Nonlinear optical properties of PbO–GeO2 films containing gold nanoparticles

The third-order susceptibility of glassy PbO–GeO2 films containing gold nanoparticles (NPs) was investigated in the pico- and sub-picosecond regimes. The nonlinear refractive indices, n2=(6±1)×10−10 cm2/W measured at 532 nm and n2=(10±2)×10−13 cm2/W at 800 nm, are larger than the values obtained for films without gold NPs by more than one order of magnitude. On the other hand, because the films were heat-treated in an oxygen atmosphere, the value of the two-photon absorption coefficient at 800 nm was reduced by two orders of magnitude in comparison with previous report. The new results demonstrate the large influence of the gold NPs and the fabrication procedure on the optical response of the samples.