Electronic Metamaterials with Tunable Second-order Optical Nonlinearities

TL;DR

This paper introduces an asymmetric metal-semiconductor-metal metamaterial with electronically tunable second-order nonlinearities, achieving significantly enhanced second-harmonic generation through engineered internal electric fields.

Contribution

It presents the first experimental demonstration of a tunable second-order optical susceptibility in MSM metamaterials driven by internal electric fields from dissimilar metal interfaces.

Findings

Five times larger second-harmonic intensity compared to constituents.

Electrically tunable nonlinear coefficient from 2.8 to 15.6 pm/V.

Large, tunable second-order nonlinearities achieved.

Abstract

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