近日，香港科技大学Chan, C. T.团队研究了无绝缘体拓扑光子多车道高速公路。2026年7月22日，《自然》杂志发表了这一成果。

光子结构中的拓扑保护能够实现不受结构无序影响的鲁棒单向传播。然而，传统实现方案中这种保护源于拓扑绝缘体区域，其界面容纳有狭窄的导波通道，使得大部分绝缘体体区域对输运无贡献。这带来了拓扑鲁棒性与空间占用之间的根本性权衡。

研究组引入一种无绝缘体的拓扑波导架构，消除了这种权衡，可实现兼具100%空间利用效率和拓扑保护的多车道单向光导引。通过策略性地将旋磁蜂窝光子晶体中的时间反演对称破缺与反演对称破缺相结合，研究组在平庸绝缘相和陈绝缘体相之间的不同临界转变边界处，实现了四种不等价的光子谷半半金属。

研究组将这四种结构以平行循环的方式排列，使得每个区域同时充当谷选择波导，并作为相邻区域中另一个谷的拓扑势垒，从而无需额外的拓扑绝缘层。该实验和理论结果表明，这种多车道配置将常规的边界态转变为密集排列的大面积单向模式。这些模式在四个区域中表现出交替的单向性，同时在任意尖锐弯折和显著形状变化下仍保持鲁棒性。这项工作展示了一种超紧凑拓扑光子电路的设计策略，有望应用于高密度集成光学。

附：英文原文

Title: Insulator-free topological photonic multi-lane highways

Author: Cui, Xiaohan, Zhang, Ruo-Yang, Wang, Mudi, Gao, Zi-Xuan, Chen, Xiao-Dong, Zhang, Zhao-Qing, Lai, Yun, Chan, C. T.

Issue&Volume: 2026-07-22

Abstract: Topological protection in photonic structures enables robust unidirectional propagation immune to structural disorder1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20. However, conventional implementations obtain this protection from topological-insulator domains whose interfaces host narrow guiding channels, leaving much of the insulating bulk inactive for transport. This imposes a fundamental trade-off between topological robustness and spatial footprint21,22,23,24,25. Here we introduce an insulator-free topological waveguide architecture that eliminates this trade-off, enabling multi-lane unidirectional light guiding with both 100% spatial utilization efficiency and topological protection. By strategically combining time-reversal and inversion-symmetry breaking in gyromagnetic honeycomb photonic crystals (PCs), we achieve four inequivalent photonic valley half-semimetals (PVHSMs)26,27 at distinct critical transition boundaries between trivial and Chern insulator phases. We arrange these four structures in a parallel, cyclic configuration, such that each domain simultaneously functions as a valley-selective waveguide and a topological barrier for the other valley in adjacent domains, circumventing the need for further topological insulating layers. Our experimental and theoretical results demonstrate that this multi-lane configuration transforms conventional edge states into densely packed, large-area one-way modes. These modes exhibit alternating unidirectionality across the four domains while maintaining robustness even under arbitrary sharp bends and pronounced shape variations. This work exemplifies a design strategy for ultracompact topological photonic circuits, with potential for high-density integrated optics.

DOI: 10.1038/s41586-026-10817-9

Source: https://www.nature.com/articles/s41586-026-10817-9