Triple-band terahertz metamaterial absorber using surface structure of two metallic split rings of same-size connected by a non-centrally-placed metallic strip.

A triple-band terahertz (THz) metamaterial absorber is suggested in this paper, which is formed by the sandwich design strategy consisting of a patterned surface structure on top of a gold substrate separated by an ultra-thin thickness of 14 μm dielectric spacer. This patterned surface structure is composed of two same-sized gold split rings connected by a gold strip, which is slightly deviated from the geometric center, resulting in unequal dimensions on the left and right sides of the surface structure. This metamaterial structure can achieve three near-perfect absorption peaks (labeled P1, P2 and P3) at terahertz region. The three absorption peaks achieved the absorption of 99.94, 97.67 and 98.71% respectively. The frequencies of the three discrete absorption peaks are P1 = 1.15 THz, P2 = 1.88 THz and P3 = 1.98 THz respectively. The number of absorption peaks and the resonance frequencies of these peaks can be adjusted by changing the deviation position of the connecting gold strip and the parameters of the two gold split rings. When the gold strip is located in the geometric center, only two absorption peaks can be obtained. When it deviates from the center position, the number of absorption peaks will change, and three resonance absorption peaks will be obtained. In addition, the width and length of the two gold split rings can change the resonance frequencies of the three absorption peaks. These results show that the suggested THz metamaterial absorbers have broad application prospects in sensing, detection, imaging and other fields. [ABSTRACT FROM AUTHOR]