Geometric metasurface fork gratings for vortex-beam generation and manipulation
Geometric metasurface fork gratings for vortex-beam generation and manipulation
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DOI：
10.1002/lpor.201500259
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发表时间：
2016-03-01
影响因子：
11
通讯作者：
Cheah, Kok Wai
中科院分区：
文献类型：
--
作者：
Chen, Shumei;Cai, Yuan;Cheah, Kok Wai
近年来，具有轨道角动量的光涡旋光束因其在大容量光通信中的潜力而受到广泛关注。这种能力源于轨道角动量（OAM）的无界拓扑电荷，它为信息编码提供了无限的自由。产生涡旋光束的两种最常见的方法是通过叉形衍射光栅和螺旋相板。传统的螺旋相板需要复杂的三维制造，而新兴的超表面领域为产生任意轨道角动量的涡旋光束提供了一种平面的、简便的解决方案。在各种类型的超表面中，几何相位超表面在控制光和自旋控制波的传播方面显示出巨大的潜力。在这里，我们实现了一种新型的几何超表面叉形光栅，它无缝地结合了用于涡束产生的超表面相位板和用于控制波传播方向的线性相位梯度超表面的功能。因此，超表面叉形光栅能够同时控制光的自旋角动量和轨道角动量。
In recent years, optical vortex beams possessing orbital angular momentum have received much attention due to their potential for high-capacity optical communications. This capability arises from the unbounded topological charges of orbital angular momentum (OAM) that provide infinite freedoms for encoding information. The two most common approaches for generating vortex beams are through fork diffraction gratings and spiral phase plates. While realization of conventional spiral phase plate requires complicated 3D fabrication, the emerging field of metasurfaces has provided a planar and facile solution for generating vortex beams of arbitrary orbit angular momentum. Among various types of metasurfaces, the geometric phase metasurface has shown great potential for robust control of light-and spin-controlled wave propagation. Here, we realize a novel type of geometric metasurface fork grating that seamlessly combine the functionality of a metasurface phase plate for vortex-beam generation, and that of a linear phase gradient metasurface for controlling the wave-propagation direction. The metasurface fork grating is therefore capable of simultaneously controlling both the spin and the orbital angular momentum of light.[GRAPHICS].