Shi Peng, Du Luping, Li Congcong, Zayats Anatoly V, Yuan Xiaocong
Nanophotonics Research Center, Shenzhen Key Laboratory of Micro-Scale Optical Information Technology & Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
Nanophotonics Research Center, Shenzhen Key Laboratory of Micro-Scale Optical Information Technology & Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China;
Proc Natl Acad Sci U S A. 2021 Feb 9;118(6). doi: 10.1073/pnas.2018816118.
Spin-momentum locking, a manifestation of topological properties that governs the behavior of surface states, was studied intensively in condensed-matter physics and optics, resulting in the discovery of topological insulators and related effects and their photonic counterparts. In addition to spin, optical waves may have complex structure of vector fields associated with orbital angular momentum or nonuniform intensity variations. Here, we derive a set of spin-momentum equations which describes the relationship between the spin and orbital properties of arbitrary complex electromagnetic guided modes. The predicted photonic spin dynamics is experimentally verified with four kinds of nondiffracting surface structured waves. In contrast to the one-dimensional uniform spin of a guided plane wave, a two-dimensional chiral spin swirl is observed for structured guided modes. The proposed framework opens up opportunities for designing the spin structure and topological properties of electromagnetic waves with practical importance in spin optics, topological photonics, metrology and quantum technologies and may be used to extend the spin-dynamics concepts to fluid, acoustic, and gravitational waves.
自旋动量锁定是一种拓扑性质的表现，它支配着表面态的行为，在凝聚态物理和光学领域得到了深入研究，从而发现了拓扑绝缘体及相关效应以及它们的光子对应物。除了自旋外，光波可能具有与轨道角动量或非均匀强度变化相关的复杂矢量场结构。在此，我们推导了一组自旋动量方程，该方程描述了任意复电磁导模的自旋与轨道特性之间的关系。所预测的光子自旋动力学通过四种非衍射表面结构波进行了实验验证。与导行平面波的一维均匀自旋不同，对于结构化导模观察到了二维手性自旋涡旋。所提出的框架为设计在自旋光学、拓扑光子学、计量学和量子技术中具有实际重要性的电磁波的自旋结构和拓扑性质开辟了机会，并且可用于将自旋动力学概念扩展到流体波、声波和引力波。
