Multi-band perfect absorber based on graphene monolayer coupled to photonic nanostructure

Abstract

An active plasmonic device is designed to support multiple perfect absorption peaks using the highly confined graphene surface plasmons excited by silicon-based diffractive gratings. The physical origination corresponding to different absorption peaks is analyzed and the principle of impedance matching is used to explain perfect absorption. We show that the absorption spectrum is effectively controllable over a wide wavelength range by changing the Fermi levels, relaxation time of the graphene and geometric parameters of the device. This study could provide some possibility facilitating the design of next generation optical and photoelectronic structure by combining graphene and dielectric grating.

A multi-dimensional photodetector based on an α-MoO3 grating and graphene

“…The conductivity of graphene can be characterized by contributions from both interband and intraband transitions: 36–38 σ s = σ intra s + σ inter s ,where T is the temperature, e is the elementary charge, ħ represents the reduced Planck constant, τ is the relaxation time, E F is the Fermi energy, and ω represents the angular frequency. In the calculation, the conductivity of graphene can be simply expressed by the Drude equation: 39–42 where μ is the carrier mobility of graphene, V F = 10 6 m s −1 represents the Fermi velocity. The graphene conductivity at different Fermi energies is demonstrated as in Fig.…”

“…is the temperature, e is the elementary charge, h represents the reduced Planck constant, t is the relaxation time, E F is the Fermi energy, and o represents the angular frequency. In the calculation, the conductivity of graphene can be simply expressed by the Drude equation: [39][40][41][42]…”