Terahertz Generation from Plasmonic Metasurfaces

We numerically report a novel THz generation method based on plasmonic metasurface consist of single layer split-ring resonators array. The terahertz generation originates from nonlinear optical rectification in meta-atoms is broadband and free from phase match conditions. The strong linear response and inherent nonlinear behaviors in plasmonic metasurface can be described by a time-domain hydrodynamic model, in which both surface and bulk contributions of nonlinearity are considered. The coupled Maxwell-hydrodynamic system capturing full-wave physics and free electron dynamics is solved with a parallel finite-difference time-domain (FDTD) method. The proposed method is fundamentally important to design nonlinear plasmonic nanodevices, especially for efficient and broadband THz emitters.