Dual-band tunable terahertz perfect metamaterial absorber based on strontium titanate (STO) resonator structure

A temperature-controlled dual-band terahertz perfect metamaterial absorber (MMA) based on strontium titanate (STO) resonator structure is proposed and investigated numerically. This MMA is a simple periodic array, consisting of two stacked square-shaped STO resonator structures and a copper substrate. Numerical simulation results indicate that the reflectance of the proposed MMA under room temperature T = 300 K is decreased to 2.1% and 0.2% at 0.114 THz and 0.181 THz, and corresponding absorbance is up to 97.9% and 99.8 %, respectively. Further results show that the designed MMA is polarization-insensitive, and wide-angle to the incident waves for both transverse electric (TE) and transverse magnetic (TM) modes. The simulated distributions of electromagnetic (EM) fields and power flow reveal that the observed high-level absorption is originated from the excitations of the fundamental dipole modes. Furthermore, the absorption property can be changed by varying structural parameters of the MMA and external temperature. Due to its excellent performance, the designed tunable MMA may find useful and important applications such as thermal emitter, bolometric imaging, energy harvesting, and sensing in terahertz region.