Configurable topological photonic polycrystal based on a synthetic hybrid dimension

Topological photonic structures exhibit resilience to defects, allowing unidirectional light flow and promoting the development of robust devices with large information processing capacities. However, the diversity of topological boundary modes is typically governed by bulk-edge correspondence, which limits multidimensional multiplexing and the integration density of next-generation photonic systems. Here, we present a polycrystal approach based on domain wall engineering to configure multi-band dispersion in a synthetic hybrid dimension by utilizing orientation freedom. As a prototype, we demonstrate that an all-dielectric platform for hybrid topological polycrystalline photonic integrated circuits can support up to eight edge channels and four corner modes via pseudospin-valley Hall effect, empowering controllable directionality of multi-frequency and spinful channels with highly localized performance. Our findings reveal a photonic architecture that significantly advances the on-chip integration of topological photonics, offering valuable potential for future information processing technologies across optical and microwave frequencies.