Controlled light energy and perfect absorption in twisted bilayer graphene

We theoretically study the components of the dynamical optical conductivity tensor and associated finite -frequency dielectric response of bilayer graphene (BLG), where one graphene layer can slide in -plane or commensurably twist on top of the other. Our results reveal that even slight deviations from the conventional AA, AB, or AC stacking orders yield a finite transverse conductivity. Upon calculating the optical conductivity of the BLG at any arbitrary interlayer displacement, increment , and chemical potential, mu, it is utilized for a layered device with an epsilon -near -zero (ENZ) insert and metallic back plate. We find that both increment and mu can effectively control the polarization, energy flow direction, and absorptivity of linearly polarized incident light. By appropriately tailoring increment and mu, near -perfect absorption and tunable dissipation can be accessible through particular angles of incidence and a broad range of ENZ layer thicknesses. Our findings can be applied to the design of programmable optoelectronics devices.