Graphene induced spectral tuning of metamaterial absorbers at mid-infrared frequencies

In order to expand bandwidth of the resonant metamaterial absorbers, we investigate their spectral tuning at mid-infrared frequencies using graphene. We consider the absorbers with square metallic patches, cross-shaped resonators, and split ring resonators. Their resonances can be blue shifted by increasing graphene conductivity. Among these structures, split ring resonators produce the largest electric fields enabling huge spectral shifts, almost 30%. In addition, the tuning can be used for switching the mid-infrared waves at the absorber resonance. Here, the reflectance is zero, so even a small spectral shift of the resonance results in a huge increase of the reflectance. (C) 2013 AIP Publishing LLC.