Dynamically controllable terahertz absorber based on a graphene-vanadium dioxide-metal configuration

Metamaterials have attracted much attention due to their subwavelength scales, especially in the field of designing terahertz devices. In this paper, a graphene-vanadium oxide (VO2) composite aluminum (GVCA) metamaterial absorber with two-dimensional control properties is designed. The simulation results show that the number of narmwband absorption peaks in the absorption spectrum can be switched through the phase transition characteristics of VO2. The number of narrow-band absorption peaks before and after the phase transition is one and two, and the absorption efficiency is 100% and 90%, respectively. The physical mechanism of narrowband absorption peaks is analyzed by electric field and surface current distribution. The influencing factors of narrowband absorption peaks are explored, including the line length of graphene, the linewidth of graphene and the side length of VO2. Through active regulation of the graphene Fermi level, the absorption bandwidth can completely cover the entire frequency band of 0.1-1.1 THz, and the absorption efficiency can be maintained at about 90%. For different linear polarized (LP) waves, the influence of the incident angle on the absorption performance is studied respectively. This work promotes the application of metamaterials in THz imaging, sensing, and cloaking.