Nonlinear optical absorption of InAs nanocrystals embedded in SiO2, films p
repared by radio-frequency magnetron cosputtering was studied by Z-scan tec
hnique using a single Gaussian beam of a He-Ne laser (633 nm). Both two-pho
ton absorption and saturation absorption were observed. The enhanced third-
order nonlinear optical absorption coefficients were obtained in the compos
ite film. Our results indicate that the type and magnitude of the nonlinear
optical absorption coefficient of the composite films are related to the a
verage size of the nanocrystals. (C) 1999 Elsevier Science Ltd. All rights
reserved.