Tunable mid-infrared absorber based on Dirac metamaterials

In this paper, a tunable metamaterial absorber based on a Dirac semimetal is proposed. It consists of three different structures, from top to bottom, namely a double semicircular Dirac semimetal resonator, a silicon dioxide substrate and a continuous vanadium dioxide (VO 2 ) reflector layer. When the Fermi energy level of the Dirac semimetal is 10 meV , the absorber absorbs more than 90% in the 39.06–84.76 THz range. Firstly, taking advantage of the tunability of the conductivity of the Dirac semimetal, dynamic tuning of the absorption frequency can be achieved by changing the Fermi energy level of the Dirac semimetal without the need to optimise the geometry and remanufacture the structure. Secondly, the structure has been improved by the addition of the phase change material VO 2 , resulting in a much higher absorption performance of the absorber. Since VO 2 is a temperature-sensitive metal oxide with an insulating phase below the phase transition temperature (about 68 °C) and a metallic phase above the phase transition temperature, this paper also analyses the effect of VO 2 on the absorptive performance at different temperatures, with the aim of further improving absorber performance.