A five-peaks graphene absorber with multiple adjustable and high sensitivity in the far infrared band

In this paper, a multi-band and multi-adjustable narrowband perfect absorber in the far infrared band is proposed. The absorber is a traditional MPA structure, the top layer of the unit absorber is composed of a graphene array with four open rings embedded with four-angle star patterns. The middle layer is a SiO2 dielectric layer, and the bottom layer is a gold substrate. We have studied the plasmon resonance on the surface of graphene in the incident far-infrared wave. Our absorber has five absorption peaks, and the absorption rates at the frequencies of 96.3083 THz, 103.6 THz, 105.862 THz, 117.108 THz and 123.572 THz are 98.731 %, 99.993 %, 99.794 %, 99.819 % and 99.128 % respectively, which is perfect absorption. Then we have studied the adjustability of the absorber by changing the chemical potential energy, relaxation time and refractive index direction of the dielectric layer of graphene, It is proved that the absorber can dynamically adjust the absorption frequency of the absorber in multiple directions. Finally, we discussed the practicability of the absorber, which has a sensitivity of up to 22.04 THz/RIU, and is not sensitive to the polarization angle (0° - 60°). Compared to previous absorbers, we not only have good tunability, but also have higher sensitivity and more absorption peaks. We believe that our research will bring new ideas to multi-band and multi-adjustable narrow peak metamaterial absorber. In the future, I believe our absorbers will shine brilliantly in the fields of high sensitivity sensors, photothermal detection and thermal radiation.