THz polarization conversion metamaterial based on bianisotropic response of split-ring resonators

In this paper, we propose a novel polarization conversion mechanism based on bianisotropic response of split ring resonator (SRR) metamaterial. It is found that under oblique incidence condition with the incident terahertz electric field parallel to the SRR gap, the magnetic field component of the incident wave can excite the fundamental LC resonance of SRR and form an electric dipole perpendicular to the SRR gap, which radiates orthogonal electric field thus resulting in polarization conversion. Numerical simulations and experiments are performed to verify this idea and the results are in excellent agreement. This study contributes to our understanding of the bianisotropic electromagnetic response of SRR and opens new opportunities for creating high-efficiency and low-loss polarization conversion devices in THz or other frequencies using bianisotropic metamaterials.