Research On Spatial Distribution Of Light Scattering Characteristics Of The Periodic Nano-structure

The periodic nano-structure is formed on the surface of sapphire after ion etching. The research of spatial distribution of light scattering characteristics of the periodic nano-structure is important to improve the optical properties and guide the actual measurement. So the thesis focuses on the periodic nano-structure and mainly researches their geometrical structure and spatial distribution of light scattering.The thesis mainly discusses the advantages and disadvantages of six different calculation methods of light scattering, sets up a reliable FEM-based analyzing model, and defines the parameters of the model, variable and boundary condition. In the end, spatial distribution of light scattering of the periodic nano-structure is simulated for one dimensional and two dimensional, and the influence of different factors on Scattering distribution is analyzed.The main research work include the following.1、The validity of the modeling method is demonstrated through two practical calculation cases based on finite element method (FEM), which fully shows that then study is reliable.2、The one-dimensional periodic nano-structure of TE and TM wave scattering field distribution characteristics is researched. When the incident Angle is close to π/5, the distribution of scattering field is circular for TE wave and fringe pattern for TM wave. When the incident angle is close to 0° or π/2, scattering field distribution of two wave is similar. At the same Angle of incidence, it can be arrived that the sum of the reflection coefficient and transmission coefficient is a fixed value. At the same time, analysis of the semicircle, triangle, rectangle of TE and TM wave scattering field distribution shows that the distribution of three kinds of shape is similar, but the electric field of rectangle, semicircle is larger and triangle is smaller.3、The two-dimensional periodic nano-structure is researched, and the plane scattering distribution of two mutually perpendicular is acquired. When the polar angle and azimuth angle of incident change, for one plane, the intensity of scattering field change from weakening to enhancement.When reach a certain angle, the intensity start to drop off. When the polar angle and azimuth angle of incident reach to π/4, the distribution of scattering field is circular. For another plane, the scattering of electric field is horizontal fringe pattern, and the location of strongest points of vertical scattering field is change. Studies have shown that absorption cross section, scattering cross section and extinction of section have close dependent on the polar angle of incident, but the impact on azimuth angle is small.