Interplay between out-of-plane magnetic plasmon and lattice resonance for modified resonance lineshape and near-field enhancement in double nanoparticles array

Two-dimensional double nanoparticles (DNPs) arrays are demonstrated theoretically supporting the interaction of out-of-plane magnetic plasmons and in-plane lattice resonances, which can be achieved by tuning the nanoparticle height or the array period due to the height-dependent magnetic resonance and the periodicity-dependent lattice resonance. The interplay of the two plasmon modes can lead to a remarkable change in resonance lineshape and an improvement of magnetic field enhancement. Simultaneous electric field and magnetic field enhancements can be obtained in the gap regions between neighboring particles at two resonance frequencies as the interplay occurs, which present open cavities as electromagnetic field hot spots for potential applications on detection and sensing. The results not only offer an attractive way to tune the optical responses of plasmonic nanostructure, but also provide further insight into the plasmons interactions in periodic nanostructure or metamaterials comprising multiple elements.