Multifunctional 2-Bit Coded Reconfigurable Metasurface Based on Graphene-Vanadium Dioxide

In this paper, a graphene-vanadium dioxide-based reconfigurable metasurface unit structure is proposed. Using the change at a graphene Fermi energy level on the surface of the unit structure to satisfy the 2-bit coding condition, four reflection units with a phase difference of 90∘ can be discovered. The modulating impact of the multi-beam reflection wave with 1-bit coding is then confirmed. Then we study the control of a single-beam reflected wave by metasurfaces combined with a convolution theorem in a 2-bit coding mode. Finally, when vanadium dioxide is in an insulating condition, the structure can also be transformed into a terahertz absorber. It is possible to switch between a reflection beam controller and a terahertz multifrequency absorber simply by changing the temperature of the vanadium dioxide layer without retooling a new metasurface. Moreover, compared with the 1-bit coded metasurface, it increases the ability of single-beam regulation, which makes the device more powerful for beam regulation.