Tunable plasmon-induced transparency and its slow light performance based on terahertz metamaterials

A double hexagonal single ‘S’ metamaterial (DHSSM), exhibiting plasmon-induced transparency (PIT) in its spectral response is studied in this paper. Amplitude modulation of the PIT window is achieved by varying the azimuth angle of substructure ‘S’. Theoretical investigations into the PIT effect are conducted through numerical simulations. Moreover, an equivalent coupling circuit and Lorentz model are constructed to elucidate the PIT modulation mechanism. The results reveal that the PIT physical mechanism of the DHSSM has originated in destructive interference between bright-bright modes, which is directly excited by terahertz waves on the double hexagonal split rings and the ‘S’ substructure. For slow optical propagation performance, the structure has a high group delay (up to 41.92 ps) while allowing for the adjustment of the transparency window amplitude. The proposed metamaterial holds promising prospects for applications in slow light devices, switches, and filters within the terahertz frequency range.