Enhanced optical Kerr effect method for a detailed characterization of the third order nonlinearity of 2D materials applied to graphene

TL;DR

This paper introduces an enhanced optical Kerr effect method combined with a theoretical model to precisely characterize the third-order nonlinear optical response of graphene, including tensor components and substrate effects.

Contribution

The study presents a novel, highly sensitive method for measuring third-order nonlinearities in 2D materials, validated on graphene, with potential applications to other similar materials.

Findings

Separated the time response of tensor components of nonlinear susceptibility.

Confirmed that out-of-plane tensor components are negligible.

Quantified substrate effects on nonlinear coefficients.

Abstract

Using an enhanced optically heterodyned optical Kerr effect method and a theoretical description of the interactions between an optical beam, a single layer of graphene, and its substrate, we provide experimental answers to questions raised by theoretical models of graphene third-order nonlinear optical response. In particular, we measure separately the time response of the two main tensor components of the nonlinear susceptibility, we validate the assumption that the out-of plane tensor components are small, and we quantify the optical impact of the substrate on the measured coefficients. Our method can be applied to other 2D materials, as it relies mainly on the small ratio between the thickness and the wavelength.