscale, paving the way for applications in optical sorting, grinding and delivery of microparticles.
在强聚焦光场中的自旋轨道耦合（SOC）为操纵粒子的复杂运动提供了一种强大的机制。然而，迄今为止，这种机制仅应用于粒子的单轨道运动，而多轨道动力学尚未得到实验证明。在此，报道了在强聚焦圆偏振拉盖尔 - 高斯光束中纳米粒子双轨道旋转动力学的理论和实验实现。分析表明，纳米粒子的双轨道旋转源于强聚焦涡旋光束中的SOC，其运动速度和方向由光束的拓扑电荷决定。在实验中，首次使用倒置光学镊子观察到了聚苯乙烯纳米粒子的双轨道旋转。此外，旋转速度与入射光束的拓扑电荷呈现出明显的线性依赖关系。这项工作揭示了SOC在实现纳米尺度精确双轨道控制方面的关键作用，为微粒的光学分选、研磨和输送等应用铺平了道路。
