Hollow-petal graphene metasurface for broadband tunable THz absorption.

We propose a tunable and broadband terahertz (THz)-wave absorber based on the graphene metasurface, which consists of a layer of graphene-hollow-petal structure array and a bottom copper film separated by a 20-μm-thick lossless thermo plastic olefin polymer of amorphous structure layer. The mechanism of such a THz-wave absorber is numerically investigated and theoretically analyzed with the aid of a modified Fabry-Perot resonant model and finite element method. A large absorption efficiency of more than 90% in a frequency range of 2.66 THz ∼3.46  THz was obtained up to a THz-wave incident angle as large as 50°. The absorption bandwidth and absorptivity can be tuned by changing the bias voltage of the graphene metasurface Fermi level. This work indicates that our device has potential applications with respect to tunable sensors and smart absorbers.