(a) SEM image of dual frequency sample. Inset: unit cell geometry of the dual-band THz all-silicon metamaterial absorber. (b) Absorption characteristics of simulated (orange curve) and measured (green part) of dual-band. Electric field distribution for (c) 0.97 THz and (d) 1.93 THz of the dual-band absorber. Power loss density for (e) 0.97 THz and (f) 1.93 THz of the dual-band absorber [21].