Thermo optical response in Ag and Au nano colloid prepared by laser ablation

Nonlinear and thermo optical properties of the gold and silver nanocolloids were investigated using CW Z -scan experiments. Sign of nonlinear refraction coefficient of colloids are negative at this condition. Negative sign implying thermal self defocusing is the most important mechanism of nonlinearity in our experiments. Diffraction pattern shows that nonlinear refraction of gold nano colloid must be at least 3 times greater. The linear and nonlinear absorption coefficient of gold nano colloid and silver nano colloid is determined to be 0. 9 cm-1 , 2.3 * 10-3 cm/w and 0.22 cm-1 , 1.9 * 10-4 cm/w respectively . These values produce temperature changes of about 90 K in gold nano colloid and 10 K in silver nano colloid at focus. Thermo optical constants of samples are determined at low and high temperature changes at focus

Keywords:

Thermo-Optics , SPM , Z-Scan , laser ablation