客体材料对主客体掺杂体系二阶非线性光学特性的影响

Investigations on the Second-Order Nonlinear Optical Properties of Different Guest Materials in Host-Guest System

用溶胶-凝胶法分别将3种不同的偶氮材料与聚甲基丙烯酸甲酯(PMMA)掺杂,并制备成旋涂膜,测量了薄膜的厚度、折射率和紫外-可见吸收谱。用实时电晕极化装置测量了3种薄膜二次谐波产生(SHG)强度随时间的变化关系。实验结果表明,含有不同取代基的偶氮材料,取代基给(受)电子能力越强,导致微观一阶超极化率β越大,β越大决定了偶氮分子越容易被极化,最终导致宏观二阶非线性光学特性越大。3种偶氮分子的有效倍频系数分别为0.748,0.794,4.420 pm/V。

The films of polymethyl methacrylate （PMMA） doped three different azo compounds are prepared by using spin coating method. Their thicknesses, indices of refractive and UV-Vis spectra are measured. The second harmonic generation （SHG） densities are detected by real-time corona poling method. For the azobenzene molecules with different substituents, the stronger the ability of pushing （pulling） electron is, the bigger the value of SHG is. The effective frequency-doubling coefficients of the three systems are 0. 748, 0. 794, and 4. 420 pm/V respectively. The results show that because the ability of pushing （pulling） electron is different, the first-order hyperpolarizability is different, which determines whether the molecule is poled easily or not.