Dual-band tunable perfect absorber based on monolayer graphene pattern

In this paper, we propose a metamaterial perfect absorber (MPA), which is a three-layer structure composed of a periodically placed "(sic)" type graphene array on top of a gold layer separated by a SiO2 dielectric spacer, to achieve dual band perfect absorption. The absorption mechanism is analyzed, and the simulation results show that at the frequencies of 5.16 THz and 10.30 THz, the absorption rates are as high as 99.7% and 99.6%, respectively. In addition, the absorber is insensitive to the polarization of the incident wave and has a good tolerance to the incident angle. Moreover, the position and peak absorption of the absorber can be adjusted flexibly by changing the structure parameters and the Fermi level mu(c) of graphene. In addition, the position of absorption frequency is sensitive to the surrounding medium, so the proposed MPA has potential applications in the field of refractive sensor. This paper provides a new idea for the design of tunable dual-band ideal terahertz absorber. Because of its good performance, the proposed absorber has a wide range of application prospects in terahertz and mid-infrared optical filter, optical sensor, and radiation thermal imaging, stealth and communication fields.