Valley-dependent corner states in honeycomb photonic crystals without inversion symmetry

We study topological states of honeycomb photonic crystals in the absence of inversion symmetry using plane wave expansion and finite element methods. The breaking of inversion symmetry in honeycomb lattice leads to contrasting topological valley indices, i.e., the valley-dependent Chern numbers in momentum space. We find that the topological corner states appear for 60 degrees degree corners, but absent for other corners, which can be understood as the sign flip of valley Chern number at the corner. Our results provide an experimentally feasible platform for exploring valley-dependent higher-order topology in photonic systems. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

In this study, we investigate the topological states of honeycomb photonic crystals without inversion symmetry using plane wave expansion and finite element methods. Our findings show that topological corner states appear at 60 degree corners, but are absent at other corners, suggesting a sign flip of valley Chern number at the corner. This research provides an experimentally feasible platform for exploring valley-dependent higher-order topology in photonic systems.