Ji Chen, Song Jiakun, Huang Cheng, Wu Xiaoyu, Luo Xiangang
Opt Express. 2019 Jan 7;27(1):34-44. doi: 10.1364/OE.27.000034.
Recently, considerable attention has been focused on orbital angular momentum (OAM) vortex wave, owing to its prospect of increasing communication capacity. Here, a single-layer metasurface is proposed to realize vortex beams with different OAM modes and polarizations carried at two distinctive bands. Both the resonant and geometric (Pancharatnam-Berry) phase cells are adopted to construct this metasurface for generating the desired phase profile, and each type of phase modulation cell can independently control the vortex beam at different frequencies. When a linearly-polarized wave is incident onto our metasurface, the resonant phase cells with spiral phase distribution can achieve OAM beam with topological charge of + 1 at 5.2 GHz. And under illumination of left-handed circular polarized (LHCP) wave, the rotated geometric phase cells assist the metasurface to generate the deflected OAM beam with topological charge of + 2 at 10.5~12 GHz. Both simulated and experimental results demonstrate good performance of the proposed single-layer metasurface at the above two frequency bands.
近年来，由于轨道角动量（OAM）涡旋波有望提高通信容量，它受到了广泛关注。在此，我们提出了一种单层超表面，以在两个不同频段实现携带不同OAM模式和偏振的涡旋光束。采用共振相位单元和几何（潘查拉特纳姆-贝里）相位单元来构建该超表面，以生成所需的相位分布，并且每种类型的相位调制单元都可以在不同频率下独立控制涡旋光束。当线偏振波入射到我们的超表面上时，具有螺旋相位分布的共振相位单元可以在5.2 GHz频率下实现拓扑电荷为 +1的OAM光束。而在左旋圆偏振（LHCP）波的照射下，旋转的几何相位单元辅助超表面在10.5~12 GHz频率下生成拓扑电荷为 +2的偏转OAM光束。模拟和实验结果均表明，所提出的单层超表面在上述两个频段具有良好的性能。
