Nonlinear optical properties of heavy metal and transition metal oxides

本论文以设计新型无机非线性光学材料为目标，采用三次谐波产生（THG）方法和Z扫描方法研究了熔融法制备的含过渡金属氧化物玻璃和溶胶-凝胶法制备的含d电子和不含d电子的过渡金属氧化物薄膜的非线性光学性质。由于CCD探测器可以同时检测四路信号，并且具有高信噪比，因此可以在很短的时间内测量可靠的数据。通过对溶胶-凝胶法制备的过渡金属氧化物薄膜的三次谐波测量，发现Fe^3+和Pb^2+离子具有较高的二阶超极化率。使用不同的氧化铁，铁的氧化态和配位态，和晶体结构的二阶超极化率（γ）的影响进行了研究。氧化态（Fe^<2+> * Fe^<3+> * Fe^<4+>）越高，配位数（4 * 6）越大，二阶超极化率（γ）越大。在相位匹配条件下，用1.9 μ m激光入射，观察到TiO_2（110）单晶的明显红光三倍频信号。研究了d电子对含过渡金属氧化物TeO 2玻璃非线性光学性质的影响。根据Lines最初提出的修正的键轨道理论解释了这些结果。

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.