A tailored broadband terahertz metamaterial absorber based on the thermal expansion feature of liquid metal

Abstract

In this paper, a novel temperature field tailored broadband terahertz absorber is proposed, which consists of the metallic mercury resonance units. When the ambient temperature (T) alters, the mercury can be expanded through the vertebral body channel, middle cross glass cavities, cylindrical hole and fill the upper cross glass cavities of such an absorber, which leads to the absorption bands changed. The simulated results indicate that when T = −30 ℃, the wideband absorption (WBA) regions over 90% can be achieved, which are located at 4.53–5.79 THz and 8.15–9.49 THz, and their relative bandwidths (RBs) are 24% and 15.5%, respectively. If T is increased to 300 ℃, such two WBA areas will move to 2.83–3.39 THz and 5.90–7.74 THz, whose RBs are changed to 18% and 13.3%. To investigate the performance of such an absorber, the effects of incident angle, polarization angle and structural parameters on the absorption are discussed. Similarly, the electric and magnetic field intensity distributions, the surface current distributions, power flow and power loss density of the presented absorber are also given to expound the physical mechanism of absorption. The scheme put forward in this paper will provide a new idea for the study of tunable absorbers.