Resonance enhanced absorption in a graphene monolayer using deep metal gratings

It has been demonstrated recently that metal gratings can significantly improve the near-infrared absorptance of graphene from 0.023 to nearly 0.70 because of the excitation of magnetic polaritons (MPs). In the present study, it is shown that the absorptance of graphene can be further enhanced to more than 0.80 by surface plasmon polaritons (SPPs) enabled by the grating. Meanwhile, graphene behaves as a sheet resistor that is able to boost the absorption when MPs or SPPs are excited without changing their resonance frequencies or dispersion relations. The effects of higher-order MPs, as well as the grating geometry on the enhanced absorptance, are also examined. Rigorous coupled-wave analysis (RCWA) is employed to calculate the radiative properties and power dissipation density in both the graphene and the metal grating. This study will facilitate the understanding of the coupling phenomena between graphene and nanostructures and may also benefit the design of next-generation graphenebased optical and optoelectronic devices. (C) 2015 Optical Society of America