High sensitivity dual-band perfect plasmon absorber based on graphene split-ring-resonator

In this paper, a dual-band tunable perfect plasmon absorber based on graphene split-ring-resonator is proposed. The device is composed of resonant ring graphene with an open top layer, a thick PMMA spacer layer and a Cu substrate mirror layer, which has simple structural characteristics. By FDTD simulation method, the numerical results show that perfect absorption is achieved at resonance wavelengths lambda(A) = 39.30 mu m and lambda(B) = 62.00 mu m, and the absorption rates are 99.55% and 99.64%, respectively. By adjusting the geometric parameters of graphene array, changing the structural period P and PMMA dielectric thickness, the absorber can achieve perfect absorption. In addition, the resonance wavelength and absorption peak of the absorber can be effectively tuned by controlling the chemical potential, relaxation time and dielectric constant inside the absorber. At last, we exposed the structure to different environmental refractive indices, and calculated the corresponding maximum sensitivities of the two resonant modes as SA = 13.82 mu m/RIU and S-B = 21.47 mu m/RIU. The maximum figure of merit are FOM1 = 4.4870 RIU-1 and FOM2 = 3.5148 RIU-1 respectively. Therefore, the design of graphenebased tunable perfect metamaterial absorber proposed in this study can be applied to photodetectors, sensors and other fields.