A tunable multi-band terahertz sensor based on graphene metamaterial

A high-sensitivity, adjustable multi-band terahertz sensor built on graphene-based metamaterials is proposed in this study. The device is composed of a two-dimensional patterned graphene sheet, a polyimide dielectric film, and a metal substrate. Its photonic properties in the terahertz range are simulated and analyzed via the finite difference time domain method. The findings revealed that the sensor can generate three absorption peaks with absorption coefficients of 71.9%, 99.9%, and 99.6%, respectively. The influence of the parameters of the graphene pattern and the thickness of the polyimide dielectric layer on the absorption performance is explored, and the optimal structural parameters of the sensor are obtained. The polarization angle of the incident light and the Fermi energy level of graphene are also investigated. The sensor is found to have the advantages of polarization insensitivity and dynamic tunability. In order to further evaluate the sensing performance, the spectrum is examined by applying various analytes to the device. The sensor yielded a maximum sensitivity of 1.02 THz/RIU, alongside a peak Q-factor of 58.73 and an optimal figure of merit of 9.76. The results of this study will provide new insights for the metamaterial sensors, which are multi-band, tunable, insensitive to large-angle oblique incidence, and polarization-independent.