Quadratic Non-Linear Optical Properties of the poly(2,5-bis(but-2-ynyloxy) Benzoate Containing the 2-(ethyl(4-((4-nitrophenyl)buta-1,3-diynyl)phenyl)amino)ethanol) Chromophore.

Excellent quadratic non-linear optical (ONL-2) properties of the poly(2,5-bis(but-2-ynyloxy) benzoate, containing a polar diacetylene as a chromophore, were found. According with the Maker fringes method, oriented polymer films showing an order parameter of ∼0.23 can display outstanding and stable Second Harmonic Generation (SHG) effects under off-resonant conditions (SHG-532 nm). Also, the macroscopic non-linear optical (NLO)-coefficients were evaluated under the rod-like molecular approximation, obtaining: χzzz(2) and χzxx(2) in the order of 280 ± 10 and 100 ± 10 pm V-1, respectively. The mechanical and chemical properties, in addition to the large ONL-2 coefficients exhibited by this polymer, make it a promising organic material in the development of optoelectronic/photonic devices.

Synthesis of porphyrin-dendrimers with a pyrene in the periphery and their cubic nonlinear optical properties.

Dendrons of pyrene derivatives were attached to a porphyrin core. A marked effect in solution for the dendrimers was observed in the absorption spectra. All the compounds obtained were characterized by (1)H-, (13)C-NMR, FTIR, UV-vis, MALDI-TOF or FAB+ mass spectrometry and elemental analysis. The cubic nonlinear optical behavior of some the synthesized compounds was tested via Z-Scan measurements in spin-coated film samples.

Optical absorption photoacoustic measurements for determination of molecular symmetries in a dichroic organic-film.

A novel approach to specify symmetries and main optical axes in anisotropic polymeric films is proposed. This method is based on the analysis of the optical absorption via the pulsed laser photoacoustic (PLPA)- technique in a common polarizer film, while rotating the polarizer axis at normal incidence. Since the PLPA-signals are directly proportional to the optical absorption, it is shown that a symmetric and complementary Malus's law can be obtained over full root mean square (RMS)- and correlation (CA)-analysis of the PLPA-signals. Such data processing reveals the main material directions of the constituting film molecules defining the symmetry structure of the sample. PLPA-results were compared to the pure optical transmission experiments and show unambiguous information, allowing this technique to be used in nonstandard and opaque polymeric films, where the analysis of the optical measurements represents a difficult task, and in general, in anisotropic media.

Preparation of fullerene (C60) based SiO2 sonogel hybrid composites: UV laser induced photo-polymerization, morphological, and optical properties.

Fullerene (C60) spheres were successfully embedded by diffusion into a catalyst-free SiO2 sonogel network. By this method, homogeneous and stable solid state hybrid samples suitable for optical characterization were produced. Due to the high porosity exhibited by the sonogel matrix on the nanometric length-scale, the preparation of several C60 doped composites with variable dopant concentrations was achieved. The obtained bulk hybrids were irradiated with a pulsed Kr-F laser system in order to induce photo-polymerization of the implanted C60 guest molecules at optimal experimental conditions established according to the pulsed laser photoacoustic technique (LPAT). The adequate purity level displayed by the sonogel route allowed us to perform optimal optical characterizations of these composites (reference hybrids and photo-polymerized samples) in order to evaluate their photo-physical properties for potential photonic applications. In this work the sonolysis process used to prepare amorphous catalyst-free SiO2:C60 sonogel hybrids and their linear and nonlinear optical (NLO) properties are extensively discussed. UV-VIS absorption-, Photo Luminescent (PL)-, and Raman-spectroscopies in conjunction with nonlinear optical limiting (OL) measurements, gave experimental evidence of the inclusion of C60 molecules within the sonogel environment, the laser induced photo-polymerization process and the induced changes of the optical and NLO-properties. Results are discussed in combination with atomic force microscopy (AFM) studies in order to explore the surface morphology of these samples.