In this paper, we report on the preparation of graphene oxide and graphene oxide-Au nanodispersions in various solvents, such as water, DMF (N,N-dimethylformamide) and NMP (N-methyl-2-pyrrolidone). Optical, structural and nonlinear optical properties of all the samples have been studied. The nonlinear optical properties have been measured using the z-scan technique. It is shown that the incorporation of Au nanoparticles can greatly improve the nonlinear optical properties of graphene oxide. More importantly, the fact is recognized that the media that surround the nonlinear sample can influence its nonlinear optical properties by their nonlocal action. The nonlocal z-scan theory has been used to estimate the role of the surrounding medium in changing the samples' nonlinear responses
