Hybridized magnetic lattice resonances for narrowband perfect absorption

The realization of multiple sharp collective resonances and their implications for ultrathin and narrowband perfect absorber without using back reflector is promising for the design of high performance nanophotonic devices. This study proposes and demonstrates that for double metallic/dielectric core/shell nanoparticle arrays, sharp hybridized magnetic lattice resonances can be excited and used to generate narrowband perfect absorption. Both coupled dipole approximation and full-wave simulations reveal that the magnetic (electric) coupling strength and coupling phase between the two nanoparticles in a unit cell can be effectively tuned by adjusting their relative positions, which leads to the selective excitation of the magnetic (electric) lattice modes for individual nanoparticle arrays or the hybridized magnetic (electric) lattice modes for the whole structures. When the hybridized magnetic lattice resonances are spectrally overlapping with electric modes by manipulating the lattice spacing, both balanced Kerker and critical coupling conditions are satisfied, thereby resulting in the formation of narrowband perfect absorptions. The flexible tunability of multiple sharp magnetic (electric) lattice resonances and the realization of narrowband perfect absorptions make the double nanoparticle arrays a promising platform for implications of linear and nonlinear nanophotonic devices.