Fig. 1. Structural diagram of metamaterial absorption unit. (a) Three-dimensional diagram; (b) top-layer structure; (c) two-dimensional diagram

Fig. 2. Absorption spectra of proposed broadband absorber under different conditions

Fig. 3. Simulated absorption spectra of proposed broadband absorber

Fig. 4. Real and imaginary parts of relative impedance of proposed broadband absorber

Fig. 5. Surface current distribution of proposed broadband absorber under normal incidence when E_f=1.3 eV

Fig. 6. Effects of graphene Fermi energy levels on structural properties of proposed absorber. (a) Absorption spectra of proposed absorber under different graphene Fermi levels; (b) power loss density distributions of top patterned graphene layer at resonant frequency of 6.50 THz

Fig. 7. Absorption spectra of proposed broadband absorber under different polarization angles

Fig. 8. Schematic of oblique incidence of light wave under each polarization mode. (a) TE polarization mode; (b) TM polarization mode

Fig. 9. Absorption efficiency versus frequency and angle of incidence under each polarization mode. (a) TE polarization mode; (b) TM polarization mode

Fig. 10. Model based on transmission line theory. (a) Equivalent circuit diagram of broadband absorber; (b) comparison of absorption spectra