Enhancing terahertz wave modulation by metallic structures in optical pumped graphene layer

The terahertz (THz) wave modulation in graphene with the metallic structure and optical pump is analyzed theoretically and experimentally in this paper. The modulation depth is enhanced with the combination of optical pump and metallic structure localization. The subwavelength metallic structure enhances the interaction between the THz wave and graphene with the excitation of the extraordinary transmission resonant. The optical pump of continuous waved (CW) laser provides an enhanced interact electric field on the surface of graphene. The tuning range of the Fermi level of the graphene is enhanced by optical pump on the basis of modulation voltage. The maximum amplitude modulation depth of 54% is achieved by changing the modulation voltage from -25 V to +25 V. The behavior of the modulation enhancement provides a candidate for improving the performance of graphene based THz modulator. •Combine metallic subwavelength structure and CW laser pump, enhance THz wave modulation depth.•Metallic subwavelength structure localization, enhance THz wave interact with graphene.•CW laser pump raise carrier density, further enhance THz wave modulation depth.