Investigation of Third-Order Optical Susceptibility in ZnO/SnO2/Ag Ternary Composite Nanoparticles

Abstract

In this study, a two-step co-precipitation method has been utilized to synthesize Ag-loaded ZnO/SnO2 composite nanoheterojunctions. The obtained composite nanoparticles have been characterized using X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). Linear optical studies have been conducted by UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) and photoluminescence (PL) emission techniques. UV–Vis DRS results have indicated the enhanced absorption ability for Ag-loaded ZnO/SnO2 composites relevant to the surface plasmon resonance. PL analysis has shown a delay in the recombination rate of photoexcited electron–hole pairs due to the formation of the built-in internal electric field. The responses of composite samples to intense laser fields have been examined by a standard single-beam Z-scan technique under a 532-nm Nd:YAG laser as an excitation source. The nonlinear optical behaviors have been confirmed by the observation of the self-defocusing phenomenon due to the negative lens effect and reverse saturable absorption response owning to two-photon absorption processes. The measured value of the third-order nonlinear susceptibility for Ag-loaded ZnO/SnO2 composite nanoheterojunctions has been found to be 5.61 × 10–5 esu, presenting an increase about 2.4 times higher than that of sole ZnO/SnO2 nanoparticles (2.31 × 10–5 esu).