分子结构对偶氮化合物薄膜全光极化特性的影响  

Effect of Molecular Structure on Character of All-Optical Poling about the Azo Compound Thin Films

作　　者：李云[1] 王文军[1] 刘云龙[1] 高学喜[1] 李慧[1] 

机构地区：[1]聊城大学物理科学与信息工程学院,山东聊城252059

出　　处：《中国激光》2009年第8期2140-2143,共4页Chinese Journal of Lasers

基　　金：国家自然科学基金(10874063);山东省自然科学基金(Y2007A34);山东省教育厅科技发展计划(J07YI05)资助课题

摘　　要：利用旋涂法制备出4种主客体掺杂型有机薄膜,并对其进行厚度、折射率、紫外-可见吸收谱以及全光极化后二次谐波的测量。实验结果发现,对于厚度相同的薄膜,全光极化后的二次谐波产生(SHG)值与偶氮苯分子的偶极性强弱有关,偶极性越强SHG值越大。计算结果表明,在这4种薄膜中,二阶非线性光学系数d_(33)最大为4.97×10^(-1)pm/V,其偶氮分子结构特征是连接在苯环上的硝基(-NO_2)的吸电子能力最强,而d_(33)最小为2.55×10^(-2)pm/V,与最大的相差一个数量级。这些结果在理论上可以解释为:主要是由于不同分子结构的材料其偶极性强弱不同而使它们受光激发的难易程度不同,最终导致宏观表现出来的SHG值不同。这将为分子材料的设计提供实验依据。Four kinds of guest-host adulterate thin films were prepared by using spin-coating method, and then their thickness, refractive index, UV-Vis spectra and the signal of second harmonic generation （SHG） after all-optical poling were measured. The experimental result was shows that the value of SHG depends on the dipole property of azobenzene molecule for the same thickness, and the stronger the dipole property of azobenzene molecule is, the bigger the value of SHG is. Calculation result shows that the nitryl （-NO2） connected with benzene has the biggest second-order nonlinear optical coefficient d33 that equals to 4.97 × 10^-1 pm/V, and the weakest equals to 2.55 × 10^-2 pm/V. It can be explained in theory that different dipoling induces the different excitation extent for these azobenzene molecules. This work can offer a powerful experimental help to the design of molecular materials.

关 键 词：薄膜 二次谐波产生 全光极化 偶氮化合物 

分 类 号：O484.4[理学—固体物理]