A polarization-independent and ultra-broadband terahertz metamaterial absorber studied based on circular-truncated cone structure

Abstract

In this paper, we present an ultra-broadband polarization-independent terahertz (THz) metamaterial absorber (MA) made of circular truncated cone metamaterial. Absorptivity higher than 92.3% at normal incidence is obtained in a wide range of frequencies from 2 to 10 THz. We employ an isotropic metamaterial cell which consists of alternating layers of Au metal and SiO2 dielectric spacer. The absorption spectra of the THz MA are calculated using the finite-difference time domain (FDTD) method within the CST Microwave Studio 2009 in the frequency range of 0–10 THz. Our broadband absorber can be regarded as a group of micro-absorbers perpendicularly stacked and their absorption peaks coupling to each other to form an ultra broadband absorption. This THz MA has the advantages of broadband, polarization-independent and fabrication facility, and thus can be widely applied in THz wave harvesting, detection, spectrum imaging and stealthy technology.