Temperature insensitive ultra-broadband THz metamaterial absorber based on metal square ring resonators

Abstract The temperature independent ultra-broadband THz metamaterial absorbers based on square resonator are designed. The absorber is composed of surface metal resonance ring, intermediate medium layer (SiO2) and bottom metal plate. Based on the multi-band absorption of the single-layer and single square ring resonant structure, the different multi-layer structures of four square resonant rings are designed to achieve the ultra-broadband high absorptions. The affects of the structural parameters on the absorption are discussed. The optimization results show that the average absorptance of the designed absorber is 94.70% in the frequency range of 2.07 to 3.63 THz, with the bandwidth 1.56 THz. It is also found that the absorptances of strontium titanate (STO) material embedded in the metal resonant rings have little change in the temperature range from 200 K to 400 K and it shows the temperature insensitivity for the designed structures. The proposed broadband terahertz metamaterial absorbers have potential applications in the fields of heat resistance, terahertz imaging and electromagnetic stealth.