Theoretical investigation of active dual-band tuning of dielectric chiral metasurfaces via Q-BICs

(GST) enables dynamic, mode-dependent chiroptical tuning: one mode provides a switchable on-off response for optical switching, while the other offers continuous, sensitive modulation for precision sensing. Eigenmode and multipole analyses trace these distinct behaviors to different dominant multipolar interferences. Consequently, this strategy delivers a reconfigurable, multifunctional platform that advances both the fundamental understanding of chiral Q-BICs and the design of integrated photonic devices.