Electrical control of a THz beam generated through nonlinear metasurfaces based on multiple quantum wells

A plasmonic-type nonlinear metasurface loaded with Multiple Quantum Well (MQW) is studied for terahertz beam generation through the difference frequency generation (DFG) phenomenon. We calculate the second-order nonlinear susceptibility coefficient of MQW. Furthermore, we investigate the effect of applying a bias voltage across the MQW on the magnitude and phase of the second-order nonlinear susceptibility coefficient. Finally, electrical steering of THz beam is demonstrated through the effective medium theory and free-space Green's function.