RETRACTED: Tunable plasmonic absorber in THz-band range based on graphene "arrow" shaped metamaterial (Retracted Article)

A tunable selective absorber consisting of a periodic "arrow" shaped graphene array that operates in the far infrared and terahertz range is proposed. It is achieved by depositing a set of graphene "arrow" shaped ribbon on a SiO2 dielectric spacer layer. The absorption characteristics of the structure are investigated by the Finite Difference Time Domain (FDTD) method. The results show that the maximum pure absorption rate at the resonant wavelength increases from 1.09% corresponding to Fermi energy level 0.2 eV to 12.76% corresponding to 0.8 eV, which is improved by nearly 12 times. Moreover, the relaxation time is increased from 0.1 ps to 1.0 ps with the other parameters are unchanged, and the maximum value of the pure graphene absorption peak increases from 1.62% to 11.55%. Moreover, the resonance wavelengths of the absorber possess angle insensitivity, nevertheless the absorption peak intensity is sensitive to the angle of incidence. In addition, this paper also compares the double-symmetric "arrow" shaped structure on the basis of this structure. The absorption spectrum of the structure shows a double peak phenomenon, which can achieve the purpose of selective absorption. The research results have certain guiding significance and important reference value for the design of next-generation graphene-based perfect terahertz absorbers, and the design can be applied to the fields of label-free biomedical sensing, photodetectors and photonic devices.