Size-dependent enhancement of nonlinear optical properties in nanocolloids of ZnO

Abstract

We have investigated the third-order nonlinearity in ZnO nanocolloids with particle sizes in the range 6–18 nm by the z-scan technique. The third-order optical susceptibility ${\chi }^{\left(3\right)}$ increases with increasing particle size $\left(R\right)$ within the range of our investigations. In the weak confinement regime, an $R^2$ dependence of ${\chi }^{\left(3\right)}$ is obtained for ZnO nanocolloids. The optical limiting response is also studied against particle size.