Zhang Yuchao, Yang Xiaodong, Gao Jie
Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO, 65409, USA.
Sci Rep. 2018 Mar 20;8(1):4884. doi: 10.1038/s41598-018-23382-7.
Twisting light in both phase and intensity has recently drawn great interests in various fields related to light-matter interactions such as optical manipulation of particles and quantum entanglement of photons. Conventionally, bulky optical components are required to produce such twisted optical beams, which significantly limits their applications in integrated photonics and optical chips. Here, we design and demonstrate aluminum plasmonic metasurfaces consisting of nanoslit antennas as ultracompact beam converters to generate the focused twisted beams in both phase and intensity across the visible wavelength range. The metasurface is encoded with the combined phase profile containing the helico-conical phase function together with a Fourier transform lens based on the Pancharatnam-Berry (PB) geometric phase. It is demonstrated that the created twisted beams simultaneously possess three-dimensional (3D) spiral intensity distribution around the propagation axis and complex phase structure containing both the central vortex and the peripheral vortex string. Moreover, the twisted beam exhibits an arithmetic intensity spiral at the focal plane with the maximum photon concentration located at the leading point of the spiral. Our results show the promising potential for advancing metasurface-based integrated devices in many applications of light-matter interactions.
相位和强度都发生扭曲的光最近在与光-物质相互作用相关的各个领域引起了极大的兴趣，如粒子的光学操纵和光子的量子纠缠。传统上，需要庞大的光学元件来产生这种扭曲的光束，这极大地限制了它们在集成光子学和光学芯片中的应用。在此，我们设计并展示了由纳米狭缝天线组成的铝等离子体超表面，作为超紧凑的光束转换器，以在可见波长范围内产生相位和强度都聚焦的扭曲光束。该超表面编码有包含螺旋圆锥相位函数的组合相位分布以及基于潘查拉特纳姆-贝里（PB）几何相位的傅里叶变换透镜。结果表明，所产生的扭曲光束在传播轴周围同时具有三维（3D）螺旋强度分布以及包含中心涡旋和外围涡旋串的复杂相位结构。此外，扭曲光束在焦平面处呈现算术强度螺旋，最大光子浓度位于螺旋的前端。我们的结果表明，在光-物质相互作用的许多应用中，推进基于超表面的集成器件具有广阔的前景。
