Optically reconfigurable higher-order valley photonic crystals based on enhanced Kerr effect.

The reconfigurable higher-order topological states are realized in valley photonic crystals with enhanced optical Kerr nonlinearity. The inversion symmetry of the designed valley photonic crystal is broken due to the difference in optical responses between adjacent elements rather than their geometry structures. Therefore, by constructing photonic crystals with distinct topological phases, valley-dependent topological states can be realized, and their reconfigurability is demonstrated based on the Kerr effect. The investigated higher-order topological photonic crystals exhibit great robustness against the structural defects and inferior quality of pump introduced around the corner. Our work provides a new, to the best of our knowledge, platform for studying optical field manipulation and optical devices fabrication in the context of nonlinear higher-order topology.