Strong tunable absorption enhancement in graphene using dielectric-metal core-shell resonators

We theoretically investigate light absorption by a graphene monolayer that is coated on the outside of dielectric-metal core-shell resonators (DMCSRs). We demonstrate that light absorption of graphene can be greatly enhanced in such multi-layered core-shell architectures as a result of the excitation of the hybridized bonding plasmon resonance supported by the DMCSRs. We also demonstrate that the absorption enhancement in graphene can be easily tuned over a wide range from the visible to the near-infrared, and particularly the enhancement factor can be optimally maximized at any selective wavelength, by simultaneously varying the dielectric core size and the metal shell thickness. Our results suggest that the graphene-wrapped DMCSRs with strong and highly wavelength-tunable absorption enhancement in graphene could be attractive candidates for applications in graphene-based photodetectors and image sensors.