近日，湖北理工学院的王振来及其研究团队取得一项新进展。经过不懈努力，他们对旋转波结构光中的横向自旋和轨道角动量进行研究。相关研究成果已于2024年10月29日在国际知名学术期刊《物理评论A》上发表。

在单色光场中，该研究团队展示了携带与传播方向垂直的内禀横向轨道角动量的静止波涡旋所构成的旋转波结构化光。值得注意的是，研究人员发现这种旋转波结构化光揭示了横向自旋和轨道角动量密度的高度非平凡特性。

归一化的总角动量密度是普遍守恒的，这表明在自由空间中内禀横向自旋和轨道角动量之间存在相互转换。尽管在局部层面存在这种相互转换，但每个光子的涡旋拓扑电荷可以很好地定义积分内禀轨道角动量。

此外，横向自旋密度的方向由坡印廷动量密度的方向决定，体现了自由空间中的自旋-动量锁定效应。

附：英文原文

Title: Transverse spin and orbital angular momenta in rotating-wave structured light

Author: Zhen-Lai Wang

Issue&Volume: 2024/10/29

Abstract: Within monochromatic optical fields, we demonstrate rotating-wave structured light with a stationary wave vortex carrying intrinsic transverse orbital angular momentum orthogonal to the propagation direction of light. Remarkably, we find that such rotating-wave structured light reveals highly nontrivial features of transverse spin and orbital angular momentum densities. The normalized total angular momentum density is conserved universally, suggesting a mutual conversion of the intrinsic transverse spin and orbital angular momenta in free space. Despite such mutual conversion at the local level, integral intrinsic orbital angular momentum can be well defined with the topological charge of the vortex per photon. Moreover, the orientation of transverse spin density is governed by the direction of the Poynting momentum density, manifesting a spin-momentum-locking effect in free space.

DOI: 10.1103/PhysRevA.110.043523

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.043523