Nanostructure for near total light absorption in a monolayer of graphene in the visible

We propose a highly compact structure for near total light absorption in a monolayer of graphene in the visible. The structure consists of a grating slab covered with the graphene monolayer. The grating slab is separated from a metallic back reflector by a dielectric spacer. The structure supports a guided resonance in the visible. We show that such a structure enhances light-matter interactions in graphene via critical coupling by matching the external leakage rate of the guided resonance and the intrinsic loss rate in the system. We also show that, by using the dielectric spacer between the grating and the metallic mirror, near total absorption in the graphene monolayer can be achieved in the visible without the need for thick multilayer dielectric mirrors. The proposed structure could find applications in the design of efficient nanoscale visible-light photodetectors and modulators. (C) 2018 Optical Society of America