A Tunable Plasmonic Perfect Absorber Based on Graphene and Two Metal-insulator Substructures

In recent decades, numerous researchers have been keenly interested in plasmonic absorbers due to their efficiency in a variety of applications such as solar cells. This is because the surface plasmons formed at the interface between metal and insulators interact strongly with light, thereby augmenting electromagnetic (EM) waves. In most cases, plasmonic absorbers featuring metal-insulated-metal structure (MIM) are favored for their robust absorption rates, straightforward fabrication process, minuscule size, and portability. This paper proposes a tunable plasmonic perfect absorber (PPA) based on graphene and two metal-insulator substructure within the 28-60 µm wavelength range. This device is simulated by 3D finite element analysis using CST software. Also, in our proposed structure, instead of using a single micro-blade, two micro-blades are arranged opposite of each other in the absorber structure through which the electric field is locally strengthened and a sharper resonance peak with greater amplitude is obtained. Simulation results demonstrate that a resonance peak is observable in the absorption spectrum of the structure and that this peak can be shifted between 30µm and 40µm by applying a gate bias voltage to the graphene nanolayer without modification of the structure's dimensions. The features of this absorber make it suitable for sensor applications, which will be further explored in future research. We also investigated the influence of dimensions on absorption to take into account the allowable tolerances and sensitivities associated with its fabrication. Furthermore, we proposed a structure that can enhance absorber performance in the future.