Nonlinear Optical Properties of Silver Nanoparticles Produced by Laser Ablation

Abstract

In this study, we investigated the production of silver nanoparticles by pulsed Nd: YAG laser ablation with λ=532nm in distilled water.The sodium citrate used to control the size of nanoparticles (Nps).The sample containing Ag NPs was characterized by linear absorption spectroscopy (UV-Visible spectroscopy) and transmission electron microscopy (TEM observation).The behavior of nonlinear optical properties of silver nanoparticles was studied using the Z-Scan method at two optimum numbers of the laser pulses and four optimum laser energy densities.In the Z-Scan method, the nonlinear thermal properties of Ag NPs were investigated under exposure to nanosecond laser pulse at λ=532nm.They were gained by fitting theoretical and experimental data.The values of the nonlinear refractive index ( ) and the nonlinear absorption coefficient () were compared concerning to two optimum numbers and four optimum energy densities.The results of the nonlinear refractive index showed a negative value for each sample, this means that samples act as a divergent lens, and the thermal self-defocusing effect can be the main factor of nonlinear behavior.Following the comparison of two quantities, and , we found that the nonlinear refractive index increased when the number of laser pulses light increased.In addition, the nonlinear absorption coefficient decreased when the number of laser pulses light increased.As a result, the application of these Ag NPs for optical switching devices was investigated, which demonstrated that the large Ag NPs are applicable tools for optical switching devices.