Anisotropy-Dominated Topological Transitions for Photonic Crystals

Topological photonic insulators can robustly transport light along a topologically protected interface and have proven to be a promising platform for light manipulation. As a classical structure, two-dimensional Z₂ photonic crystals with expanded /shrunken honeycomb lattices have been verified to be topologically trivial recently. Herein, we propose a generalized platform of rotation-steered non-trivially topological photonic crystals with anisotropic pillars in a honeycomb lattice, and construct an effective theoretical model to precisely predict the formation of Kramers degeneracy. Furthermore, we reveal that the degenerate states of the platform are anisotropy-tunable but material-independent. We also investigate the geometry-tunable nontrivial topology of the photonic crystals with anisotropic pillars. Our work provides a framework for exploration of novel topological photonic devices with great flexibility and diversity.