Polarization and angle insensitive electromagnetic-induced transparency based on circular graphene metamaterial

Abstract In this manuscript, a metamaterial consisting of the central graphene disk and the graphene circular hole is investigated to achieve polarization and angle insensitive electromagnetic induced transparency (EIT) effect. When linearly polarized light with different polarization directions, left circularly polarized light (LCP), and right circularly polarized light (RCP) in the terahertz band are incident, the metamaterial structure, due to its symmetry, exhibits excellent polarization insensitivity with a transmission peak exceeding 93.5% at 5.21 THz. Moreover, it shows excellent angle insensitivity, maintaining a transmission peak intensity above 80% for incident angles up to 60°. The EIT-like effect arises from destructive interference between two bright modes. The dynamic tunability of graphene allows for simultaneous regulation of the transparent window and refractive index sensitivity. As the Fermi energy level increases from 0.4 eV to 0.7 eV, the transparency peak frequency shifts from 4.68 THz to 6.16 THz. The slow-light effect near the transmission window offers new insights for designing high-performance slow light devices. Additionally, as the external refractive index increases from 1 to 1.3, the transmission spectrum of the metamaterial exhibits a significant redshift, making it a promising candidate for sensing applications. Overall, the proposed metamaterial shows great potential for use in multifunctional terahertz devices.