Laser-Ablation Synthesis and Evaluation of Thermal Non-Linear Optical Properties of Silver Nanoparticles in Monoolein

Abstract

Silver nanoparticles were prepared in monoolein, a glycerol derivative of oleic acid, via pulsed laser ablation of a silver plate with a Q-Switched Nd:YAG laser (1064 nm). The average size of the nanoparticles was 8.8 +/- 0.5 nm, with a narrow size distribution of 4.6 nm FWHM. No significant agglomeration or flocculation was observed after one-month storage. The observed results indicated a nonlinear dependence of the refractive index n(2) on the particle volume fraction. Furthermore, the monoolein-silver nanoparticle solution showed self-defocusing behaviour, as deduced from the negative sign in n(2) and spatial self-phase modulation, which depended on the volume fraction. Non-linear absorption behaviour was not observed in any of the samples analyzed. The results in this work suggest that colloidal silver nanoparticle solutions in monoolein are interesting nonlinear materials to create and control different spatial effects and that such silver-monoolein colloids might be used in a multitude of optical applications, such as spatial soliton propagation, real time holography, and liquid crystal-based applications.