Enhanced absorption of graphene in the visible region by use of plasmonic nanostructures

Low absorption of graphene in the visible range of the spectrum makes it difficult to uniquely benefit from this material in ultra-fast optoelectronic applications. We numerically propose to utilize patterned metallic nanostructures to increase light absorption in single-layer graphene. Simulation results show that excitation of surface plasmon resonances in the metallic nanostructures significantly enhances the local electromagnetic field near the graphene layer, therefore leading to a dramatic enhancement of the absorption in the graphene layer itself. Broadband high optical absorption can be realized by engineering the metal nanostructures, while maintaining insensitivity to the incident angle. Our results pave a new and promising way to enhance visible-light absorption in the graphene layer, which is potentially interesting for graphene-based photovoltaics.