A Research On Optical Properties Of New Nano-Structured System

With the demand trends of the scientific and technological progress as well as photonic devices miniaturization and integration, the emerging things of nanomaterials are attracting more and more attention. The main work of this paper can be divided into two aspects, one study based on the optical properties of nanocomposites, which is precious metal silver (Ag) nanoparticles attached to the semiconductor materials titanium dioxide (TiO2) nanowires. The other study is synthesize unique morphology of the precious metals silver nanoparticles by using innovative chemical method and preliminary study of their optical properties. The specific contents and innovations are listed as follows:1.TiO2nanowires with uniform morphology were prepared successfully by using a simple hydrothermal synthesis method. We found that the calcination time and the passed gas can greatly affect the morphology of the products. Then the TiO2nanowires of uniform appearance coated with a layer of Ag nano-spherical particles in the reduction of silver nitrate solution (AgNO3). We investigated the influence of coated concentration on the linear optical absorption properties of the products and found that the absorption peak was red-shifted with increasing the concentration of Ag nanoparticles. Meanwhile, the intensity of the peak was enhanced too. However, when the concentration of Ag nanoparticles continued to increase until it exceeded a certain threshold, the absorption peak of the contrary was a little blue shifted. We attribute these phenomenons to the effect of localized surface plasmon resonance of Ag nanoparticles.2. The nonlinear optical absorption properties of TiO2nanowires and the nanocomposites of TiO2nanowires coated with Ag nanoparticles were investigated carefully by using the Z-scan method and we obtained many peculiar results. Studies show that the nonlinear absorption coefficient changes significantly with the change of the incident light intensity. The nonlinear absorption of pure TiO2nanowires changes from a reverse saturable absorption to saturable absorption with the increasing of input light intensity. However, after coated with Ag nanoparticles, the nonlinear absorption of pure TiO2nanowires presents saturated absorption in any input light intensity and no reverse saturable absorption appear. These phenomenons can be ascribed to the two-photon absorption (TPA) process, is significantly inhibited when the Ag nanoparticles are coated on the TiO2nanowires.2. We investigated the photocatalysis properties of TiO2nanowires and the nanocomposites of TiO2nanowires coated with Ag nanoparticles under ultraviolet light and found that the photocatalytic property of TiO2nanowires was improved significantly by coating with Ag nanoparticles. Meanwhile, there is an optimum coated concentration of Ag nanoparticle which could make the photocatalytic efficiency of the as-prepared samples achieve the best.4, Several Ag nanoparticles, such as nanospheres and Micky shaped trimer, were synthesized by the chemical synthesis of independent innovation. We recorded the synthesis method, characterized the morphology, as well as preliminary studied of their linear and nonlinear optical properties. Experimental results showed that the as-prepared samples were morphology-smooth, well-structured, good-nature, and could provide a basis for further ultrafast optical experiments.