Observation of the Generalized Kerker Effect Mediated by Quasi-Bound States in the Continuum

The generalized Kerker effect (GKE) arising from the interference of high-order multipoles has attracted more interest due to its direct correlation with various functionalities in nanophotonics. The realization of the GKE at oblique incidence is highly desired yet remains underexplored. Herein, we report the experimental observation of the GKE by leveraging quasi-bound states in the continuum (QBICs) supported by a silicon metasurface. The low-Q leaky mode resonance interacts with one of the high-Q QBICs under oblique incidence, leading to the formation of a hybrid magnetic quadrupole (MQ)-magnetic dipole (MD) mode. The amplitude of the hybrid MQ-MD mode can be precisely controlled to achieve an out-of-phase condition by varying the incident angle, resulting in a GKE under the second Kerker condition. Our results reveal that the QBICs associated with rich multipole resonances can provide a new paradigm for tailoring the GKE, suggesting important implications for advanced metadevices.