Topological phase transition of photonic Chern insulators by multi-Mie-resonance inversion

The atomic orbital, as an intrinsic degree of freedom, is critical in improving band-tailoring tactics in condensed-matter physics. In photonics, analogously to atomic orbitals, multiple Mie resonances provide an effective way for photonic band engineering. In this work, we demonstrate the topological phase transitions in photonic Chern insulators imposed by band topology through multiple Mie resonances. By continuously adjusting geometric parameters and the external magnetic field in a two-dimensional gyromagnetic photonic crystal, we present the inversion of Mie resonances together with alterations in the Chern number for the corresponding photonic band. Furthermore, we propose a hetero--photonic structure that combines photonic lattices with distinct Chern numbers and exhibits chiral edge states at the heterointerface. A simple magnetic regulation approach is also provided for effective control of the edge state's on--off switching. Our work establishes a correlation between the band topology of photonic Chern insulators and Mie resonances, contributing to advancements in higher-band-topology research.