Design of Six-Band Terahertz Perfect Absorber Using a Simple U-Shaped Closed-Ring Resonator

We present a simpler and novel design of a six-band terahertz perfect metamaterial absorber (MA) composed of a metal U-shaped closed-ring resonator, a dielectric spacer, and a metal back plate. The numerical simulation results demonstrate that it can perform absorption peaks at six resonant frequencies whose peaks average 97.3%. The physical mechanism of the proposed MA is explained by the multipolar plasmon resonance of the structure, thus making the structure very easy to fabricate. Furthermore, the sensing performance of the absorber is analyzed in terms of the overlayer.