Studies of third-order nonlinear optical phenomena on Yb3+/Tm3+. co-doped PbO-GeO2 glasses containing different concentration of silicon nanoparticles are presented. The well-known melting-quenching technique was used for the production of the samples. Measurements were performed using conventional Z-scan, SHG and ESHG methods with Q-switched mode-locked ns scale Nd-YAG lasers, intensities in the 0.8-1.2 GW/cm(2) power density range and repetition rate of 10 Hz. Maximum third-order susceptibilities and second harmonic generation were found for the sample prepared with 1 wt% of Si powder. (C) 2016 Elsevier Ltd. All rights reserved.