Tunable terahertz absorber based on graphene-metal nanostructure as opto-fluid sensor

In this paper, strong and effective absorber is achieved using graphene-metal nano structures. Proposed structures are consisted of multi layers of graphene and metals. By introducing ring shaped graphene layers, the near unity absorption coefficient can be obtained. The effects of different structural parameters like the length, radius and width (h1, t1, a, h2, t2, a1) and chemical potential (Ef) on the absorption spectrum (wavelength and value) are also investigated. The best resonant peak is obtained for the structure with two rings and straight waveguides. The proposed structure can be used as an effective sensor for sensing opto-fluidic materials with different refractive indices (from 1.0006 to 1.6209). The designed structure can be utilized as a strong absorber or sensitive sensor in optical communication or other optical nano systems.