Modification Study Of PMMA Poled Polymer Optical Waveguide Thin Films

In this thesis, the literature researches on the organic polymer film waveguides and their applications to optical devices were firstly made. In specialty, the research advancement of the nonlinear optical characteristics of poled polymer film waveguides and their devices were given. Based on the preliminary investigation, the polymethyl methacrylate (PMMA), which is recognized as one of the most promising host materials of polymer waveguides, was selected to develop the poled polymer films. In addition, the nano-silicon dioxide (SiO₂) and disperse red1 (DR1) grains were used as the modifying agents.Both PMMA film samples modified respectively by nano-silicon dioxide and disperse red were prepared, adopting different matching compositions and technological process. And then these samples were characterized and analyzed by using various advanced methods.Four aspects, including the surface appearance, transmittance, thermal stability and refractive index of modified PMMA films, were mainly discussed here. The fabrication process of the inorganic nano-modified organic polymer system was synthetically summarized, and the effects of the contents and the sizes of SiO₂ nanometer particles and DR1 grains on the PMMA film performance were analyzed on the microscopic level.Moreover, the nonlinear optical performances of modified PMMA films were studied in detail. The basic scheme and the improved methods were proposed to pole modified PMMA films and measure their second-order NLO coefficients, according to the comparison and analysis of several representative poling and test methods.And then the experiment platform of corona poling and coefficient-testing system was built using advanced equipments with the help of the other association. With this platform, two PMMA film samples with and without nanometer SiO₂ particles modification were corona poled. Using the Maker-fringe methods, the second-order NLO coefficient d33 were measured. And the d33 values of the two samples were 5.02×10^-9 esu and 12.66×10^-9 esu respectively, indicating that the nano-particles modified film sample has better second-order NLO characteristic.Furthermore, the spectral analysis of the two kinds of samples also shown that the second-order NLO characteristic of the nano-modified film sample was better. Especially, the microscopic mechanism of the change of the second-order NLO characteristic in nano-modified film sample was discussed by analyzing the distribution of the SiO₂ nanometer particles in the polymer network. The results suggested that the nano-modified PMMA films have better relaxation characteristic.Based on K-M model and Mie theory, an UV scattering model for the study of PMMA nano-modified polymer had been also established. Making Mie scattering arithmetic functions and visual programs in MATLAB and analyzing the astringency condition, the quantitative relationships between nano particle sizes and transmittance have been theoretically calculated. The simulation results of the scattering model are in good agreement with the experiment results. Finally, utilizing the impact of polarization on particle scattering, we propose that polymer waveguides and devices can be performed by using UV light source with polarizer. The optimum particle size is determined in 70～80 nm on the basis of consideration of polarization mechanism of nature light and polarized light.The conclusions of the present study provide theoretical and experimental references for further investigations on the design of organic polymer waveguides and devices, especially for inorganic nano-modified poled polymer system.