Fig. 1. Relationship among surface impedance, chemical potential, and frequency of graphene

Fig. 2. Terahertz absorber based on monolayer graphene metamaterial. (a) Three-dimensional structure diagram; (b) top view of unit

Fig. 3. Absorption spectra of metamaterial absorber under different structural parameters. (a) Outer radius r₂ of graphene ring is between 1.0 μm and 1.8 μm; (b) inner radius r₁ of graphene ring is between 0.05 μm and 0.45 μm; (c) dielectric thickness t is between 7.6 μm and 9.2 μm

Fig. 4. Electric field intensity distribution of terahertz absorber at 4.48 THz frequency

Fig. 5. Variation curves of absorptivity with frequency under different values of graphene chemical potential μ_c

Fig. 6. Absorptivity of metamaterial absorbers at different polarization angles

Fig. 7. Absorption spectra of terahertz waves in different modes. (a) TE mode; (b) TM mode

Fig. 8. Structure diagram of absorber based on two-layer graphene metamaterial. (a) Three-dimensional view; (b) unit top view of upper graphene metamaterial; (c) unit top view of lower graphene metamaterial; (d) side view

Fig. 9. Absorptivity curves of terahertz absorber based on two-layer graphene metamaterial

Fig. 10. Electric field intensity distribution of absorber based on bilayer graphene metamaterial. (a) Electric field distribution of G1 layer at 4.75 THz frequency; (b) electric field distribution of G2 layer at 3.05 THz frequency

Fig. 11. Structure diagram of absorber based on three-layer graphene metamaterial. (a) Three-dimensional view; (b) unit top view of upper graphene metamaterial; (c) unit top view of interlayer and lower graphene metamaterial; (d) side view

Fig. 12. Absorptivity curve of terahertz absorber based on three-layer graphene metamaterial