Design of absorber and refractive index sensor structure based on graphene metamaterials at terahertz frequencies

In this article, a refractive index absorber and sensor based on graphene metamaterials in the terahertz range is presented. In many studies, the dependence of the sensor on the radiation angle and polarization type has not been investigated, and usually complex structures have been used, the reason for this complexity is the lack of a systematic method and the reader is not convinced by the reasons of the geometry of the structure in the desired frequency band. In this article, advanced transmission line theory has been used to investigate the geometric structure and efficiency of terahertz sensors.The designed sensor has an alternating arrangement of graphene discs on a dielectric material and an integrated gold plate on the other side, which compared to other references has high accuracy in the selection of parameters and the geometry of its structure without the use of optimization algorithms has been calculated. The values maximum figure of merit (FOM) 24.5, the quality factor (Q-Factor) 80 and the sensitivity 1.57 THz⁄RIU have been obtained, which has improved significantly compared to previous works. Also, the simplicity of the structure, reduction of calculation time and memory, higher sensitivity and better stability are the advantages of this design compared to the previous methods.