Opt Lett. 2019 Apr 1;44(7):1556-1559. doi: 10.1364/OL.44.001556.
Reflective multichannel metasurfaces are flat reflectors that can control incident and reflected waves in a number of propagating directions simultaneously. However, they are always densely discretized with a high spatial resolution, which increases the manufacturing complexity. In this Letter, to the best of our knowledge, a new method that combines the array antenna theory with the metagratings theory is proposed. We demonstrate that the unit cells with a linear gradient phase in each period of the metasurfaces can eliminate specific space harmonics. With this method, multichannel metasurfaces can be designed with sparse unit cells, and high efficiency is maintained simultaneously. As proofs of the method, we design three different terahertz multichannel metasurfaces with no more than three unit cells per period. The simplification of structures can efficiently reduce the manufacturing complexity. This work may open up new routes in designing multichannel metasurfaces.
反射式多通道超表面是一种平面反射器，可同时控制多个传播方向的入射波和反射波。然而，它们总是高度离散化，具有很高的空间分辨率，这增加了制造的复杂性。在本信中，据我们所知，提出了一种将阵列天线理论与超光栅理论相结合的新方法。我们证明了在超表面的每个周期中具有线性梯度相位的单元可以消除特定的空间谐波。通过这种方法，可以设计具有稀疏单元的多通道超表面，同时保持高效率。作为该方法的证明，我们设计了三个不同的太赫兹多通道超表面，每个周期的单元不超过三个。结构的简化可以有效地降低制造的复杂性。这项工作可能为设计多通道超表面开辟新途径。
