Terahertz wideband perfect absorber based on open loop with cross nested structure

Achieving broadband perfect absorption has always been a challenge for terahertz bands. Many terahertz broadband perfect absorbers have been proposed, but for most of them, bandwidth with an absorption rate greater than 99% is narrow. In this paper, a simple periodic structure consisting of an open-loop and an unconnected intersection is proposed for the near unit absorption of wideband terahertz waves. Simulation results show that when the incidence angle is less than 40°, the bandwidth with an absorption rate of over 99% fluctuates below 2.35 THz with different incident angles, and the central frequency is 9.6 THz. The physical mechanism of efficient absorption is studied by using resonance coupling theory. Our research has broad potential applications in THz coupler, filter, and electromagnetic stealth.