Perspectives on nonlinear optics of graphene: Opportunities and challenges

The first nonlinear-optical experiments with graphene date back over a decade, and a wide range of research breakthroughs has been reported since then, particularly on the third-order nonlinearities of the material. Graphene has been shown to exhibit extraordinary saturable absorption properties as well as extremely strong nonlinear refraction effects, both of which hold promise for practical use in nonlinear-optical devices. In this Perspective, after providing a very brief overview of the state of the art, I elaborate on the most relevant material parameters for future research and development activities in this domain, while also highlighting specifi features of graphene’s linear and nonlinear-optical properties that are sometimes overlooked in experiments. Finally, I present my view on what the opportunities and remaining challenges are in the practical exploitation of graphene for nonlinear-optical applications.