Spin-Symmetry-Selective Generation of Ultracompact Optical Vortices in Nanoapertures without Chirality
Spin-Symmetry-Selective Generation of Ultracompact Optical Vortices in Nanoapertures without Chirality
复制标题
无手性纳米孔径中自旋对称选择性生成超紧凑光学涡旋
DOI：
10.1002/sstr.202000008
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发表时间：
2020
期刊：
影响因子：
15.9
通讯作者：
Sun Hong-Bo
中科院分区：
文献类型：
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作者：
Cui Tong;Zhang Mingqian;Sun Lin;Zhang Shuyin;Wang Jia;Bai Benfeng;Sun Hong-Bo
携带轨道角动量的纳米尺度光学涡旋(OV)可以通过纳米结构中的光子自旋-轨道相互作用(SOI)产生，在量子通信和光学操纵等新兴领域有着重要的应用。现有的OV产生器，如亚表面和手性结构，受到不连续波前调制、单自旋响应和体积尺寸的影响。高度对称结构中的光子SOI一直被忽视。此外，目前还没有关于纳米级OVS近场形成机理的实验研究。在这里，通过研究等离子体环形纳米孔中的SOI，报道了一种在纳米孔中产生超致密且无手性的OV和OV阵列的简单而可靠的方法。实验上证明了在6 × 6 m2的小面积内产生3 × μ3 OV阵列。利用自制的自旋选择和相分辨的近场显微系统，在自旋基础上，直接从近场到亚波长分辨率的远场探测产生的OV波前的动态演化，直观地揭示了SOI过程。这些发现为大规模、低成本的OV束产生提供了一种简单有效的解决方案，并为纳米级光子SOI的实验探索提供了强有力的工具。
Nanoscale optical vortices (OVs) carrying orbital angular momenta can be generated via photonic spin–orbit interaction (SOI) in nanostructures and have important applications in many emerging fields such as quantum communication and optical manipulations. Existing OV generators such as metasurfaces and chiral structures suffer from discontinuous wavefront modulation, single‐spin response, and bulk size. The photonic SOI in highly symmetric structures has been overlooked. Furthermore, there is no experimental study on the near‐field formation mechanism of nanoscale OVs. Here, by studying the SOI in a plasmonic annular nanoaperture, a simple and reliable way for generating ultracompact OVs and OV array in nanoapertures without chirality is reported. The generation of a 3 × 3 OV array within a small area of 6 × 6 μm2is demonstrated experimentally. Using a homemade spin‐selective and phase‐resolved near‐field microscopic system, in the spin basis, the dynamic evolution of the wavefront of the generated OV is directly probed from the near field to the far field with subwavelength resolution, which intuitively reveals the SOI process. The findings provide a simple and effective solution for large‐scale, low‐cost OV beam generation and offer a powerful tool for experimental exploration of the nanoscale photonic SOI.