Creation of Fano resonances and bound states in the continuum in metallic metasurface superlattices.

Abstract

A perfect metal film with a periodic arrangement of cut-through slits, an anisotropic metallic metamaterial film, mimics a dielectric slab and supports guided electromagnetic waves in the direction perpendicular to the slits. Since the guided Bloch modes exist only below the light line, conventional metallic metamaterial films do not exhibit interesting leaky-wave effects, such as bound states in the continuum and Fano resonances. Here, we introduce metallic metasurface superlattices that include multiple slits in a period and demonstrate that the superlattices support the Fano resonances and bound states in the continuum. We show that the number of Fano resonances and bound states depend on the number of slits in a period of superlattices through rigorous finite element method simulations. Experimental results in microwave region also support the creation of Fano resonance and bound states in the continuum by the increment of the number of slits in a period of superlattices.