Guided-mode waves structure of electric and magnetic dipole resonances in a metamaterial slab

Abstract

The electric dipole (ED) and magnetic dipole (MD) resonances in a slab of dielectric nanostructures induced by oblique light incidence were analyzed in terms of guided-mode wave theory for transverse electric (TE) and transverse magnetic (TM) polarization. Owing to the symmetry breaking in TE and TM polarizations at oblique incidences of light, the resonance modes produced different features, which were analyzed with comprehensive studies of energy fluxes associated with the resonance modes. The MD resonances are excited by the guided-mode wave with an energy flux in the opposite direction in the incident plane for TM polarization and excited by two guided-mode waves with energy fluxes orthogonal to the incident plane for TE polarized light. Meanwhile, the ED resonances are excited by the guided-mode waves with energy fluxes in both directions, incident plane, and out of the incident plane for both TE and TM polarizations. The proposed analyses provide clear explanations of the stability or vanishing of resonance modes, with variations in the inter-distance between nanostructures near the Rayleigh anomaly condition, which were verified by the experimental measurements performed with 2D arrays of Si nanostructures for various incident angles with TE and TM polarizations.