  We present a dynamically frequency tunable Fano resonance planar device
composed of periodically asymmetric graphene nanodisk pair for the mid-infrared
region. There are two kinds of modes in this structure, that is, the symmetric
mode and the antisymmetric mode. The resonance coupling between the symmetric
and antisymmetric modes creates a classical Fano resonance. Both of the Fano
resonance amplitude and frequency of the structure can be dynamically
controlled by varying the Fermi energy of graphene. Resonance transition in the
structure is studied to reveal the physical mechanism behind the dynamically
tunable Fano resonance. The features of the Fano resonant graphene
nanostructures should have promising applications in tunable THz filters,
switches, and modulators.
