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Search for Organic Nonlinear Optical Materisls and Estimation of Figure of Merit

有机非线性光学材料的搜索和品质因数的估计

基本信息

批准号：
61550006
负责人：
UMEGAKI Shinsuke
金额：
$ 1.28万
依托单位：
Tokyo Engineering University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

1. As compact and modified method of electric-field induced second-harmonic generation has been developed for measuring the secon-order hyperpolarizability of organic moleucules. The method can also remove the inevitable effect of interference to the prevoius method between the second-harmonic waves henerated at the cell windows and the second-harmonic wave to be mesaured. Theoretical expressions have newly been derived to desctibe the mactoscopic nonlinear polatixzations associated with this new configuration. It has been applied to organic molecules, p-NA and MNA, whose hyperploarizabilities were already known and applied to unkown MBA-NP, PNP and DAN. The results of measurement coincide well with the thoretical calcultaions using a P-P-P and a CNDO/S method.2. It has been concluded that the powder method for evaluating a figure of merit of second-order nonlinearity of crystals should not be utilized for the organic crystals, since the coherence lengths of such crystals with well-aligned molecules are too short. Only ceystals with molecules nearly parallel to each other could surpass d33 of LN, which was used for and efficient frequency doubler of a semiconductor laser in the form of a waveguide devices. The new of or improved method instead of the powder method is needed in order to seek easily useful organic materials.3. For flaky crystals, whose hyperpolarizabilities large enough, two procedures have been proposed to estimate htier figure of merit. One, for crystals with an optical grade, is to measure the refractive indices by means of a spectrometer or an ellipsometry, and the other, for crystals with an optically deteriorated grade, is to analyze and to know the orientation of molecules in the crystal by an X-ray method. Both procedures have been found to be comlimentary, from the results of measurement of MBA-NP and DAN.

1.作为一种紧凑的改进方法，电场诱导二次谐波法被发展用于测量有机分子的二阶超极化率。该方法还可以消除在单元窗口产生的二次谐波与待测二次谐波之间对普雷沃伊斯法不可避免的干扰影响。新的理论表达式已经推导出描述与这种新的配置相关的宏观非线性极化。它已被应用于有机分子，p-NA和MNA，其超极化率是已知的，并应用于未知的MBA-NP，PNP和DAN。测量结果与P-P-P法和CNDO/S法的理论计算结果吻合较好.它已得出结论，粉末法评估的二阶非线性晶体的品质因数不应用于有机晶体，因为这种晶体的相干长度与良好的排列分子太短。只有分子几乎相互平行的晶体才能超过LN的d33，LN被用于波导器件形式的半导体激光器的高效倍频。为了寻找更容易得到的有用有机材料，需要用新的或改进的方法代替粉末法.对于超极化率足够大的单晶，本文提出了两种方法来估算其优值。一种是对于具有光学等级的晶体，通过光谱仪或椭圆偏振法测量折射率，另一种是对于具有光学劣化等级的晶体，通过X射线方法分析并知道晶体中分子的取向。从MBA-NP和DAN的测量结果来看，这两种方法都是互补的。