Synthesis of Polymers and Oligomers for Nonlinear Optical Activity

通过优化电子离域和分子内电荷转移，制备了三阶非线性极化率大于10-9esu的聚合物薄膜。对于原始材料，优值系数高达104。掺杂(分子间电荷转移)在某些情况下会产生更大的值。在初步研究中制备的梯形和苯基多烯材料也表现出掺杂诱导的视觉透明，即pi-pi*带间跃迁的漂白和伴随的带内(极化子/双极化子)跃迁的出现。观察到给电子和引出取代基稳定了这些中间能隙状态的物种。研究了离域pi电子系统与分子氧的反应性，证明了电子离域中断对非线性光学活性的影响。这项研究的重点是进一步开发聚合物、共聚物和增强非线性光学活性的复合材料。特别注意空气稳定材料的开发以及模型化合物(低聚物)和聚合物数据的关联。将开发线性和非线性光学材料的共聚物和复合材料。组件的选择将使折射率在低光强下匹配，但在高光强下不匹配。

By optimizing electron delocalization and intramolecular charge transfer, polymers yielding third order nonlinear optical susceptibilities in excess of 10-9 esu have been prepared as thin (1 micron) films. Figures of merit as high as 104 have been obtained for pristine materials. Doping (intermolecular charge transfer) yields even larger values in some cases. Ladder and penylpolyene materials prepared in preliminary studies also exhibit doping-induced visual transparency, i.e., bleaching of the pi-pi* interband transition and accompanying appearance of intraband (polaron/bipolaron) transitions. Electron-donating and withdrawing substituents are observed to stabilize these mid-gap state species. The reactivity of delocalized pi electron systems with molecular oxygen has been investigated and the effect of interruption of electron delocalization upon nonlinear optical activity has been demonstrated. This research focues upon further development of polymers, copolyers, and composite materials for enhanced nonlinear optical activity. Particular attention is paid to the development of air-stable materials and to correlation of data obtained for model compounds (oligomers) and polymers. Copolymers and composites of linear and nonlinear optical materials will be developed. Components will be so chosen that indices of refraction are matched at low light intensities but are mismatched at high intensities.