▎ 摘　　要

The graphene based metal-insulator-metal (MIM) metamaterial is numerically investigated to realize an active and adjustable multi-band perfect absorber, which is composed of an asymmetric double T-shaped cavity on the top layer. As the symmetry of T-shaped cavities is broken, the previous dual-band absorption will be converted to tri-band absorber. The corresponding electric field distribution at each resonant position is invesitgated to figure out the physical mechanism. More interestingly, these resonant peaks will split into multiband with further destruction of the central symmetry. In addition, non-contact dynamic control of perfect absorption is explored by tuning the Fermi energy, the polarization angle and the incident angle. Finally, the sensitivity of our proposed design is elaborately examined with different concentrations of CS2 dropped into the cavities. The results demonstrate that the refraction index per unit can reach up to a high value of 1673.33 nm/RIU. Therefore, this work delivers a new strategy to design tunable multi-band absorbers and has potential applications in highly tunable optical switchers, sensors and filters.