中文摘要：

光入射到不同折射率材料的分界面时会很自然地产生反射现象。在很多的工业应用中，例如太阳能电池，衬底的引入会在其表面产生反射损耗。至今为止，人们提出很多方法用来克服这一问题，比较常见的有介质涂层、表面纹理、绝热折射率匹配和散射等离激元纳米粒子。本文利用二维周期排布的亚波长级硅纳米圆柱阵列来降低衬底表面的反射。结合辅助微分方程和时域有限差分法对该结构的散射特性进行系统研究，结果发现，纳米圆柱粒子能够产生类似于在金属表面发生的超传输现象，这种现象的发生基于介质衬底耦合Mie共振机理，该机理能在整个紫外到近红外光谱范围内将能量耦合到衬底中，从而降低衬底表面的反射；同时当散射结构被放置在具有高光学态密度的高折射率衬底附近时，会产生较强的前向散射，也能有效的减少后向散射即反射的发生。基于降低衬底表面反射这一目的而言，我们设计的结构可为实际太阳能电池及光学天线的设计提供参考。

英文摘要：

Reflection is a natural phenomenon that occurs when light passes the interface between materials with different refractive index. In many applications, such as solar cells, introduction of a substrate will result in an increase in reflection. There are many ways to reduce the reflection from a substrate, which have been investigated so far, including dielectric interference coatings, surface texturing, adiabatic index matching, and scattering from plasmonic nanoparticles etc. Here we present an entirely new concept to eliminate reflection from a silicon wafer, which makes use of much simpler method than the ones reported before, and can be applied to any high-index material. Finite-difference-time-domain （FDTD） method and auxiliary differential equations are used in this paper to simulate a new structure that can suppress the reflection of light from a silicon surface over a broad spectral range. A two-dimensional periodic array of subwavelength silicon nanocylinders is designed, which possesses a phenomenon strongly substrate-coupled to the Mie resonances, and which can produce an extraordinary transmission phenomenon similar to the metal surface plasmon that yields almost zero total reflectance over the entire spectral range from ultraviolet to near-infrared. This new antireflection concept relies on the strong forward scattering that occurs when a scattering structure is placed in close proximity to a high-index substrate with a high optical density of states. For a detailed description of the problem, we have carried out some simulations. From the results, one can see that although nano-pillar covers only 30%of the substrate surface area, it can reduce the reflection from the surface from 30%to under 10%at the Mie resonance. For the purpose of reducing reflection from the substrate, this new structure designed may provide a reference for the actual solar cells and optical antenna design.