本文基于Mie散射理论,设计了三种(Au,Au-介质,介质-Au)球形纳米结构,并研究结构参数及周围环境对结构的光散射性质的影响。说明结构外半径的增加会使共振位置发生红移,线宽增加,并且偶极近似不再成立。经研究发现,在偶极近似下,Au-介质纳米核壳结构中核半径的增大使得散射峰增强,线宽也比金球颗粒的小。并且介质折射率的增加,会使散射峰进一步增强,并产生一定的红移。对于介质-Au纳米核壳结构,当Au层厚度较小的情况下,球模和腔模之间的强耦合作用使得共振峰位置发生较大的红移,散射峰也显著增强。并且随着介质核的折射率增加,会进一步使得模式发生红移。考虑到实际应用,最后通过在Au-介质纳米核壳结构的介质层引入增益,或者减小介质-Au纳米核壳结构半径,发现其均能在石英环境中实现可见光波段的窄带强散射。这些研究结果将对高性能透明显示屏的制备提供重要的理论依据。

Based on Mie scattering theory,we design three kinds of nanostructures (Au,Au-dielectric,dielectric-Au)and study the effects of the structure parameters and the background refractive indexes on optical scattering properties of nanostructures.It is demonstrated that by increasing the outer radius of the nanoparticle,the resonance position will show a redshift and the linewidth increases.In addition,the dipole approximation is no longer valid.Experimentally discovered that comparing with the results of the Au spherical nanoparticle,the scattering peak enhances and the linewidth becomes narrower as the increase of the core radius in Au-dielectric core-shell nanostructures under the dipole approximation.For the dielectric-Au core-shell nanostructure,it is found that when the thickness of Au layer decreases,the strong coupling between the spherical mode and the cavity mode makes the resonance peak position redshift and the scattering peak increase significantly.With the increase of the refractive index of the dielectric core or shell,the mode will be further red shifted for Au-dielectric or dielectric-Au core-shell nanoparticles.Finally,by introducing gains into the dielectric layers of the Au-dielectric core-shell nanoparticles or reducing the dielectric-Au core-shell nanoparticles in silica environment considering the practical application,the narrow-band and strong scattering in the visible range can be realized.These results will provide important theoretical basis for the fabrication of the high performance transparent display screens.