采用微球自组装及倾斜真空热蒸镀技术制作了三维手性壳状银纳米结构,采用Z扫描技术研究了该样品在532nm波长、4ns脉宽的Nd:YAG 激光入射下的非线性饱和吸收特性。研究结果表明,当入射激光强度达到 2.5×109 W/cm2时,其非线性吸收系数可达-1.45×10-5 cm/W,该结果比文献报道的悬浮液中的胶体银纳米颗粒的非线性吸收系数(-1.5×10-9 cm/W)大四个数量级。实验还发现,该样品的非线性吸收系数随着入射激光的偏振方向改变而出现明显的变化。文中对其非线性吸收的增强机理及偏振依赖性进行了分析讨论。

Three-dimensional chiral shell-like silver nanostructures are fabricated by micro-sphere self-assembly and tilted vacuum thermal deposition techniques,and the nonlinear saturation absorption characteristics of the sample are investigated by Z-scan technique with 4ns pulsed Nd:YAG laser at 532 nm wavelength.Our results show that when the irradiation intensity reaches to 2.5×109 W/cm2,the derived nonlinear absorption coefficient β can achieve to -1.45×10-5 cm/W,which is four orders of magnitude larger than the nonlinear absorption coefficient -1.5×10-9 cm/W of colloidal silver nanoparticles in suspensions.We also found that the nonlinear absorption coefficient of the silver nanostructure changes significantly with the polarization direction of incident light.The enhancement mechanism and polarization dependence of the nonlinear absorption are analyzed and discussed.