Nonlinear optical properties of heavy metal and transition metal oxides

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In this research, we have investigated the nonlinear optical properties of melt-derived oxide glasses containing transition metals and sol-gel derived transition metal oxide films with and without d-electrons by means of the third harmonic generation (THG) method and Z-scan method aiming at designing novel inorganic nonlinear optical materials.First, we assembled the Z-scan optics by using the CCD detector which were purchased. Since it can detect four channel signals at the same time and at the high S/N ratio, the CCD detector made it possible to measure the reliable data in a very short time. From the THG measurements on the sol-gel derived transition metal oxide films with or without heavy metal oxides, Fe^<3+> and Pb^<2+> ions were found to have high second-order hyperpolarizabilities. Using various iron oxide, effects of oxidation states and coordination states of iron, and crystal structure on the second-order hyperpolarizability (gamma) were investigated. The higher the oxidation state (Fe^<2+> * Fe^<3+> * Fe^<4+>) and the lager the coordination number (4 * 6), the larger the second-order hyperpolarizability (gamma). Using l.9m laser light as a incident beam, a conspicuous red THG signal were observed for TiO_2 (ll0) single crystal under the phase matching condition. The effects of d- electron on the nonlinear optical properties of transition metal oxide-containing TeO2 glasses were investigated. The results were explained based on the modified bond orbital theory originally proposed by Lines.