Metasurface-Based Optical Liquid Crystal Cell as an Ultrathin Spatial Phase Modulator for THz Applications

A concept of an efficient ultrathin spatial phase modulator for correcting terahertz wavefronts in transmission with subwavelength spatial resolution is experimentally demonstrated. It exploits a combination of spatially addressable resonant planar metamaterials (so-called metasurfaces) and an optically thin (<0.04λ) low-voltage (<20 V) liquid crystal cell. The device allows "imprinting" of a 2D phase profile of any spatial complexity with a spatial resolution better than 0.23λ and can be readily fabricated using the well-established LC-device technology and high-resolution photolithography technique.