A three-dimensional ultra-broadband and polarization insensitive metamaterial absorber and application for electromagnetic energy harvesting

Abstract

ABSTRACT In this paper, a three-dimensional (3D), ultra-broadband and polarization insensitive metamaterial absorber (MA) base on the metal loading resistive films structure was introduced. Numerical results show that ultra-wideband absorption more than 90% can be achieved from 4.8 to 14.67 THz, the relative bandwidth up to 101%. The reason of the highly efficient absorption is contributed to the metal Ohm loss and load absorption of the resistive film in the gap of metallic SRRs (split-ring resonators) mainly. Importantly, we found loading resistive film in the gap of the metal-film can significantly promote absorption. Circle currents are formed on twelve SRRS and the electromagnetic energy is collected on the resistive films. The surface currents are researched to explain the physics mechanism of the MA. Moreover, the harvesting efficiencies for energy on the normal and oblique incidences are investigated. Finally, we calculated the HPBW (Half Power Band Width) of harvesting efficiency, a characteristic with dual-band half power absorption is obtained.