Topological states in a central-octagon moiré photonic lattice: Edge, corner, and floquet insulator properties

Moiré photonic lattices, created by twisting or superimposing identical periodic sublattices, have attracted considerable interest as flexible platforms for topological photonics. Inspired by the Su–Schrieffer–Heeger model, we systematically investigate edge and corner states in a central-octagon moiré lattice. By discretizing this lattice, we demonstrate that both zigzag and bearded edges support localized modes under specific coupling conditions. Employing an oblique truncation method, we construct a type-II zigzag edge and confirm its topological feature by calculating the bulk polarization, revealing a novel mechanism for topological transport. Furthermore, we discover higher-order corner modes under open boundary conditions, characterized by strong spatial localization. Extending our analysis to Floquet model, we demonstrate that topologically protected edge states persist, exhibiting robustness against structural defects. These findings enhance our understanding of moiré photonic lattices and pave a new way for exploring and utilizing topological phenomena in photonic systems.