NONLINEAR-OPTICAL PROPERTIES OF GAAS PARTICLES EMBEDDED IN SIO2 THIN-FILMS

Nonlinear optical absorption and nonlinear refraction were studied in ultrafine GaAs particles embedded in SiO2 thin films by use of the sin gle-beam Z-scan technique at room temperature. An enhanced third-order nonlinear absorption coefficient and nonlinear refractive index were measured to be about 10(-1) cm/W and 10(-3) esu, respectively. The sat urated optical absorption and two-photon absorption, under a 10(4) W/c m(2) irradiation intensity, were observed and discussed. Results show that the enhanced nonlinear effect mainly depends on the quantum confi nement effect. Under the strong quantum confinement condition, the Cou lomb interaction effect is negligible with respect to the quantum conf inement effect, and the feature of nonlinear optical effect of the GaA s particles behaves as a two-level system.