Preparation And Performance Of Second Order Nonlinear Optical Polymer Material With An Octupolar Compound As The Chromophore

With the development of optical communication and optical computing, second order nonlinear optical materials has become a research hotspot in the field of high technology. Second order nonlinear polymeric material (also called second-order NLOP material or polarized polymer) has not only good nonlinear optical properties (high nonlinear optical coefficient, super fast response speed), but also low dielectric constant, high threshold, low light absorption optical losses etc. Along with the advantages of possibility for designing and cutting, easy synthesis and structure stability, second order nonlinear optical polymers have more practical value and broad application prospects in the fields of frequency conversion and signal processing. However, a second order nonlinear optics request materials possessing a center asymmetrical structure. Because of the static electrical interactions among chromophore molecules, polymers with dipolar molecules as chromophores were difficult to satisfy the request completely. Octupoles possess nonpolar and center asymmetrical structures, which could be an important role as chromophores in organic nonlinear optical materials.In this thesis, an octupolar molecule was designed and synthesized with strong electron-withdrawing groups of three cyano mesitylene as core, which has triple axis of symmetry. Taking PMMA as matrix, with different doping concentrations of octupole, using spin coating technology, a series of polymer thin film were prepared. Thermal stability, as well as optical properties, and the second order nonlinear optical property of polymer thin film were studied. The main content of chapters in this thesis are as follows:The first chapter is the introduction. The research progress of second order nonlinear optical materials was briefly introduced, based on which, the work in this thesis was put forward.The second chapter is a review. Related works were briefly reviewed, including the basic principle, common optical nonlinear optical material and the category of the second order nonlinear optical materials, second-order nonlinear optical chromophores molecular design theory. The relationship between structure and performance of optical materials was discussed. The progress in second order nonlinear optical materials was introduced. The third chapter is about the preparation and characterization of an organic chromophore. An octupolar molecule (2,4,6-tris[4-dihexylaminostyiyl]-1,3,5-tricyanobenzene, HxTCB) was designed and synthesized, which was characterized with 1H-NMR,13C-NMR, FT-IR, Mass Spectrometry, and Elemental Analysis.The fourth chapter is about the preparation and properties of HxTCB doped PMMA film. PMMA films with different doping content of HxTCB were prepared using spin-coating technique. Thermogravimetric analysis (TGA) was used to study the thermal stability of the film. The optical properties were investigated by UV-Visible spectrum and fluorescence spectrum. The second order nonlinear optical property was studied by measuring the Electro-optic coefficient r33.