ABSTRACT:

Silver and gold nanoparticles were synthesized using an aqueous extract from flower leaves of the Hibiscus tiliaceus as a reducer and stabilizer. The synthesized Ag and Au nanoparticles were characterized using many techniques such as UV– Vis spectroscopy to determine the surface Plasmon resonance (SPR) peak, transmission electron microscopy (TEM) to investigate the shape and the particle size distribution, X-ray diffractometer (XRD) to examine the crystallite size and crystalline nature of the nanoparticles, and Spectrofluorophotometer to record the fluorescence emission spectra. The optical nonlinearities of Ag and Au nanoparticles were investigated using z-scan technique with low power Argon laser beam at wavelengths 488 nm and 514 nm in continuous wave regime (CW), and at 532 nm in the Pulsed laser regime. The origin of nonlinearity were discussed. The obtained data showed that the process involved in the nonlinear absorption is reverse saturation absorption and negative nonlinear refractive index for Ag nanoparticles, whereas for Au nanoparticles the process involved in the nonlinear absorption is saturation absorption and negative nonlinear refractive index. The optical nonlinear properties of the synthesized Ag and Au nanoparticles were used to demonstrate optical limiting and all-optical switching. Ag and Au nanoparticles show potential capability to be used as optical limiters and as all-optical switching devices.