Electrically-modulated infrared absorption of graphene metamaterials via magnetic dipole resonance

Abstract

To increase the absorption efficiency of graphene-based devices, we propose a metamaterial structure comprising of a square metal plate array on graphene, a dielectric spacer, and a metal substrate. This work numerically demonstrates enhancement of the near-infrared absorption of monolayer graphene via the magnetic dipole resonance in the metamaterial under normal-incidence. Furthermore, the absorption efficiency of graphene-based devices can reach up to 96% with proposed structures incorporating three layers of graphene when the Fermi energy is 0.6 eV. Varying the Fermi energy by varying the applied voltage, is shown to enable an increase of the absorption efficiency of graphene-based devices with a reduction of the Fermi energy. Therefore, the absorption wavelength exhibits a linear electrical modulation in a wide range from 1362 to 1787 nm. The designed graphene light absorber has potential applications in optoelectronic devices such as photodetectors and perfect absorbers. • A new resonance peak appeared by adding single layer graphene. • By increasing the number of graphene layers to three, the absorption efficiency can be increased from 32% to 96%. • By changing the Fermi energy of graphene, the maximum tunable wavelength range can reach 425 nm. • The absorption efficiency of all resonance peaks is more than 87%.