A Simple Triple-Band Terahertz Metamaterial Absorber Based on Multi-Mode Resonance for Sensing Applications

A simple design of a triple-band terahertz metamaterial absorber is presented in this paper. The proposed absorber only uses a cross metal structure to achieve nearly perfect absorption of the three peaks, and the absorptivities are all over 97%. The structure shows excellent triple-band absorption by combining fundamental mode resonance with high-order resonance (third-order resonance) in a single metal structure, the absorption mechanism is different from most previous multi-band absorbers. By adjusting the structural parameters of the cross metal, a frequency tunable triple-band absorber is obtained. The metal structure is not only simple in graphics but also insensitive to the polarization waves, which is beneficial to manufacturing and practical application. Finally, the sensing performance of the absorber is analyzed in detail by changing the surrounding environmental parameters, which shows that the absorber has great application value in detection and sensing.