▎ 摘　　要

A dual-channel narrowband polarization independent terahertz absorber based on graphene-silica raised ring has been proposed and investigated in this paper. The absorber obtains two narrowband near-unit absorption peaks at 2.44 THz and 5.56 THz. It was found that cascading structures and changing the shape of the dielectric layer facilitated the formation of more and narrower absorptions. The physical mechanism of these two structures at the resonant position is verified and explained using impedance matching and electromagnetic field distribution. Simulation results show that the absorber is insensitive to the polarization angle in TE and TM modes due to rotational symmetry. When it is used as a sensor device, its maximum Q value is 101.5 and its maximum sensitivity is 1.04 THz/ RIU. In addition, a third near-unit narrowband absorption at 8.37 THz can be obtained by cascading a SiO2 disks. The simulation results show that the first two absorption peaks are independently tunable with respect to the third one when changing the chemical potential of graphene. Meanwhile, the resonant frequency of the third peak can be adjusted independently by adjusting the radius of the SiO2 disk. Therefore, the absorber designed in this paper is promising for applications in frequency selectors, sensors, filters, etc.