Theoretical design of an electrically and thermally dual-controlled double-band absorber based on graphene and InSb

A novel, to our knowledge, double-band metamaterial absorber based on graphene and InSb is proposed in the terahertz regime. The amplitude and center frequency of the absorber can be electrically tuned by adjusting the graphene chemical potential and thermally controlled by varying the InSb temperature independently. First, owing to the bright–bright mode coupling effect, the average absorption rate of double-band absorber can reach 97% in the FDTD simulation. Meanwhile, the physical absorption mechanism can be analyzed theoretically by the radiating two-oscillator model. Second, when the chemical potential of graphene increases, the absorption rates of the absorber decrease gradually, and the absorption frequencies are almost unchanged. Moreover, if the temperature of InSb increases, the absorption frequencies and rates of absorber increase simultaneously. Finally, the impact of parameters on the absorption spectra, and the excellent sensing performance of the dual-band absorber as a refractive index sensor, are further discussed. This work provides a theoretical basis for the designs of dual-tunable absorbers and sensors.