Electronic Metamaterials with Tunable Second-order Optical Nonlinearities

摘要

The ability to engineer metamaterials with tunable nonlinear opticalproperties is crucial for nonlinear optics. Traditionally, metals have beenemployed to enhance nonlinear optical interactions through field localization.Here, inspired by the electronic properties of materials, we introduce anddemonstrate experimentally an asymmetric metal-semiconductor-metal (MSM)metamaterial that exhibits a large and electronically tunable effectivesecond-order optical susceptibility (\c{hi}(2)). The induced \c{hi}(2)originates from the interaction between the third-order optical susceptibilityof the semiconductor (\c{hi}(3)) with the engineered internal electric fieldresulting from the two metals with dissimilar work function at its interfaces.We demonstrate a five times larger second-harmonic intensity from the MSMmetamaterial, compared to contributions from its constituents with electricallytunable nonlinear coefficient ranging from 2.8 to 15.6 pm/V.