  In this paper, we proposed a theoretical model in the far-infrared and
terahertz (THz) bands, which is a dumbbell-shaped graphene metamaterial arrays
with a combination of graphene nanorod and two semisphere-suspended heads. We
report a detailed theoretical investigation on how to enhance localized
electric field and the absorption in the dumbbell-shaped graphene metamaterial
arrays. The simulation results show that by changing the geometrical parameters
of the structure and the Fermi level of graphene, we can change the absorption
characteristics. Furthermore, we have discovered that the resonant wavelength
is insensitive to TM polarization. In addition, we also find that the
double-layer graphene arrays have better absorption characteristics than
single-layer graphene arrays. This work allows us to achieve tunable terahertz
absorber, and may also provide potential applications in optical filter and
biochemical sensing.
