Robust gapped surface states and filtering effect in a photonic topological gyroelectromagnetic metamaterial

Abstract

The recent reported robust surface states in a photonic metamaterial are usually limited to the gapless type. In this work, we propose a photonic topological metamaterial that can support surface states with gaps. The gaps appear when the electromagnetic duality symmetry of the material system is broken. Despite the existence of gaps, the surface waves can still bypass sharp corners robustly. We further demonstrate the filtering effect which can be viewed as a fingerprint of the existence of the gapped surface states. By changing the electromagnetic parameters of the covering materials, the filtering effect with controllable bandwidth can be realized.