Tunable coherent perfect absorption via an asymmetric graphene-based structure

In this research, the optical absorption condition in a nanostructure slab consisting of three layers of graphene is theoretically investigated. This structure is distinct from the previous models and is a geometrically asymmetric structure. By means of Maxwell equations and the appropriate boundary conditions in the present model, the absorption coefficient is calculated. One of the most important features of this absorbent is owning 100% absorption at the incident angles smaller than reported in the previous works that makes this nanostructure much more applicable in integrated carbon-based photonics, especially graphene-based photodetectors. In this structure, one can reduce the incident angle which leads to coherent perfect absorption (CPA) at 16.29. Furthermore, by doing the optimization analysis, the optimal parameters for achieving the CPA condition are estimated.