Design and measurement of a narrow band metamaterial absorber in terahertz range

In this paper, we proposed and measured a metamaterial absorber with cross metal array in 12-28 THz range. A narrow absorption band (the absorption amplitude is 96%) is obtained at resonance frequency 19.24 THz, which is excited by the bright-bright modes coupling effect. Impedance matching is achieved at this resonance frequency between samples and free space. This absorption peak is enhanced and its resonance frequency is shifted with lattice constant reducing or structural parameter w1 increasing. The absorption peak is highly sensitive to the variation of structural parameters due to the bright-bright modes coupling effect on the cross strips. An equivalent LC circuit mode is proposed to understand the physical mechanism of the resonance frequency shifting. The effect of three gases on this absorption peak is measured. Moreover, high absorption performance is revealed when the incident angle reaches 48 degrees.