3RD-ORDER NONLINEAR-OPTICAL PROPERTIES IN LANGMUIR-BLODGETT-FILMS OF 4-DOCOSYLAMINO-4-NITROAZOBENZENE

The third-order nonlinear optical properties of 4-docosylamino-4-nitroazobenzene (DANAB) Langmuir-Blodgett (LB) films were investigated. The orientation of the DANAB molecules in the LB film is designed to be aligned virtually perpendicular to the substrate by mixing DANA-B and fatty acid, which has the effect of preventing the cascading effect. It was found that DANAB film, mixed with a fatty acid, form H aggregates. The frequency dispersion was measured using the third harmonic generation method with the optical parametric oscillator. It is indicated that the third-order nonlinear optical susceptibility [chi(3)] is enhanced because of the resonance and molecular aggregation effects. The value of the chi(3) under the resonant condition of 3. 1 X 10(-12) esu and that under the nonresonant condition of 1.5 x 10(-12) esu were obtained.