Second‐order topological insulators can be characterized by their bulk polarization, which is believed to be intrinsically connected to the center of the Wannier function. In this study, the existence of second‐order topological insulators is demonstrated that feature a pair of partially degenerate photonic bands. These arise from the nonsymmorphic glide symmetry in an all‐dielectric photonic crystal. The center of the maximally localized Wannier function (MLWF) is consistently located at the origin but is not equivalent with respect to the sum of constituent polarizations. As a result, topological corner modes can be identified by the distinctly hybridized MLWFs that truncate at the sample boundary. Through full‐wave numerical simulations paired with microwave experiments, the second‐order topology is clearly confirmed and characterized. These topological corner states exhibit notably unique modal symmetries, which are made possible by the inversion of the Wannier bands. These results provide an alternative approach to explore higher‐order topological physics with significant potential for applications in integrated and quantum photonics.

中文翻译：

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滑移对称光子晶体中复合万尼尔态的拓扑角模式

二阶拓扑绝缘体可以通过其体极化来表征，这被认为与万尼尔函数的中心本质上相关。在这项研究中，证明了二阶拓扑绝缘体的存在，其特征是一对部分简并的光子带。这些源于全电介质光子晶体中的非对称滑移对称性。最大局域 Wannier 函数 (MLWF) 的中心始终位于原点，但相对于组成偏振的总和并不等效。因此，拓扑角模式可以通过在样本边界处截断的明显混合的 MLWF 来识别。通过全波数值模拟与微波实验相结合，二阶拓扑得到了明确的确认和表征。这些拓扑角态表现出明显独特的模态对称性，这是通过万尼尔能带的反转而成为可能的。这些结果提供了一种探索高阶拓扑物理的替代方法，在集成和量子光子学中具有巨大的应用潜力。