Research Of Cu_xO/SiO₂Composite Thin Film Preparation And Optical Nonlinearity

The nonlinear optical material thin films have promising applications in opticalcommunication, laser technique and nano optical molecular technology and other fields.CuxO based nonlinear optical thin film has been attracted much attention because of itslow cost. So it is very important to research and develop the materials of CuxO withexcellent third-order nonlinear optical properties. In this dissertation, CuxO/SiO2composite films were prepared by using the electrochemical sol-gel method combinedwith heat treatment. The third-order nonlinear optical properties of the as-preparedCuxO/SiO2composite films and the nucleation mechanism of copper in the sol werestudied.The stable and transparent CuSO4-SiO2composite sols with different pH valueswere prepared by using copper sulfate and tetraethoxysilane as precursors. The Cu/SiO2composite films were obtained by electrochemical sol-gel method using the preparedcomposite sol as electrolytes. The films characterized as CuO/SiO2and Cu2O/SiO2composite films by XRD and SEM/EDX were obtained by heating the as-preparedCu/SiO2composite films at250℃and450℃, respectively. The third-order nonlinearoptical susceptibility χ(3)of these composite films were calculated by fitted valuesresults from Z-scan combined with their linear optical parameters and thickness. The χ(3)of these composite films were107to106esu, which demonstrated that the third-ordernonlinear optical properties of the films were excellent.The CuO/SiO2and Cu2O/SiO2composite films were also obtained in CuSO4-SiO2composite sols with the different EG, PEG, JGB and MPS+Cl-additives. The third-ordernonlinear optical susceptibility χ(3)of these films reached107esu.Electrodeposition and electrocrystallization of copper from CuSO4silica sol withdifferent pH were investigated by cyclic voltammetry (CV) and chronoamperometry(CA) elctrochemical techniques. The results indicated that copper electrodeposition inthe CuSO4silica sol with different pH electrolytes could be well accorded withinstantaneous nucleation and three-dimensional growth mechanisms. The transfercoefficient of Cu2+in adsorption process lager than0.9, which demonstrated thepresence of adsorbed layer on the electrode. The total charge for the adsorption processQadswas increased as pH increases of the electrolytes.