Structural characterization and linear and nonlinear optical properties of polymer materials.

摘要

Well ordered, smooth, and surfactive polymer films with precise control over the thickness at the molecular level can be synthesized using the Langmuir-Blodgett (LB) technique. This technique was employed to prepare monolayers of two classes of polymers such as polypyrrole and polydiacetylene. The microstructures of these monolayers were investigated using transmission electron microscopy and scanning electron microscopy, optical microscopy, and Raman scattering. Electron diffraction from LB films of polypyrrole revealed that polypyrrole formed at the air-water interface is dictated into a new crystalline organization which is substantially different from the bulk grown film. A monoclinic lattice was proposed whose d-spacings were found to be in excellent agreement with the experimental values. The configuration of the proposed monoclinic lattice was also close to that obtained by other researchers for a possible crystalline lattice of polypyrrole.; It is extremely important to measure waveguiding properties such as propagation constants, number of modes, propagation losses, thicknesses, and refractive indices of the materials, in order to evaluate their performance as electro-optic waveguide modulators or other waveguide devices such as frequency doubler. Thin film slab waveguides of a number of nonlinear optical (NLO) polymers such as guest-host system, side chain polymer, and photocrosslinkable polymer were fabricated on glass, silicon oxide on silicon, and fused quartz by spin-coating the polymer solution. The prism coupling technique was used to investigate waveguiding properties of these NLO polymers. These polymers were found to form good optical quality films with low propagation losses (1-5 dB/cm) and can be used for fabrication of waveguide devices.; Poled electro-optic polymers have exhibited the promise of large electro-optic coefficient, high bandwidth, low power dissipation and ease of integrated fabrication with existing electronics. The electro-optic coefficients of a poled and photocrosslinked polymer containing a new azo dye were measured using the reflection method. Although, the electro-optic coefficients for this system for low concentration of dye are not large, they can be increased significantly by increasing the concentration of dye in polymer or using alternate NLO molecular subunits.