Analysis and Design of a Hybrid Graphene/Vanadium-Dioxide Terahertz Metasurface with Independently Reconfigurable Reflection Phase and Magnitude

A reconfigurable THz metasurface (MS) capable of independent reflection amplitude and phase modulation is designed and analyzed. The tunability is achieved in a simple few-layer structure by control over the chemical potential of a graphene monolayer patterned in square patches and over the bulk conductivity of an overlying vanadium dioxide (VO2) patch array; these impart control over the reflection phase and magnitude, respectively. To design and analyze the MS unit cell, we employ intuitive equivalent circuit and transmission line modeling, which is validated against full-wave simulations, showing good agreement in the regime of interest, i.e., on the first resonance for normal plane wave incidence. The simulated phase modulation approaches 250°, enabling binary-encoded digital metasurface designs, while the magnitude modulation spans more than 20 dB, from −3 dB almost down to perfect absorption. The flexibility of dynamic phase and amplitude control can unlock the full potential of such THz MS hybrid designs for future wireless communications (6G and beyond) and for sensing applications. Finally, the analytical modeling can be extended to polarization-dependent, anisotropic, or non-local EM responses and/or to include aspects of the multiphysical control mechanisms.