The nonlinear optical absorption and switching properties of sol-gel derived of Au nanoparticle doped SiO 2-TiO 2 sol-gel films having different Au-surface plasmon absorption positions are reported in this paper. The Au nanoparticles are embedded in SiO 2 and SiO2-TiO 2mixed glassy film matrices with different refractive index values. To study the nonlinear absorption properties, lasers with three different wavelengths are used. The optical switching behavior is studied by using the pump-probe technique with 532 nm as the excitation wavelength. Ground state conduction band, surface plasmon band, and the free carrier band are taken as three level model to explain theoretically the obtained RSA and SA behaviors. Copyright © 2006 American Scientific Publishers All rights reserved.