Active dual-band terahertz surface plasmonic wave excitation using graphene metasurfaces

The active control of surface plasmonic waves (SPWs) through metasurfaces holds significant potential for advancing on-chip optical components. However, recent research has primarily concentrated on actively modulating the propagation and coupling of SPWs at a single frequency. Here, we propose a dual-band SPW excitation strategy in the terahertz regime using two sets of orthogonally arranged metallic slit arrays based on electromagnetically induced transparency (EIT) coupling, which enables SPW excitations at two separate frequencies under orthogonal polarization incidences. Moreover, by placing graphene ribbons on top of the arrays to adjust the damping of dark mode resonance through capacitive coupling, we numerically demonstrate an active dual-band SPWs coupler with a high modulation depth achieving 86%. Our method is universal and has application prospects in future versatile integrated photonic devices, including data interaction and frequency division multiplexing.