微纳粒子光学散射分析

为实现利用光学方式对微纳尺度粒子性质的研究,探讨了亚微米线及亚微米球对光电磁波的散射效应.微纳米尺度粒子的光学散射,散射粒子尺寸与入射光波长尺寸可满足米氏(Mie)散射条件.利用Matlab数值模拟的方式,将分析结果以模拟图的形式清晰地展现出来.满足尺寸条件的层状粒子以及任意多个散射粒子存在时对电磁波的散射都可采用Mie散射分析方法,并且针对多粒子散射,分析了散射体位于不同位置时对散射造成的影响.通过分析光学散射光场相关的微分散射截面及近场散射电磁场分布,可得出散射光场随散射角度的变化趋势,以及散射光场受各类因素的影响,包括入射光偏振态、散射粒子尺寸、散射粒子结构及粒子构成层数、散射粒子数量等的影响,也包括一些隐含因素对散射光场的影响,如散射粒子与周围介质的相对折射率.本文的科学意义体现在:与入射光波长尺寸可比的亚微米尺度的粒子,可用作传感器,对于其位移的探测可通过光学方式来实现,而由于粒子本身特性对散射光的影响具有一定的参考价值,从而使通过光学方式对机械位移的读出具有更高准确度.研究结果对于光学方式探测亚微米线机械振动具有指导意义.

Analysis of optical scattering of micro-nano particles

The micro-nano-scale science is rapidly developing. In order to study the properties of micro-nano-scale particles by the optical method, we discuss the scattering effects of sub-micrometer wires and sub-micrometer balls on photo-electromagnetic wave in this paper. For the optical scattering of micro-nano-scale particles, the scattering particle size can meet the Mie scattering conditions compared with the incident light wavelength, that is to say, the scatterer and the incident wavelength have comparable size. In this article, the analysis results are clearly displayed in the form of simulation graphs obtained by the Matlab numerical simulation. The Mie scattering analysis method can be used for discussing the scattering of electromagnetic waves in the cases of layered particles which meet the size requirements and any number of scattering particles. Multi-particle scattering is analyzed to investigate the effects of scatterers at different positions on the scattering. By analyzing the differential scattering cross section and the electromagnetic field distribution of near-field scattering related to the scattering light field, we obtain the variation trend of the scattering light field with scattering angle and the effects of various factors on the scattering light field, including the polarization of incident wave, the size of the scatterer, the structure of scattering particles, the number of particles, the number of scattering particles, and some hidden factors such as the relative refractive index of scatterer and surrounding medium. The scientific significance of the paper is reflected through the fact that the sub-micron scale particle can be used as a sensor of detecting the displacement, which can be realized by optical means. So it has a certain reference value for studying the influence of particle own characteristic on the scattering light, thereby rendering the optical readout of the mechanical displacement very accurate. The obtained results have a guiding significance for studying the optical detection of mechanical vibrations of sub-micron wires.