Preparation Of Silver/Zinc Oxide Core-shell Nanoparticles By Liquid-phase Laser Ablation And Its Nonlinear Optical Effect

The development of nonlinear optics is largely due to the emergence and application of new optical materials.In recent years,nonlinear optical materials have developed rapidly.In addition to conventional bulk materials,the discovery of microstructures has made the scope of nonlinear optical materials expanded to nanomaterials.Among them,core-shell nanomaterials have brought new opportunities for the development of nonlinear optics.Because core-shell nanoparticles have usually better performance than single metal nanoparticles,they have been widely used in electronics,optics,catalysis,and microelectronics.In the field of nonlinear optics,core-shell particles have become the focus of research because of their better nonlinear optical properties than those of single-component nanoparticles.This thesis mainly studies the nonlinear optical properties of Ag,ZnO nanoparticles and Ag@ZnO core-shell nanoparticles.The main novelties of this thesis are as follows:First,Ag,ZnO nanoparticles and Ag@ZnO core-shell nanoparticles were prepared using liquid-phase laser ablation at different ablation times;Second,the nonlinear refraction effects and nonlinear absorption effects of the three nanoparticles were studied by the use of closed-and open-aperture Z-scan techniques;Third,the variation of Ag@ZnO core-shell nanoparticles with different shell thickness were studied by using closed-and open-aperture Z-scan techniques.The main research contents of this thesis include:1.The liquid-phase laser ablation method and its mechanism,the preparation approaches of core-shell nanostructures,and their research status of nonlinear optics are introduced in detail.The Z-scan characterization technology is introduced,and the characteristics of the closed-and open-aperture Z-scan traces are analyzed.Taking the standard samples as examples,the Z-scan measurement system was calibrated with Cd S and CS₂,which proved the reliability and sensitivity of the Z-scan system.2.Adopting the liquid laser ablation method,the Ag,ZnO,and Ag@ZnO core-shell nanoparticles were fabricated and characterized.First,Ag,ZnO nanoparticles and Ag@ZnO core-shell nanoparticles were successfully prepared by liquid-phase laser ablation;Second,the morphology,crystal structure,optical properties and element distribution of the three nanoparticles prepared were characterized by transmission electron microscopy,X-ray diffractometer,UV-NIR visible absorption spectrum,and X-ray energy spectrometer,respectively.Then,the XRD images,TEM images and absorption spectra of core-shell nanoparticles were analyzed.Finally,the synthesis mechanism of core-shell nanoparticles was discussed.3.The nonlinear optics properties of Ag,ZnO nanoparticles and Ag@ZnO core-shell nanoparticles were studied.First,the magnitude of the nonlinear refractive index of three kinds of nanoparticles under the excitation of 800 nm femtosecond pulse was studied.Next,the intensity-dependent of the nonlinear refractive indexs of three kinds of nanoparticles were studied,and the reasons for the negligible nonlinear absorption effect of the three kinds of nanoparticles were analyzed.Then,the mechanism of nonlinear enhancement of core-shell nanostructures was analyzed.Finally,the application of core-shell nanoparticles in optical switches is discussed.4.The nonlinear optical properties of Ag@ZnO core-shell nanoparticles prepared under different ablation time were studied.First,Ag@ZnO core-shell nanoparticles with different shell thicknesses were synthesized by liquid-phase laser ablation at different ablation times;Second,the morphology,crystal structure and optical properties of the core-shell nanoparticles were characterized and analyzed using transmission electron microscope,X-ray diffractometer and ultraviolet-visible-near infrared absorption spectrum;Finally,the dependence of the third-order nonlinear refractive index of core-shell nanoparticles on the thickness of the shell under the excitation of femtosecond laser pulses at 800 nm was studied.