Design of graphene terahertz reflectarray based on boron nitride substrate

The unique electronic band structure of graphene leads to complex surface conductivity at THz frequencies, which allows the propagation of very slow plasmonic modes. This leads to a drastically reduced electrical size of the array unit cell and thereby reconfigurable performance. In our lab, we have already developed the reflectarray element based on silicon dioxide substrate. Since the surface of silicon dioxide is very rough, the extraordinary properties of graphene is damaged when coating the silicon dioxide with graphene. Thus, we propose a design of graphene reflective cell based on boron nitride substrate at terahertz in this paper. Ansoft HFSS software is used to simulate and optimize the proposed structure. Fig.2 shows the simulated reflection coefficients of the graphene reflective cell as a function of graphene patch size and chemical potential. It is seen that a full range of 0°~360° can be successfully realized for the reflection phase at 1.5 THz. Besides, the reflectarray is realized with the graphene reflective cells that are properly sized, arranged, and biased. This method can satisfy the required reflection coefficients and provide the possibility for the realization of the beam scanning characteristic.