Development of Nonlinear Optical Waveguiding Devices for Second-Harmonic Generation of Laser Diode Light

1. 对多种有机晶体进行了基于量子化学分子轨道计算的分子超极化率理论计算和基于定向气体模型的二阶光学非线性系数理论估计。提出了一种包括理论计算在内的新的筛选表征方法。以激光二极管为光源的表征方法也得到了新的发展。对平板波导和光纤波导的切伦科夫辐射型二次谐波产生进行了理论研究。这些理论分析为优化波导参数和选择适合有效倍频的材料提供了可能。提出了一种利用有机材料溶液制作波导的新技术。一种制作精细图案的技术(1)。利用有机晶体制备s - 3mum；水溶性无机光刻胶材料HPA和O_2-RIE使制备可溶于有机溶剂的有机晶体成为可能。这项新技术有望适用于几乎所有的有机材料。利用有机波导和激光二极管光源，以切伦科夫辐射的形式产生二次谐波蓝光。研究了二次谐波光的聚焦特性。我们相信这些结果对有机非线性光学材料倍频器件的发展有很大的贡献。

1. Theoretical calculation of the molecular hyperpolarizabilities based on the quantum-chemical molecular orbital calculations and theoretical estimation of the second-order optical nonlinear coefficients based on the oriented-gas model were performed for a variety of organic crystals. A new screening-characterization procedure which includes the theoretical calculations was proposed. A characterization method using laser diodes as light sources was also newly developed.2. The Cerenkov-radiation-type second-harmonic generation from slab and fiber wave-guides was theoretically investigated. These theoretical analyses make it possible to optimize wave-guide parameters and to select the materials which is suitable for effective frequency doubling.3. A wave guide fabrication technique using solutions of organic materials was newly developed. A technique for fabrication of fine patterns (1. s. - 3mum) using organic crystals was also developed ; the water-soluble inorganic photoresist material HPA and O_2-RIE made it possible to fabricate organic crystals which were soluble in organic solvents. This new technique is expected to be applicable to almost all of organic materials.4. Blue light was obtained by second-harmonic generation in the form of Cerenkov radiation using organic wave-guides and laser diode sources. Focusing characteristics of the generated second-harmonic light was also investigated.We believe that these results greatly contribute to the development of the frequency doubling devices using organic nonlinear optical materials.