Nonlinear optical properties of colloidal ZnO-Au nanostructures for optical limiting applications

The nonlinear response of zinc oxide and zinc oxide-gold hybrid colloidal nanostructures to 532 nm nanosecond pulses was investigated. The z-scan technique was used to measure the nonlinear absorption of zinc oxide, zinc-oxide: gold hybrids and mixed colloids of zinc-oxide and gold. Despite similar zinc oxide concentrations, the colloids containing gold nanoparticles displayed stronger intensity dependent nonlinear absorption with optical limiting thresholds for the three samples of 35 J/cm2, 6.1 J/cm2 and 4.1 J/cm2, respectively. Therefore, by combining gold with zinc-oxide to form hybrid nanostructures or by simply mixing gold and zinc-oxide nanostructures together, the optical limiting threshold is reduced which is advantageous for optical limiting applications.