Triple-band tunable terahertz perfect absorber based on graphene metamaterial

To further reduce the structural complexity of high-performance modulation devices in the terahertz region, we propose and demonstrate a triple-band tunable metamaterial perfect absorber, which consists of a patterned graphene and Au ground plane spaced by Si dielectric layer. The graphene surface plasmon resonance at the terahertz region is used to couple the patterned graphene with the electric field and provide electric dipole resonance to form multiple absorption peaks. Numerical results indicate that the amplitude of the absorption peaks is large than 99.9% at 0.489 THz, 1.492 THz, and 2.437 THz, respectively. In addition, due to the amplitude of the absorption peaks that can be controlled by the Fermi level via externally applied bias voltage, it means that we are able to switch the structure between reflector and absorber at their corresponding absorption bands. However, the symmetric unit cell structure of the proposed absorber is the inherent reason for the excellent polarization-insensitive, and the broadband absorption of the absorber maintains excellent absorption performance over a wide range of incident angles. Therefore, the designed graphene-based terahertz metamaterial function device has great potential in modulation and sensing.