Ultra-thin metamaterial-enhanced liquid-crystal terahertz spatial phase modulator

We demonstrate experimentally a very thin THz spatial phase modulator based on planar metamaterials hybridysed with a liquid-crystal (LC) cell. It consists of two layers of THz planar metamaterials separated by a 12 µm thick LC layer. Besides enhancing optical anisotropy of the LC layer, the metamaterials also act as spatially addressable electrodes, which transform the resulting structure into an array of sub-wavelength pixels with independently controlled electromagnetic phase. Our approach brings about a new family of LC-enabled but optically thin THz devices for efficient control and manipulation of THz wavefronts