Topological Chiral Edge States in Deep‐Subwavelength Valley Photonic Metamaterials

Topological valley photonics has emerged as a new frontier in with many promising applications. Previous boundary transport relies on kink states at internal boundaries between two topologically distinct domains. However, recent studies have revealed novel class of topological chiral edge (CESs) external materials, which remained elusive photonics. Here, CESs are proposed and experimentally demonstrated photonic metamaterials (VPMMs) by accurately tuning on-site potentials. Moreover, the VPMMs work deep-subwavelength scales. Thus, supported highly confined self-guiding without relying cladding layer to prevent leakage radiation. Via direct near-field measurements, bulk bandgap, dispersions, robust passing through sharp corners, hallmark signatures CESs, observed. This paves way explore sheds light miniaturized devices.