Enhanced absorption of long-wave infrared light from silicon microholes array by filling in its gaps with graphene film

As an exciting material for its excellent electrical and optical properties , graphene is widely used in optoelectronics currently. In this work, the absorption of long-wave infrared light from silicon microholes (Si-MHs) array, in the gaps of which both graphene and metal films are filled in to form as the active layers , is simulated with finite-difference time-domain (FDTD) method by considering the anisotropic properties of graphene. Our simulations show the position and the intensity of the absorption peaks can be linearly modulated by the quadrate Si-MHs' diameter within a certain range. The absorption of the Si-MHs array with a hybrid graphene (350 nm)/Au (50 nm)/graphene (350 nm) film can reach close to 100 %. Also, the absorption properties of the hybrid graphene/metal/graphene film integrated into Si-MH array demonstrate negligible variation with any metal such as Au, Ag, Al and Cu. Further, our simulation is confirmed by the reports published previously. Thus, it provides a novel method for long-wave infrared optoelectronics . • Light trapping effect of silicon microholes array is optimized. • Anisotropic property of graphene is considered for simulation. • Metals-induced surface plasmon is introduced for light absorption enhancement. • Guided-mode resonance effect can be used to modulate the absorption peak. • The relation between anisotropy of graphene and high absorption is revealed.