Integrated Air Spaced Terahertz Metamaterial Absorber with High Quality Factor

In this paper, we present a polarization insensitive air-spacer triple band absorber. With the fabricated absorber, the three near unity-absorption peaks can be fine controlled with different structure designs, which have a great advantage in variety applications. Also, with air instead of the traditional dielectric layer, the absorber will exhibit an extremely high quality factor (Q) compare with the one in dielectric layer. Moreover, with the air-spacer triple band absorber structure, the coupling between the metamaterials layer and the ground plane is very strong. As a result, the near-field interaction should be considered in the interference theory. With the coupling effect included, the correctional interference theory can well predict both the numerical and experiment results of the metamaterial perfect absorber. Our findings demonstrate that the capacitance increase and the inductance decrease are the causes of the difference between the interference theory and the simulation and experiment results especially for circles metamaterials structures with thin air-spacer in metamaterial perfect absorber.