Generation of third harmonic of terahertz waves by a nonlinear graphene multilayer metasurface

Nonlinear diffraction of a plane electromagnetic wave from multilayer nonlinear metasurfaces consisting of double-period lattices of rectangular finite-length graphene ribbons on dielectric spacer layers is investigated in the terahertz (THz) frequency range. An increase in the third-harmonic generation efficiency by several orders of magnitude at the surface plasmon–polariton resonance frequencies is demonstrated. It is demonstrated that the third-harmonic frequency can be controlled by dynamic tuning of chemical potential without changing geometry or dimensions of the graphene metasurface.