Active control of polarization-dependent near-field coupling in hybrid metasurfaces

We present experimental results of actively controlled anisotropic near-field coupling in a metamaterial composed of two concentric in-plane split ring resonators and a closed-ring resonator functioning at terahertz (THz) frequencies. Transparency windows are observed due to the coupling effect between two dipole-like modes for both polarizations of the THz field, but at different frequencies. By properly incorporating silicon islands into the metamaterial unit cells, the transparency windows can be optically controlled with a modulation depth reaching 68% and 62% for horizontal and vertical polarizations, respectively. The results are of value for designing active THz anisotropic devices.