A terahertz full-adder based on VO2-integrated cascaded metasurfaces

Dynamic terahertz(THz) metasurfaces(MSs) show great potential in future electromagnetic wave computing and communication applications. Here, we present the first THz complex logic operations for realizing full-adder operation based on electrically controlled vanadium dioxide (VO₂)-integrated cascaded MSs. Owing to insulator-to-metal phase transition (IMT) characteristics of VO₂, MSs integrated with VO₂ thin film patches can act as switches to change transmittance of THz waves, achieving a high contrast ratio and enabling logic operations. The performance of cascaded MSs and the method of constructing the complex logic operations between multiple inputs and outputs are thoroughly discussed. Finite Element Method (FEM) simulation results verify the performance of each MS of the proposed full-adder. Each logic gate constructed by MS has a compact size and contrast ratio greater than 15 dB at 0.66 THz for the output ‘‘1″ and ‘‘0″ states, and 16.9 dB for the ‘‘Sum’’ operation and 15.5 dB for the ‘‘Cout’’ operation. This kind of THz full-adder potentially promotes the design and implementation of multifunctional electron-photon devices in THz computing and communication.