| The better optical instrument is needed for the information technology and mechanics of communication developing rapidly under the force of photoelectron science. Went along with it, the nonlinear optical materials interrelated with optical instrument is developed quickly. The macromolecule polymer PPV and PPV derivatives have received much attention for the application on polymer light-emitting diode(PLED). It exhibits good characteristics not only in irradiation aspect but also in the nonlinear optical aspect for the structure of π bond in the molecule. So the PPV materials become one of important study directions in nonlinear optical material fields. At the same time, the value of nonlinear refraction and kerr constant both are important parameters which can reveal intensity of the third-order optial nonlinearity. So the measurement of optical nonlinear optical coefficient is very important.In this paper, the microcosmic mechanism of macromolecule polymer's third-order nonlinearoptical character is analyzed and the factors affecting material's nonlinear character are described. By dehydrochlorination reaction the poly[(2-methoxyl-5-octyloxy)phenylene vinylene](MO-PPV) is synthesized and the material's structure is characterized by nuclear magnetic resonance spectroscopy, infrared absorption spectrum, ultraviolet and visible spectrophotometry. At the meantime, the fluorescence spectrum is measured and the mechanism of fluorescence occurring is analyzed. Thermal Gravimetric Analyzer's results show that the MO-PPV's thermal stability is fine. Also the experiment of resolvable property indicates that the MO-PPV can well dissolve in chloroform. Through analyzing the film's surface by Metaloscope and Atomic Force Microscope, the good filming is found. The studies of material conductivity indicate that solid material performance conductivity only when the material is intermingle, and the conductivity of solution material is different for the different solvent and the conductivity is changing along with the length of time. Furthermore, the linear refraction index and linear absorption coefficient of MO-PPV film and solution is measured. Based on the ultraviolet and visible spectrum, the width of optical forbidden band of MO-PPVfilm is calculated and the value is 2.09eV.The formula to calculate the third-order nonlinear coefficient is deduced in theory in the studying of nonlinear optical character. Then the Z-scan experimental optical system is set up. In experiment, the data are collected automatically through writing programs by Labveiw software, which makes the experiment conveniently. The film and solution of MO-PPV is measured in the Z-scan experiment when the laser wavelength is 532nm. Observing the Z-scan curve we know the solution shows self focusing out effect while the film shows self focusing effect. By analyzing and calculating, the MO-PPV solution's nonlinear refraction index n2 =-1.78x10-11 esu, the absorption coefficient β = 2.99×10-12 cm/W, the... |
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