Tunable resonant graphene plasmons for mid-infrared biosensing

Tunable resonant surface plasmons (SPs) based on graphene nanoribbon are studied to detect nanoscale protein molecules in mid-infrared (mid-IR) region. The two-dimensional nature of the collective oscillations of Dirac quasi-particles result in a strong electric field confinement of graphene plasmons, and lead to a large light overlap with the nanoscale biomolecules, which plays an essential role in the demonstrated high sensitivity in the detection of the refractive index of the nanometric-scale targeted protein molecule. Furthermore, Fermi level controlled resonant SPs in graphene nanostructure provide a unique capacity to control light in nanoscale to probe the protein chemical vibrations. Tunable resonant spectra selectivity combined with the super ambient condition sensitivity promise the graphene plasmons based device exciting prospects in future nanoscale biosensing. (C) 2016 Optical Society of America