Fig. 1. (a) Fabrication procedure of MIM moiré superabsorbers with variable parameters (i.e., spacer thickness d, rotation angle θ, and filling factor). (b)-(d) Moiré metasurfaces with variable rotation angles of 10°, 15°, and 20°, respectively. (e) 20° moiré metasurface with a higher filling factor than that in (d). (f), (g) Scanning electron micrographs of Au moiré metasurfaces. The scale bar is 2 μm.

Fig. 2. (a) Unit vectors in the hexagonal hole array. (b) A rectangular area in the hexagonal hole array using V(5,8) and V′(1,6) as the length and width separately. (c) The same area as (b) but with a relative ∼15° rotation angle. (d) A unit cell in the moiré pattern with a relative ∼15° rotation angle. (e) A unit cell for 10°, 15°, and 20° moiré metasurfaces.

Fig. 3. (a) Cross-sectional view of r12′, r21′, t12′, and t21′ in decoupled mode theory. (b) The simulation model to calculate the parameters r12′, r21′, t12′, and t21′. (c) The simulated reflection/transmission phase and amplitude coefficients for a 15° rotation angle moiré metasurface.

Fig. 4. (a) Simulated (black dashed line) absorption for a 15° rotation angle pristine (no spacer) moiré metasurface; simulated (dashed red and blue line) and calculated (solid black line) results comparison for a 15° rotation angle moiré MIM structure with 800 nm spacer thickness. The PML boundary is applied in the simulation. (b) Simulated (dashed line) and calculated (solid line) results comparison for different rotation angles at 800 nm spacer thickness. The periodic boundary is applied in the simulation.

Fig. 5. (a) Calculated narrowband absorber with an optimized spacer thickness (1300 nm) at different rotation angles. (b) A calculated broadband absorber with an optimized spacer thickness (900 nm spacer for 10°, 800 nm spacer for 15°, and 700 nm spacer for 20°).

Fig. 6. (a) Simulated polarization-dependent broadband absorption for a 20° moiré MIM structure with an optimized spacer thickness. (b) Simulated polarization-dependent narrowband absorption for a 20° moiré MIM structure with an optimized spacer thickness.

Fig. 7. Simulated visible-NIR absorption spectra of a 10° moiré MIM structure with different spacer thicknesses.

Table 1. m, m′, n, and n′ Values for Different Tolerance Factors as θ Equals 15°

Table 2. m, m′, n, and n′ Values Used in Simulation for Different Rotation Angles