Topological Spin States in 3D Coupled Electromagnetic Fields

作者：Liang Fang, Yuanjiang Xiang, Qinjun Chen, Shuangchun Wen · 发表于：Physical Review Letters · 年份：2025 · DOI：10.1103/physrevlett.134.013801 · 被引用次数：11 · 研究领域：Topological Materials and Phenomena、Orbital Angular Momentum in Optics、Metamaterials and Metasurfaces Applications

Topological defects are nonsmooth field configurations with singularities that widely exist in physics and multidisciplinary areas. Here, we introduce near-field polarization evolution and the resulting topological spin states in a system of silicon-based coupled waveguides. The topological spin structures originate from 3D evanescent field coupling that transforms the trivial transverse spin into the topological spin states in a 2D plane. Moreover, we show that the periodic coupling of higher-order electromagnetic modes can produce intriguing spin defect (singularity) arrays, including those with alternately topological charges of ±1. These findings may further expand the family of electromagnetic topological structures, and open new avenues to engineer photon emission and light-matter interactions on integrated photonic platforms.