Plasmonic metasurfaces: From perfect absorption to phase modulation

Metasurfaces in metal/insulator/metal configuration have recently been widely used in photonics research, with applications ranging from perfect absorption to phase modulation but why and when such structures can realize what kinds of functionalities are not fully understood. Here, based on coupled-model analysis, we establish a complete phase diagram for such systems, in which their optical properties are fully controlled by two simple parameters (the intrinsic and radiation losses), which are in turn, intimately related to the geometrical/material parameters of the underlying structure. These results can guide one to design appropriate metasurfaces with tailored functionalities (e.g., perfect absorption, phase modulator, electric/magnetic reflector, etc.), which are demonstrated by our experiments and simulations in the Terahertz regime.