Research on high sensing performance and multi-band terahertz tunable perfect absorption device

In this paper, a multi-band terahertz tunable perfect absorption device with high detection performance is proposed. The device has a simple structure, consisting of AlCuFe microstructure, SiO₂ dielectric layer and Au substrate, and has seven resonance peaks (M₁-M₇) with high absorption rate, with an average absorption rate of 98.4%. Because of its axisymmetric design, it has polarization-independent characteristics. Perfect absorption is confirmed by impedance matching with free space. The device offers exceptional tunability by adjusting the shape, Fermi level of the AlCuFe quasicrystal, and structural parameters. The high absorption performance arises from the synergistic effects of Cavity Resonance (CR), Guided Mode Resonance (GMR), and Localized Surface Plasmon Resonance (LSPR). It also exhibits remarkable detection performance, with a maximum refractive index sensitivity of 3704 GHz RIU^-1, a <i>Q</i>-factor of 315.59, and an FOM of 66.59 RIU^-1. These attributes underscore its potential in biomedical sensing, communication, and optoelectronic applications.