▎ 摘　　要

We have numerically demonstrated a tunable broadband metamaterial absorber (MA) by introducing a graphene pattern and a gold disk, of which the bandwidth is up to 3.4 THz. When the chemical potential of graphene changes from 0 eV to 0.5 eV, the proposed MA structure can also be used as a modulator with the minimum and maximum modulate depth being about 69.5% and 92.5%, respectively. By tuning the relaxation time of the graphene from 0.1 ps to 0.5 ps, several obvious absorption peaks will occur in the broad and flat absorption band, which will deteriorate the broadband absorption characteristics and make it show a trend of multi-band absorption characteristics. To further increase the absorption bandwidth, a new graphene pattern and an additional gold disk are added into the proposed MA structure to form a new type of MA structure. Simulation result shows that the newly designed MA structure can achieve a wider absorption bandwidth of more than 4.0 THz. Meanwhile, it still has the performance of excellent modulation characteristic, polarization insensitive and wide tolerance of incident angles. All these optimal characteristics of the proposed MA structures will undoubtedly benefit the use of metamaterial absorber, high speed communication, terahertz detection devices, optoelectronic devices and so on.