Design and optical properties of dual‐resonant MPAs. a) Schematic illustration of the dual‐resonant metamaterial perfect absorber (MPA). Dimensions: L
1 = 2.99 µm, L
2 = 2.05 µm, W = 750 nm, t
1 = 100 nm, t
2 = 200 nm, t
3 = 100 nm, P = 3.6 µm. b) The simulated spectra of the dual‐resonant MPA with two perfect absorption peaks at 1740 cm–1 (λ
X) and 1200 cm–1 (λ
L). c) The electric field and charge distribution of the dual‐resonant MPA at λ
X and λ
L resonances shown in (b). I, II, i, ii: Field distribution calculated at the top surface of the nanostructure. III, iii: Cross‐sectional view of the charge distribution. Arrows indicate the direction of the current flow. d) The simulated spectra of the MPA with different polarizations, investigating its polarization‐insensitive characteristics. e) Simulated and f) measured spectra of dual‐resonant MPA with different L
1 and the same period (3.6 µm). g) Contour mapping of simulated absorption spectra of dual‐resonant MPA when changing I) L
1 only, II) L
2 only, III) L
1 and L
2 simultaneously.