Nonlinear optical properties of the mixture of ZnO nanoparticles and graphene nanosheets

In this work, the experimental investigation of the nonlinear response of the mixture of ZnO nanoparticles and graphene nanosheets as a function of volumetric ratio of ZnO and graphene colloidal suspensions has been reported. The colloidal ZnO nanoparticle and graphene were synthesized by nanosecond pulsed laser ablation of Zn and graphite target in water, respectively. The X-ray diffraction pattern, transmission electron microscopy, Raman spectrum and linear absorption properties of ZnO nanoparticle and graphene nanosheets were used to characterize the ablation products. D band and G band of Raman shift at 1325 and 1580 cm(-1), respectively, confirmed the formation of graphene nanosheets in water. Results show that the bandgap energy of mixtures decreased noticeably with increasing the amount of graphene in the suspensions. The nonlinear optical properties of the mixture of ZnO nanoparticles and graphene nanosheets were also investigated using open and close z-scan experiments. The positive nonlinear refractive index and absorption coefficient of the mixture of graphene nanosheets and ZnO nanoparticles were increased with increasing the concentration of graphene in the mixtures.