Electrically created metasurfaces

Metasurfaces have enabled unprecedented control of the phase, amplitude, and polarization of optical wavefronts, providing new opportunities in areas such as negative refraction and optical cloaking. The fabrication of optical metasurfaces still requires complex processing techniques that include additive or subtractive methods. Here we electrically create metasurfaces in VO₂ thin film by using a resist layer with periodic boomerang-shaped orifices to strictly confine the metallic VO₂ antennas induced by ionic liquid gating within the insulating VO₂ matrix. The non-volatile insulator-to-metal transitionin VO₂ is due to a tiny reduction of oxygen content of the VO₂ under ionic liquid gating. Such optical plasmonic metasurfaces, with metallic VO₂ feature sizes ranging from 100 to 500 nm, allow the complete phase control (–π to π) and orthorhombic polarization switching of light in the mid infrared range. Our result represents a new paradigm for the fabrication and manipulation of optical metamaterials.