# Large enhancement of the effective second-order nonlinearity in graphene metasurfaces

## TL;DR

This paper demonstrates that double-resonant plasmon excitation in graphene metasurfaces can significantly enhance their effective second-order nonlinearity, enabling advanced active nanodevices.

## Contribution

It introduces a homogenization technique to accurately predict nonlinear responses and shows a three-order magnitude enhancement of second-order susceptibility in graphene metasurfaces.

## Key findings

- Effective second-order susceptibility enhanced by over 1000 times.
- Homogenization predictions agree well with numerical solutions.
- Potential for developing new active nanodevices with graphene structures.

## Abstract

Using a powerful homogenization technique, one- and two-dimensional graphene metasurfaces are homogenized both at the fundamental frequency (FF) and second harmonic (SH). In both cases, there is excellent agreement between the predictions of the homogenization method and those based on rigorous numerical solutions of Maxwell equations. The homogenization technique is then employed to demonstrate that, owing to a double-resonant plasmon excitation mechanism that leads to strong, simultaneous field enhancement at the FF and SH, the effective second-order susceptibility of graphene metasurfaces can be enhanced by more than three orders of magnitude as compared to the intrinsic second-order susceptibility of a graphene sheet placed on the same substrate. In addition, we explore the implications of our results on the development of new active nanodevices that incorporate nanopatterned graphene structures.