Preparation And Properties Of New Nonlinear Optical Film Study

Nonlinear optics, as a new subject, has showed great application foreground in the fields of modern laser technology, optical communication, data storage, optical information processing, etc. in the past decades. The organic polymer has developed rapidly and attracted considerable attentions by scientific research institutions, companies and military, due to its superior NLO characteristics compared with inorganic materials.Several mainly used NLO materials were reviewed in this thesis, second-order organic polymer NLO materials and their latest progress were recited. In our research, we study two kind of organic nonlinear optical material. One is organic poling polymer material, the other one is organic LBL assembly material.The new organic nonlinear optical(NLO) chromophore molecules DCDHF-2-V and GW-1-SF were doped in poly (methyl methacrylate) (PMMA) respectively with a certain concentration by weight. The DCDHF-2-V/PMMA polymer thin film was fabricated by spin-casting method. For a macroscopic second-order NLO effect, the film was corona poled to induce a noncentrosymmetric organization of chromophore dipoles. For GW-1-SF/PMMA polymer thin film, we use a new method to deposite the polymer thin film. For the sake of fitting, we choose touching poling for this depositing method. Details of purification of the polymer, cleanouting of the substrate, preparing of the solution and the process of spin-casting techniques were described in this thesis.The different two polymer thin films have been investigated by the UV/Visible absorption spectra before and after poling. The Atomic Force Microscopy (AFM) images of the polymer films showed that the surface of the film sample is extremely flat and clean. The refractive index and the thickness of the film were measured by ellipsometer. The second-order nonlinear coefficient d₃₃ value of the two different kind of thin films reached 15.2pm/v and 17.8pm/v at 1064 nm wavelength. The relation between the second-order nonlinear coefficients d₃₃ and d₁₃ for the poled polymer film was also discussed in detail. In the study of LBL assembly material, a promising methodology for fabricating high thermally stable organic second-order NLO thin films containing low molecular weight chromophoric (LMWC)molecules PAZO was sustained by layer-by-layer assembly. Based on the static power, the density of the oriented deposited chromophores PAZO deposited on the substrate is increased largely and upon the UV irradiation, accompanied with the transition of the ionic bonds between the layers to covalent bonds, the resulting NLO films possess excellent environmental stability and high thermal stability, which may rival the properties of the latest poled polymer films for electro-optic devices.