Xu Xiaohao, Nieto-Vesperinas Manuel, Zhou Yuan, Zhang Yanan, Li Manman, Rodríguez-Fortuño Francisco J, 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, 100049, China.
Nat Commun. 2024 Jul 24;15(1):6230. doi: 10.1038/s41467-024-50440-8.
Optical forces and torques offer the route towards full degree-of-freedom manipulation of matter. Exploiting structured light has led to the discovery of gradient and curl forces, and nontrivial optomechanical manifestations, such as negative and lateral optical forces. Here, we uncover the existence of two fundamental torque components, which originate from the reactive helicity gradient and momentum curl of light, and which represent the rotational analogues to the gradient and curl forces, respectively. Based on the two components, we introduce and demonstrate the concept of lateral optical torques, which act transversely to the spin of illumination. The orbital angular momentum of vortex beams is shown to couple to the curl torque, promising a path to extreme torque enhancement or achieving negative optical torques. These results highlight the intersection between the areas of structured light, Mie-tronics and rotational optomechanics, even inspiring new paths of manipulation in acoustics and hydrodynamics.
光力和光扭矩为实现物质的全自由度操控提供了途径。利用结构化光已促成了梯度力和旋度力以及诸如负向和横向光力等非平凡光机械表现形式的发现。在此，我们揭示了两种基本扭矩分量的存在，它们分别源自光的反应性螺旋度梯度和动量旋度，并且分别代表梯度力和旋度力的旋转类似物。基于这两个分量，我们引入并演示了横向光扭矩的概念，其作用方向与照明的自旋方向垂直。涡旋光束的轨道角动量被证明与旋度扭矩耦合，有望实现极端扭矩增强或实现负向光扭矩。这些结果突出了结构化光、米氏光学和旋转光机械学领域之间的交叉点，甚至为声学和流体动力学中的新操控路径提供了灵感。
