Optical Limiting Properties of Colloids Enhanced by Gold Nanoparticles Based on Thermal Nonlinear Refraction

In this work, thermo-optical properties of gold nanoparticle colloids are studied using continuous wave (CW) laser irradiation at 532 nm. The nanoparticle colloids are fabricated by 18 ns pulsed laser ablation of pure gold plate in the distilled water. The formation of the nanoparticles has been evidenced by optical absorption spectra and transmission electron microscopy. The nonlinear optical properties of gold nanoparticles colloids are investigated by closed Z-scan under irradiation of a low power CW laser. It will be shown that the thermal lens model is in excellent agreement with the experimental results of samples. The aperturelimitted optical limiters based on the nonlinear refraction of colloidal solution are presented. The tunability of limiting threshold of optical limiters can be accomplished by engineering of the experimental geometry.