Yan Bei, Qi Yingfeng, Wang Ziyao, Meng Yan, Yang Linyun, Zhu Zhen-Xiao, Chen Jing-Ming, Zhong Yuxin, Cheng Min-Qi, Xi Xiang, Gao Zhen
State Key Laboratory of Optical Fiber and Cable Manufacturing Technology, Southern University of Science and Technology, Shenzhen, China.
Department of Electronic and Electrical Engineering, Southern University of Science and Technology, Shenzhen, China.
Nat Commun. 2025 Jul 1;16(1):5659. doi: 10.1038/s41467-025-61238-7.
Recently, topological Dirac-vortex modes in Kekulé-distorted photonic lattices have attracted broad interest and exhibited promising applications in robust photonic devices such as topological cavities, lasers, and fibers. However, due to the vectorial nature of electromagnetic waves that results in complicated band dispersions and fails the tight-binding model predictions, it is challenging to construct three-dimensional (3D) topological photonic structures with Kekulé distortion, and the photonic topological Dirac-vortex modes have thus far been limited to two-dimensional (2D) systems. Here, by directly mapping a 3D Kekulé-distorted tight-binding model in a 3D tight-binding-like photonic crystal exhibiting scalar-wave-like band structures, we theoretically propose and experimentally demonstrate topological Dirac-vortex modes in a 3D photonic topological insulator for the first time. Using microwave near-field measurements, we directly observe robust photonic topological Dirac-vortex modes bound to and propagating along a one-dimensional (1D) Dirac-vortex line defect, matching well with the tight-binding and simulation results. Our work offers an ideal platform to map tight-binding models in 3D topological photonic crystals directly and opens a new avenue for exploiting topological lattice defects to manipulate light in 3D space.
最近，凯库勒扭曲光子晶格中的拓扑狄拉克涡旋模式引起了广泛关注，并在诸如拓扑腔、激光器和光纤等稳健光子器件中展现出了有前景的应用。然而，由于电磁波的矢量性质导致能带色散复杂且不符合紧束缚模型预测，构建具有凯库勒扭曲的三维（3D）拓扑光子结构具有挑战性，因此光子拓扑狄拉克涡旋模式目前仅限于二维（2D）系统。在此，通过直接在具有标量波状能带结构的类三维紧束缚光子晶体中映射三维凯库勒扭曲紧束缚模型，我们首次从理论上提出并通过实验证明了三维光子拓扑绝缘体中的拓扑狄拉克涡旋模式。利用微波近场测量，我们直接观测到了与一维（1D）狄拉克涡旋线缺陷绑定并沿其传播的稳健光子拓扑狄拉克涡旋模式，与紧束缚和模拟结果吻合良好。我们的工作提供了一个直接在三维拓扑光子晶体中映射紧束缚模型的理想平台，并为利用拓扑晶格缺陷在三维空间中操纵光开辟了一条新途径。
