Ag@ZnO core–shell nanostructures, ZnO nanoparticles (NPs), and Ag NPs were synthesized by laser ablation in water using 8 ns, 1064 nm, and 50 mJ/pulse. The structural, morphological, componential, and optical properties of as-synthesized NPs were examined by X-ray diffraction, transmission electron microscopy, electron diffraction spectrum, and ultraviolet–visible absorption, respectively. The third-order nonlinear optical properties of aqueous dispersions of three NPs were characterized by performing Z-scan experiments with femtosecond laser pulses at 800 nm. It is shown that three NPs exhibit the positive refractive nonlinearity in the absence of nonlinear absorption and the third-order nonlinear refraction index increases in the order of NPs ZnO < Ag < Ag@ZnO. The results indicate that the Ag@ZnO core–shell nanostructure is a promising candidate for applications in ultrafast all-optical switching.

中文翻译：

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液相激光烧蚀制备Ag@ZnO核壳纳米结构及其飞秒非线性光学性质研究

Ag@ZnO 核壳纳米结构、ZnO 纳米颗粒 (NPs) 和 Ag NPs 是通过在水中使用 8 ns、1064 nm 和 50 mJ/脉冲的激光烧蚀合成的。分别通过 X 射线衍射、透射电子显微镜、电子衍射光谱和紫外-可见吸收来检查合成的 NPs 的结构、形态、成分和光学性质。通过使用 800 nm 的飞秒激光脉冲进行 Z 扫描实验，表征了三种纳米颗粒的水分散体的三阶非线性光学特性。结果表明，三个纳米颗粒在没有非线性吸收的情况下表现出正折射非线性，三阶非线性折射率以纳米颗粒 ZnO < Ag < Ag@ZnO 的顺序增加。