Triple plasmon-induced transparency and polarization-insensitive optical switch based on monolayer patterned graphene metamaterial

This study introduces a single-layer patterned graphene metamaterial, composed of a graphene ring (GR), two parallel graphene strips (TPGSs), two vertical graphene strips (TVGSs), and a graphene block (GB), which achieves triple plasmon-induced transparency (TPIT) in the terahertz (THz) frequency range using coupled mode theory (CMT) and the finite-difference time-domain (FDTD) technique. Moreover, a synchronized electro-optical switch with four modulation modes is implemented by dynamically adjusting graphene's Fermi level, exhibiting modulation degrees of amplitude (MDA) of 88.3%, 94.7%, 86.9%, and 89.0% at 1.69THz, 3.14THz, 3.95THz, and 4.67THz, respectively. In addition, the modes excited by TPGSs and TVGSs interconvert due to the proposed structure's symmetry, accounting for the polarization insensitivity of TPIT. The enhanced MDA and polarization insensitivity of the electro-optical switch presented in this study significantly surpass those of comparable electro-optical switches. As a result, the polarization insensitivity of multiple optical switches to incident light fields offers a promising approach for designing optoelectronic devices.