Electro-optically Modulated Nonlinear Metasurfaces.

Electrically reconfigurable nonlinear metasurfaces provide dynamic control over nonlinear phenomena such as second-harmonic generation (SHG), unlocking novel applications in signal processing, light switching, and sensing. Previous methods, like electric-field-induced SHG in plasmonic metasurfaces and Stark-tuned nonlinearities in quantum well metasurfaces, face limitations due to weak SHG responses from metals and mid-infrared constraints of quantum wells, respectively. Addressing the need for efficient SHG control in the visible and near-infrared ranges, we present a novel approach using the electro-optic (EO) effect to modulate SHG. By leveraging the exceptional EO and SHG properties of lithium niobate (LN), we integrate the EO effect with SHG within a metasurface framework for the first time. Our LN metasurface achieves an 11.3% modulation depth in SHG amplitude under a ±50 V alternating voltage. These results open new avenues for reconfigurable photonic applications. including tunable nonlinear light sources, quantum optics, and nonlinear information processing.