Opt Lett. 2018 Sep 15;43(18):4350-4353. doi: 10.1364/OL.43.004350.
Beam splitters play important roles in several optical applications, such as interferometers, spectroscopy, and optical communications. In this study, we propose and numerically examine polarization-insensitive beam splitters utilizing two-step phase gradient all-dielectric metasurfaces in the visible spectrum. The metasurface is made of periodically arranged binary unit cells, and phase difference between neighboring unit cells on the surface is 180 deg. The metasurface is shown to have a special phase gradient whose sign changes periodically. The angle of the split beams on both sides and the corresponding total transmission value at 532 nm wavelength are found to be ±46.8° and 0.90, respectively.
分束器在干涉仪、光谱学和光通信等多种光学应用中发挥着重要作用。在这项研究中，我们提出并数值研究了利用在可见光波段的两步相位梯度全介质超表面实现的偏振不敏感分束器。超表面由周期性排列的二元单元组成，表面上相邻单元之间的相位差为 180°。超表面显示出一种特殊的相位梯度，其符号周期性变化。在 532nm 波长下，两侧分束角和相应的总透射值分别为±46.8°和 0.90。
