Graphene(s): Tuning their Nonlinear Optical Response

Abstract

Graphene and graphene derivatives are among the most studied members of the family of two-dimensional (2D) materials, their physical and chemical properties having been the object of numerous and extensive investigations during the last few years. Their one atom-thick two-dimensional geometry has important consequences on their electronic bands' formation, giving rise to a unique conical-like band structure, converging to a single (Dirac) point, resulting to electrons exhibiting some exotic and unprecedented properties (as e.g. electrons moving with relativistic speed, huge absorption of ~2.3% per one-atom thick layer, flat and unstructured UV-Vis-NIR absorption spectrum implying that optical excitations anywhere from the UV to IR are of resonant character, etc.).In the present work, recent results will be presented concerning the nonlinear optical (NLO) response of some graphene oxide(s) and graphene fluoride(s) having different degrees of oxidation and fluorination respectively and consisting of different number of graphenic layers. In particular, their nonlinear optical properties (i.e. nonlinear absorption coefficient β, nonlinear refractive index parameter γ' and third-order nonlinear susceptibility X <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> as determined under nanosecond and picosecond laser excitations will be presented and discussed in detail. The present results can shed more light on the NLO response of graphene derivatives and the operational physical mechanisms while they can provide a guide for the efficient tuning of the NLO properties in view of specific applications in photonics and optoelectronics.