Bayati Elyas, Zhan Alan, Colburn Shane, Zhelyeznyakov Maksym Viktorovich, Majumdar Arka
Appl Opt. 2019 Feb 20;58(6):1460-1466. doi: 10.1364/AO.58.001460.
Sub-wavelength diffractive optics, commonly known as metasurfaces, have recently garnered significant attention for their ability to create ultra-thin flat lenses with a high numerical aperture. Several materials with different refractive indices have been used to create metasurface lenses (metalenses). In this paper, we analyze the role of refractive index on the performance of these metalenses. We employ both forward and inverse design methodologies to perform our analysis. We found that, while high-refractive-index materials allow for extreme reduction of the focal length, for moderate focal lengths and numerical aperture (<0.6), there is no appreciable difference in the focal spot size and focusing efficiency for metalenses made of different materials with refractive indices ranging between 1.2 and 3.43 in forward design, and 1.25 and 3.5 in inverse design.
亚波长衍射光学器件，通常称为超表面，最近因其能够制造具有高数值孔径的超薄平面透镜而备受关注。几种具有不同折射率的材料已被用于制造超表面透镜（超透镜）。在本文中，我们分析了折射率对这些超透镜性能的作用。我们采用正向和逆向设计方法来进行分析。我们发现，虽然高折射率材料能够极大地缩短焦距，但对于中等焦距和数值孔径（<0.6），在正向设计中，由折射率介于1.2和3.43之间的不同材料制成的超透镜，以及在逆向设计中由折射率介于1.25和3.5之间的不同材料制成的超透镜，其焦斑尺寸和聚焦效率没有明显差异。
