Abstract
In this paper, we designed a dynamically tunable four-band perfect sensor based on bulk Dirac semimetal (BDS). The sensor comprises a top BDS layer, a bottom Au layer, and an intermediate dielectric layer. Four resonant modes with >98 % absorption are achieved in the range of 9–11.8 THz. Due to the rotationally symmetric design, the sensor is polarization insensitive. The formation mechanism of perfect absorption is explained using the principles of impedance matching. We also determined the effects of structural parameters and Fermi energy of the BDS on the absorption spectra. We explain the blue-shift and red-shift phenomena of the resonant frequency based on equivalent circuits. Additionally, we define the refractive index sensitivity (S) and find that the maximum sensitivity is 516 GHz/RIU. Due to these excellent properties, our design provides a way of thinking about actively tunable terahertz sensors and expands their application scope.
Published Version
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