Pu Mingbo, Li Xiong, Ma Xiaoliang, Wang Yanqin, Zhao Zeyu, Wang Changtao, Hu Chenggang, Gao Ping, Huang Cheng, Ren Haoran, Li Xiangping, Qin Fei, Yang Jing, Gu Min, Hong Minghui, Luo Xiangang
State Key Laboratory of Optical Technologies on Nano-Fabrication and Micro-Engineering, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China.
Centre for Micro-Photonics and CUDOS (Centre for Ultrahigh Bandwidth Devices for Optical Systems), Faculty of Science, Engineering and Technology, Swinburne University of Technology, P.O. Box 218, Hawthorn, Victoria 3122, Australia.
Sci Adv. 2015 Oct 2;1(9):e1500396. doi: 10.1126/sciadv.1500396. eCollection 2015 Oct.
The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a "true mathematical and mechanical form" in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer.
悬链线是一条自由悬挂的链条在自身重力作用下所呈现的曲线，17世纪70年代罗伯特·胡克认为它在建筑中是一种“真正的数学和力学形式”，然而在光学领域并未观察到显著现象。我们表明，光学悬链线可作为超表面的独特构建模块，以产生覆盖[0, 2π]的连续线性相移，这一任务对于现有技术而言即便并非不可能，也是极其困难的。通过悬链线阵列，设计并通过实验表征了平面光学器件，以产生携带轨道角动量（OAM）的各种光束。这些器件可在超宽带光谱中运行，因为与自旋 - 轨道相互作用相关的各向异性模式几乎与入射光频率无关。通过结合光学和拓扑特性，我们的方法将能够在单个纳米层内实现对光子的完全控制。
