Polarization-Independent Plasmon-Induced Transparency in a Fourfold Symmetric Terahertz Metamaterial

Metamaterials that reveal fascinating and unique resonant properties allow for adequate control of electromagnetic waves at will. Recently, considerable studies have shown that the plasmon-induced transparency (PIT) effect can be realized by metamaterials via destructive interference between different resonance modes; however, most of them are sensitive to the polarization of incident wave. Here, we demonstrate a polarization-independent PIT metamaterial functioning in the terahertz regime. The proposed structure has a fourfold symmetry and exhibits a typical PIT behavior due to the coupling effect of four different modes, yielding polarization-independent characteristics.