Nonlinear optical response of Au and Ag nanoparticles doped polyvinylpyrrolidone thin films

Colloidal Au and colloidal Ag were prepared by chemical reaction method and the nonlinear optical properties of Au and Ag nanoparticles doped polyvinylpyrrolidone (PVP) composite films were investigated using Z-scan technique with 38 ps pulses at 532 nm. Open aperture Z-scan measurements indicated that both the Au/PVP and Ag/PVP composite films exhibited reverse saturable absorption. Nonlinear absorption coefficients and third-order nonlinear refractive indices were determined. The mechanisms accounting for the process of nonlinear refractions were analyzed and the figures of merit W and T of the Au/PVP and Ag/PVP composite films were evaluated.