Kirigami-actuated reconfigurable topological photonic crystals

Photonic crystals are typically fabricated with a fixed topology, freezing their edge and corner states in space and frequency. Here we introduce a kirigami-actuated reconfigurable topological photonic crystal in which a single in-plane rotation reshapes the unit cell, drives a bandgap closure and reopening, and thereby relocates the Wannier center and switches the associated Zak phase—the topological invariant that determines whether boundary states appear. We engineer a symmetry-preserving square-lattice deformation path that programs the intracell rod configuration into a compact, discrete topological phase library. Using this library, we demonstrate reconfigurable control of topological modes in both resonance frequency and spatial localization from the same mechanical degree of freedom. A higher-order corner mode is switched between two distinct resonance frequencies while its localization moves between different geometric corners. Meanwhile, at a fixed operating frequency, the propagation path of reciprocal crystalline-symmetry-protected edge modes is mechanically rewritten, enabling on/off gating and two-path beam routing. These results establish a route toward reconfigurable topological photonic devices, showing that quantized band topology can be encoded and switched by shape. Using kirigami, the authors create a photonic crystal whose topology can be mechanically reconfigured, allowing corner states and light-routing paths to be switched after fabrication.