OPTICAL NON-LINEAR MEASUREMENTS IN CDS DOPED SILICA FILMS

Samples of CdS doped silica thin films have been prepared with weight concentrations ranging from 0.5 to 20% (CdO/SiO2). Nanocrystal structu re and size distribution are determined by Transmission Electron Micro scopy (TEM) and image analysis. The mean size is tile same for all con centrations (4 nm) and is related to the matrix porosity. The linear a bsorption shows characteristic features of the excitonic level and the gap blue shift due to the quantum confinement. Non-linear optical pro perties are studied by Degenerate Four Waves Mixing (DFWM) to measure the third order susceptibility chi((3)) which is high (typically 10(-7 ) esu) and depends linearly of the volume fraction of the semiconducto r particles.