Absorption enhancement in tunable graphene based plasmonic absorber

In this work, a graphene based plasmonic absorber with two absorption peaks of 0.99 and a wide full width at half maximum (FWHM) between the wavelengths of 1455 and 1610 nm is presented. The proposed absorber is composed of a single layer of graphene that covers the nanostructure with an array of ring and L-shaped grooves on a metal film. The light absorption is more due to the localized surface plasmons (LSPs) resonance in the grooves that reinforces the interaction of light and graphene. Therefore, the absorption of the structure is enhanced. We have shown that the absorber can be tuned by variation of the L-shaped arms length and grooves depth. Moreover, it is possible to create three absorption peaks and have a triple-band absorber in the near-infrared region.