Modulation of nonlinear optical properties in CdS based core shell nanocolloids fostered by metal nanoparticles

Abstract

Synthesis of core–shell nanocomposites and exploration of its nonlinear optical properties is significant in the field of nanophotonics. Here we address the enhanced nonlinear optical properties of Ag/Au-CdS nanocolloids with Ag or Au as core and CdS as shell, synthesized by pulsed laser ablation. The composite nanocolloids were prepared by the ablation of metal targets immersed in CdS colloidal solution. The third order optical nonlinearities of Ag/Au-CdS core-shell nanoparticles (NPs) were studied using Z-scan technique. The studies reveal that the nonlinear absorption (NLA) of the prepared core–shell nanoparticles exhibits reverse saturable absorption (RSA) property and excellent optical limiting (OL) behavior as compared to their individual counterparts. An overall enhancement in the optical nonlinearities could be observed with the core-shell nanocolloids with the incorporation of metal NPs. Strong exciton plasmon interaction and the local field enhancement from the metal NPs are considered as the dominant mechanisms behind the enhanced NLO properties of core shell nanocolloids. The observed nonlinear optical (NLO) properties and the calculated nonlinear optical coefficients suggests that these nanocomposites could be applied for various photonic and optical limiting applications.