Giant enhancement of third-harmonic generation in graphene-metal heterostructures

TL;DR

This paper demonstrates a three-orders-of-magnitude enhancement in third-harmonic generation in graphene-insulator-metal heterostructures, showing their potential for tunable nano-optoelectronic devices.

Contribution

It reveals the significant nonlinear optical enhancement in graphene heterostructures and the role of graphene plasmons in mediating this nonlinearity.

Findings

Third-harmonic signal enhanced by three orders of magnitude.

Graphene plasmons mediate and modify the nonlinear response.

Electrical tuning of nonlinearity via Fermi energy adjustment.

Abstract

Nonlinear nanophotonics leverages engineered nanostructures to funnel light into small volumes and intensify nonlinear optical processes with spectral and spatial control. Due to its intrinsically large and electrically tunable nonlinear optical response, graphene is an especially promising nanomaterial for nonlinear optoelectronic applications. Here we report on exceptionally strong optical nonlinearities in graphene-insulator-metal heterostructures, demonstrating an enhancement by three orders of magnitude in the third-harmonic signal compared to bare graphene. Furthermore, by increasing the graphene Fermi energy through an external gate voltage, we find that graphene plasmons mediate the optical nonlinearity and modify the third-harmonic signal. Our findings show that graphene-insulator-metal is a promising heterostructure for optically-controlled and electrically-tunable nano-optoelectronic components.