A modulated broadband polarimetric insensitive metamaterial absorber based on a monolayer of graphene

Abstract This paper presents a tunable and polarization-insensitive wideband metamaterial absorber based on single-layer graphene. By comparing the simulated experimental data with theoretical derivations, it was found that the absorbance of the material can be sustained above 90% in the frequency range of 2.78 to 7.14 (4.36) THz, of which the absorption rate exceeds 99% in the frequency range of 4.1–4.54 (0.44) THz, and remarkably, perfect absorption is achieved at 4.32 THz. In the range of 2.78–7.14 THz, the average absorption rate is 96.1%, by adjusting the physical size of the graphene layer pattern, we can modify the working band gap of the absorber. By applying a voltage to modulate the Fermi level of graphene, we can increase the absorption bandwidth. When the chemical potential is 1.0 eV, at the bandwidth of 4.36 THz, its absorption rate exceeds 90%. The working principle of absorbing materials was deeply explored using the principles of electromagnetic field distribution and impedance adaptation. Through detailed analysis of different polarization states and incident angles, we found that the absorber is not sensitive to polarization due to its symmetrical structure, and found that it exhibits low sensitivity at incidence angles. In addition, after comparative analysis, significant differences were observed in the absorption efficiency of the absorber under various relaxation time conditions, and the obtained data were elaborated in detail using the carrier mechanism of plasma vibration. We found that in addition to obtaining an almost perfect absorber with wide band by adjusting the parameters, it is also feasible to obtain an approximately narrow band absorber by changing the relaxation time without having to re-manufacture the structure. The absorber offers several advantages, including tunability, a wide absorption band, a high absorption rate, polarization insensitivity, and a simple structure. Therefore, this absorber exhibits great potential for absorption, monitoring, and sensing in the terahertz band.