Modulation of optical nonlinearity of silver nanoparticles by 2D ZnO nanoflakes

Abstract

In this study, we investigated the size- and shape-dependent optical nonlinearity of silver nanoparticles (AgNPs), and their modulation upon mixing with 2D ZnO nanoflakes (ZnONFs) using a Z-scan technique powered by a continuous-wave 514.5 nm Ar-ion laser source. We prepared three batches of AgNPs with varying average particle sizes of 36 nm, 64 nm, and 81 nm and one batch of ZnONFs, by employing chemical reduction and hydrothermal preparation protocols, respectively. Our experimental results revealed a decrease in the values of the nonlinear refractive index of AgNPs with an increase in their average sizes. It appeared that variation in the shape of the AgNPs does not have any appreciable impact on the optical nonlinearity. The value of the nonlinear refractive index of AgNPs amplified significantly upon mixing with ZnONFs. Interestingly, the magnitude of the enhancement of the nonlinear refractive index of AgNPs was found to be dependent on the proportion of both ZnONFs and AgNPs in the mixture. We could harvest ∼ 4 times larger magnitude of the nonlinear refractive index of AgNPs, by mixing 40 % of AgNPs with the lowest average particle size with 60 % of ZnONFs.

Keywords

• Silver nanoparticles (AgNPs)
• 2D ZnO nanoflakes
• Ar-ion laser (514.5 nm)
• Localized surface plasmon resonance (LSPR)
• and Z-scan technique