Affiliation:
1. The MOE Key Laboratory of Weak‐Light Nonlinear Photonics TEDA Applied Physics Institute and School of Physics Nankai University Tianjin 300457 China
2. INRS‐EMT 1650 Blvd. Lionel‐Boulet, Varennes Quebec J3×1S2 Canada
3. Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan Shanxi 030006 China
Abstract
AbstractKagome lattices represent an archetype of intriguing physics, attracting a great deal of interest in different branches of natural sciences, recently in the context of topological crystalline insulators. Here, two distinct classes of corner states in breathing Kagome lattices (BKLs) with “bearded” edge truncation are demonstrated, unveiling their topological origin. The in‐phase corner states are found to exist only in the topologically nontrivial regime, characterized by a nonzero bulk polarization. In contrast, the out‐of‐phase corner states appear in both topologically trivial and nontrivial regimes, either as bound states in the continuum or as in‐gap states depending on the lattice dimerization conditions. Furthermore, the out‐of‐phase corner states are highly localized, akin to flat‐band compact localized states, and they manifest both real‐ and momentum‐space topology. Experimentally, both types of corner states are observed in laser‐written photonic bearded‐edge BKLs, corroborated by numerical simulations. The results not only deepen the current understanding of topological corner modes in BKLs but also provide new insight into their physical origins, which may be applied to other topological BKL platforms beyond optics.
Funder
National Natural Science Foundation of China
Natural Science Foundation of Tianjin Municipality
Higher Education Discipline Innovation Project
National Basic Research Program of China
Subject
Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials