Quadrupole Mie-resonant metamaterial

Dense photonic crystal lattices can serve as artificial materials, with light propagation in these structures described by effective material parameters that surpass the capabilities of natural materials. In this study, we present a metamaterial that supports magnetic quadrupole polarization—a property rarely observed in existing structures. We experimentally demonstrate a magnetic quadrupole metamaterial associated with Mie-resonance-excited stop bands below the Bragg band. Additionally, we develop a theoretical model that addresses both dispersion and boundary conditions within this framework. Using the Fabry–Perot resonator as a case study, we validate our model and reveal that the quadrupole metamaterial can exhibit markedly different reflection and transmission spectra, including zero reflection at normal incidence. Our findings highlight the practical potential for both experimental and theoretical investigations of metamaterials that extend beyond the dipole approximation.