Dynamically tunable terahertz metamaterial sensor based on metal–graphene hybrid structural unit

By verifying the electromagnetic response characteristics of graphene in the low terahertz (THz) band, a terahertz metamaterial sensor is proposed. The unit cell of the metamaterial sensor is a split ring resonator nested square ring resonator. The split ring resonator with four gaps is made of lossy metal, and the square ring resonator is formed by graphene. This structure can produce two high-performance resonant valleys in the transmission spectrum of 0.1–1.9 THz. The quantum interference between metal–graphene hybrid units also produces a reverse electromagnetically induced transparency (EIT)-like resonant peak between the two resonant valleys. Compared with the bimetallic ring resonator having the same shape and size, the sensor can dynamically adjust the position of the lower frequency resonant valley, thus, realizing the active tuning of the bandwidth and amplitude of the EIT-like resonant peak. The results demonstrate that the proposed sensor has a better sensing performance and can improve the detection precision by tuning itself to avoid the interference of environmental factors and the properties of samples. Combined with the advantages of convenience, rapidity, and non-damage of terahertz spectrum detection, the sensor has a good application potential to improve the unlabeled trace matter detection.