We propose a novel class of ultra-thin high-Q passband filters designed by properly combining different multipolar resonances sustained by an all-dielectric metasurface. A rigorous analytical model, based on surface impedance homogenization and accounting for the effects of both dipolar and the quadrupolar contributions to the overall scattering response, is derived and verified through numerical simulations. Then, it is described how it is possible to engineer the interactions between dipoles and quadrupoles in a metasurface made by core-shell spherical elements to design ultrathin and broadband dielectric mirrors with a narrow transmission band. The proposed filters exhibit high Q-factor resonances and can be implemented using realistic materials at either microwave or optical frequencies. Finally, we discuss how the proposed dielectric filters can be used to design self-filtering aperture antennas exhibiting higher out-of-band selectivity compared to those implemented through metallic resonators.
Monti, A., Alu, A., Toscano, A., Bilotti, F. (2020). Design of high-Q passband filters implemented through multipolar all-dielectric metasurfaces. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 68, 5142-5147 [10.1109/TAP.2020.3045795].