Ag/PVP nanocomposite thin film with giant optical nonlinearity

Ag/PVP nanocomposites were prepared by a chemical reduction process. Then, a drop-casting method was employed to deposit the Ag/PVP nanocomposite thin film on the glass substrate. To study the optical and structural properties of the prepared sample, different characterization methods including UV-Vis absorption spectroscopy, scanning electron microscopy, XPS, and Raman spectroscopy were employed. The optical nonlinearity of the prepared thin films was evaluated by the Z-scan technique using a He-Ne laser beam (632 nm). Results showed that the nonlinear refraction index (n(2) similar to 10(-6) cm(2)/w) and nonlinear absorption coefficient (beta similar to 10(-1) cm/w) of the prepared Ag/PVP nanocomposite thin film are higher than the previously reported values. A weak thermal optical nonlinearity was also observed and the nonlinear response dominantly resulted from the electronic origin.