Topological States and Nontrivial Properties in a Decorated Honeycomb Photonic Lattice

ABSTRACT Structural engineering offers a powerful way to control light in photonic lattices, but realizing multiple topological phases within a single lattice platform remains challenging. Here, we theoretically investigate decorated honeycomb photonic lattices (DHPLs), a hybrid geometry that combines key features of honeycomb and Lieb lattices, and show that they provide a flexible platform for topological photonics. Owing to their multi‐site unit cell, DHPLs support a broad range of topological phenomena under different modulation schemes. With Su–Schrieffer–Heeger‐type coupling asymmetry, the lattice exhibits flat‐band features and strongly localized higher‐order corner states that remain robust against structural perturbations. Under longitudinal helical modulation, the system enters a Floquet topological phase and supports unidirectional chiral edge transport through dynamically broken time‐reversal symmetry. When intrinsic pseudospin–orbit coupling is introduced, the Dirac‐point degeneracy is lifted, and spin‐dependent edge states emerge, as characterized by nonzero spin‐resolved Chern numbers. These results establish DHPLs as a versatile platform for studying distinct topological phases in a unified photonic setting and suggest opportunities for high‐density topological waveguide arrays and spin‐dependent photonic devices.