Lattice effect influence on the electric and magnetic dipole resonance overlap in a disk array

Designing the shape of silicon nanoparticles has been shown to be an effective approach to increasing overlap between electric and magnetic dipole resonances thereby achieving directional scattering and decrease of reflection. Variations of disk diameter and/or height affect resonances differently and can thus result in resonance overlap. In most of the studies, the disks are arranged in a periodic array where the periodicity is varied together with disk diameter, but the role of lattice effect is neglected. Here we theoretically study a periodic array of disks and show that the contribution of the lattice effect in shifting resonance positions is comparable to the effect of the diameter change. We demonstrate that the lattice effect is important even when the wavelength of diffraction remains on the blue side from electric and magnetic dipole resonances and there are no additional lattice resonances excited. Period and disk dimensions are chosen so that the resonances overlap in the proximity of the telecommunication wavelength which is of great practical interest