Dynamics of dual-orbit rotations of nanoparticles induced by spin–orbit coupling

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 d...

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Bibliographic Details
Main Authors: Zhang Yu, Lin Qian, Zhuang Zikuan, Lin Fei, Hong Ling, Che Zhen, Zhuo Linqing, Li Yongyao, Zhang Li, Zhao Dongxu
Format: Article
Language:English
Published: De Gruyter 2025-01-01
Series:Nanophotonics
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Online Access:https://doi.org/10.1515/nanoph-2024-0586
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Summary: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.
ISSN:2192-8614