Zhang Di, Ren Mengxin, Wu Wei, Gao Ninghui, Yu Xuanyi, Cai Wei, Zhang Xinzheng, Xu Jingjun
Opt Lett. 2018 Jan 15;43(2):267-270. doi: 10.1364/OL.43.000267.
Beam splitters are essential components in various optical and photonic applications, for example, interferometers, multiplexers, and so on. Present beam splitters based on cubes or plates are normally bulky. Realizing beam splitters in nanoscales is useful to reduce the total size of photonic devices. We demonstrate here a beam splitter with nanoscale thickness based on a gradient metasurface comprising lithium niobate cylinder arrays. Since one unit cell of metasurface comprising two cylinder rows shows two opposite phase gradients, the incident light is split into different directions according to the generalized Snell's law. The split ratio is proven to be effectively tunable.
分束器是各种光学和光子应用中的关键组件，例如干涉仪、复用器等等。目前基于立方体或平板的分束器通常体积较大。实现纳米尺度的分束器有助于减小光子器件的整体尺寸。我们在此展示一种基于包含铌酸锂圆柱阵列的梯度超表面的具有纳米级厚度的分束器。由于包含两排圆柱的超表面的一个晶胞显示出两个相反的相位梯度，根据广义斯涅尔定律，入射光被分成不同方向。已证明分光比可有效调谐。
