▎ 摘　　要

In this work, Silicon oxide (SiO2) nanoparticles, graphene oxide nanosheet (GO) and GO-SiO2 nanohybrid composites have been synthesized. The role of GO concentration in the starting solution was investigated and correlated to the morphological, structural and optical properties of the studied samples. The structural studies for nanohybrid composites showed that by increasing GO:weight ratio from 0.5 to 2.0, not only does the SiO2 crystalline phase change from cubic to orthorhombic, but the structure of GO also transformed to RGO. The related FESEM images indicate that GO sheets are well-covered by SiO2 nanoparticles with very small grain size and that the accumulation of nanoparticles on each sheet has a high density. Linear Optical measurements showed two optical band gaps of similar to 3.2 eV and 5.3 eV for SiO2 nanoparticles, and band gap value of 4.15 eV for GO nanosheets, which it reduces to 3.3 eV after formation of the nanohybrid composite with GO: SiO2 weight ratio of 2.0. The nonlinear optical properties of GO-SiO2 with different weight ratio are measured using Z-scan technique. The results showed that the nonlinear refractive index of SiO2 and GO nanoparticles and nanohybrid composite (0.5:1,1:1,2:1) (GO-SiO2) changed and has a negative sign. It was observed that the nonlinear refractive index changes in different ratios of compounds. Experimental results show that after the formation of the composite, the nonlinear refractive index shows a significant increase in the presence and effectiveness of the GO.