New J. Phys. 16, 053014 (2014)

With its strong optical coupling, broadband absorption and electronic properties, graphene is a natural candidate for use in optically controlled devices in photonics. However, its nonlinear optical properties have not been fully investigated. Now, Jin Luo Cheng and co-workers from the University of Toronto and Vrije Universiteit Brussel have theoretically investigated the linear and third-order nonlinear optical conductivity of doped graphene and conducted calculations for third-harmonic generation, the Kerr effect and parametric frequency conversion. The researchers performed zero-temperature perturbative calculations for the tight-binding model. They fully accounted for both the interband and intraband motion of the electrons, which were perturbed by an incident field. They obtained a formula that exhibits divergences resulting from resonances between the photon energy and the chemical potential. The results obtained varied greatly for different frequency combinations. The researchers state that, “combined with the tunability of the chemical potential by an external gate voltage or chemical doping this should lead to novel approaches for controlling the nonlinear optical properties of graphene.”