Fig. 1. Schematic diagram of a terahertz broadband tunable metamaterial absorber based on graphene and vanadium dioxide

Fig. 2. When the top I-shaped resonator is at an angle of 45° with the X-axis (a) the absorption spectrum of the absorber and (c) the real and imaginary parts of the relative impedance of the absorber; When the top I-shaped resonator is perpendicular to the X-axis (b) the absorption spectrum of the absorber and (d) the real and imaginary parts of the relative impedance of the absorber

Fig. 3. When the Fermi level of graphene is 0.1 eV and the conductivity of vanadium dioxide is 200 000 S·m^-1, The top and bottom surface current distribution at f₁=1.87 THz, f₂=3.04 THz, f₃=4.16 THz

Fig. 4. Absorption spectra of different structures

Fig. 5. Absorption spectra of metamaterial absorbers under different Fermi levels of graphene

Fig. 6. (a) Absorption spectra of metamaterial absorbers with different VO₂ conductivities; (b) Top view of electric field intensity distribution at 3.04 THz when the conductivity of vanadium dioxide is 100 S·m^-1; (c) Top view of electric field intensity distribution at 3.04 THz when the conductivity of vanadium dioxide is 200 000 S·m^-1

Fig. 7. Influence of different structural parameters on absorber absorption performance
(a): I-shaped thickness T₁; (b): Length of I-shaped middle strip L₁