Frequency-tunable terahertz angular selectivity based on a dielectric-graphene multilayer structure

To achieve frequency-tunable angular selectivity at terahertz frequencies, a tunable epsilon-near-zero (ENZ) metamaterial based on a subwavelength dielectric-graphene multilayer structure is designed. The ENZ frequency of the dielectric-graphene multilayer can be dynamically tuned by the gate voltage applied to graphene. Transmittance angular spectra show that only the incident lights close to normal incidence can propagate through the structure while other incident lights cannot , which indicates that our structure can be utilized for frequency-tunable terahertz angular selection. The optimal directivity D reaches 183 and the transmittance at normal incidence reaches 0.462. This multilayer-based tunable terahertz ENZ metamaterial will possess potential application prospects in tunable highly directive antennas.