Fig. 1. Structure schematic diagram of the ultra wideband perfect absorber. (a) Three-dimensional overall structure; (b) top view plane; (c) propagation path

Fig. 2. Absorption and reflection curves of the device. (a) Simulated absorption and reflection curves and absorption curves calculated using MRIT theory; (b) absorption curves in TE and TM modes

Fig. 3. Absorption curves for different patterns and their corresponding electric field distribution in the Z-direction. (a) Absorption curves of individual circular; 4 L-shaped and circular + 4 L-shaped graphene; (b) top view of individual circular graphene absorber; (c) top view of 4 L-shaped graphene absorber; (d) top view of circular + L-shaped graphene absorber; (e) electric field distribution in the Z-direction corresponding to different frequency positions

Fig. 4. Distribution of electric field modes at different frequencies. (a) Electric field distribution at the left frequency position (3.02 THz) at 90% device absorption; (b) electric field distribution at 3.32 THz; (c) electric field distribution at 5.02 THz; (d) electric field distribution at 6.76 THz; (e) electric field distribution at 7.16 THz

Fig. 5. Absorption curves of the devices and their corresponding top layer patterns when changing the shape of the content graphene. (a) Absorption curves of round, orthorhombic and octagon graphene inside; (b) top layer pattern of round graphene inside; (c) top layer pattern of orthorhombic inside; (d) top layer pattern of octagon inside

Fig. 6. Absorption curve plots for different structural parameters. (a) Plot of absorption curves for different dielectric layer thicknesses d; (b) plot of absorption curves for different radii R of circular graphene; (c) plot of absorption curves for different L-shaped graphene lengths L; (d) plot of absorption curves for different L-shaped graphene widths W

Fig. 7. Absorption spectrograms for varying the angle of incidence from 0° to 70°. (a) Absorption spectrogram in TE mode; (b) absorption spectrogram in TM mode

Fig. 8. Absorption curves of the absorber at different graphene Fermi energy levels

Table 1. Comparison of tunable ultrawideband absorbers