Preparation And Nonlinear Optical Properties Of Reduced Graphene Oxide-TiO₂ Nanocomposites

In today’s high-tech war,laser weapons are undoubtedly the most effective directional energy weapons to destroy or make satellites ineffective,and laser weapons have broad research prospects and creativity.In contrast,the emergence of laser protective materials,in which the absorption coefficient of laser protective materials based on the principle of nonlinear optics changes with the change of light intensity.It can absorb both strong and weak lasers at the same time,which makes up for the limitations of laser protective materials based on the principle of linear optics to a great extent.Therefore,the research on nonlinear optical materials has become a new research hotspot.Titanium dioxide（TiO₂）has high transmittance from the visible region to the infrared region,good thermal and chemical stability,and excellent optoelectronic properties;reduced graphene oxide（r GO）has a special energy band structure and high carrier mobility,and has attracted great interest in the fields of nanocomposites and optoelectronic devices.In this study,r GO with excellent optical limiting properties and TiO₂with high visible light transmittance were selected to prepare composites and investigate their nonlinear optical properties and optical limiting properties.The reduced graphene oxide-titanium dioxide（rGO-TiO₂）nanocomposites were prepared by solvothermal method,and the morphology of the products were characterized by transmission electron microscopy（TEM）and scanning electron microscopy（SEM）;the structures of the products were characterized by X-ray diffraction（XRD）,ultraviolet absorption spectroscopy（UV-Vis）,and Raman spectroscopy;finally,a Z-scan tester（Z-Scan）was used.Finally,the nonlinear properties of the r GO-TiO₂nanocomposites were tested using a Z-scan tester（Z-Scan）（1030 nm,340 fs）at the incident light intensities of 10.4 GW/cm²and 20.8 GW/cm²,indicating that the Z-scan images of the r GO-TiO₂nanocomposites were symmetrical valleys exhibiting anti-saturation absorption properties.The theoretical nonlinear coefficients were calculated to be 572.01×10^-3cm/GW and 136.17×10^-3cm/GW,which are 5-20 times higher than those of pure GO,respectively.In addition,the normalized transmittance of r GO-TiO₂nanocomposites reaches a minimum of 30%,indicating that the material has good nonlinear and optical limiting（OL）properties,suggesting that this work expands the selection range of optical limiting materials.