Nonlinear Optical Properties And Optical Limiting Of Fullerene Derivatives

With the wide application of photo-electronic devices,the nonlinear optical material are received advanced research. Fullerenes reveal large nonlinear optical properties due to the special structure. So the fullerene and its derivatives are investigated deeply. All the research demonstrates that the fullerene derivatives possess not only the large third order nonlinear optical properties, but also the large second order nonlinear properties because that the substitute group break the symmetrical structure of C60. Moreover, the third-order nonlinear electric susceptibility of C60 derivates is increased with the accretion of effectiveπconjugation length. It offers a new direction to designing and synthesizing the novel material with large nonlinear optical properties. Currently, as a large nonlinear optical materials, C60 and its derivates have been attracted much attention.In the thesis, nonlinear optical properties of six novel fullerene derivates were investigated by Z-scan technique. And the result of the investigation reveals that substitute groups affect strongly on the nonlinear optical properties.The thesis includes four chapters.Chapter one, the current status of the development and practical applications of nonlinear optics are introduced briefly,the third-order nonlinear optical effect is introduced particularly. In addition, the theory and the method of Z-scan technique are described for the measurement of nonlinear optical coefficients.Chapter two, the nonlinear optical properties of the six novel C60 derivates are investigated under continue wave 488nm, 633nm laser excitation by Z-scan technique. The value of thermal-optical coefficients and nonlinear refraction index is calculated from the data of the experiment. The result demonstrate that thermal-optical coefficients of the six novel compounds correlate with wavelength of the laser, the absorption coefficients at corresponding wavelength, and the structure of these compounds. At last, the optical limiting of the C60 derivates is investigated.Chapter three, this work is devoted to investigation nonlinear optical response in fullerene derivates under picosecond laser excitation. The wavelength of laser is 1064nm and 532nm. The third order nonlinear refraction index, molecular second order hyperpolarizability and nonlinear absorption coefficients are attained by fitting the experimental dates. The relationship of the nonlinear optical properties and the molecular structure is analyzed. And the good optical limiting properties are also revealed.Chapter four, discussions and conclusions are made.