Optical second harmonic generation and relaxation dynamics of aligned azo-dyes in sol-gel derived organic-inorganic film

An Azo-dye doped organic-inorganic hybrid film was prepared by the sol-gel technique, and optical second-harmonic (SH) nonlinearities were measured as a function of the poling conditions. Azo-dye molecules dispersed in poly-vinylpyrrolidone were complexed with the hydrolyzed silicon-alkoxide. The Maker-fringe pattern composed of a fine oscillating pattern on a broad component, and the highest second-order nonlinear coefficient, d(33), was 0.83 pm/V when poled at 175 degreesC and 4 kV. The analysis of the decay curves of the SH intensities at 150-190 degreesC predicted the relaxation time of about 3 years at room temperature.