| The discovery of second harmonic generation revealed that nonlinear optical was born. Nanomaterials were famous for surface effect, small size effect and macroscopic quantum effect. Metal nanomaterials have some special properties. It shows surface plasmon resonance under the excitation of the light. The effect can cause localized surface plasmon resonance. The materials with large optical nonlinearity and ultrafast resonanse are the key to the preparation of ultrafast optoelectric device. And the surface plasmon resonance peak of silver nanoparticles is in the visible range, which attracts attention of scientists. Surface plasmon resonance effect can make the properties enhanced. The studies revealed that the quantity and position of surface plasmon resonance peak is related to the size and morphology of metal nanomaterials.In this thesis, silver nanoparticles with different sizes(3nm?10nm?30nm?100nm) were studied. Surface Plasmon resonance peaks were obtained to be 406nm?409nm? 413nm?449nm by measuring linear absorption. Firstly, the optical nonlinear absorption of silver nanoparticles with different sizes is researched under different energy by using nanosecond laser open Z-scan technology. We found that the 3nm silver nanoparticles show the reverse saturable absorption. While the silver nanoparticles with big size show the transformation from saturable absorption to reverse saturable absorption. Secondly, the optical nonlinear refraction of silver nanoparticles is investigated under different energy by using nanosecond laser closed Z-scan technology. We found that the silver nanoparticles with small size show the self-defocusing, and the silver nanoparticles with big size show the transformation from self-defocusing to self-focusing. Finaly, the ultrafast dynamic process of silver nanoparticles is researched by using femtosecond laser pump-probe technology. The characteristic relaxation time of silver nanoparticles is obtained by fitting the curves. |
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