Figure 1.
(a) Schematic diagram of the ultra-broadband adjustable metamaterial absorbing structure based on VO2. Four-ring nested VO2 periodic array structure with thickness of 0.5 μm is embedded between two layers of SiO2. Bottom layer is 1 μm-thick VO2 film. At 358 K, VO2 transforms into metal state, and the structure exhibits THz broadband absorption characteristics. (b) Side-view and (c) top-view of unit cell. Geometric parameters are p = 90 μm, r1 = 42 μm, r2 = 34 μm, r3 = 25 μm, r4 = 19 μm, t1 = 22 μm, t2 = 39 μm, d1 = 1 μm, d2 = 0.5 μm, and w = 2 μm, respectively.