Xin Jinhao, Du Zhiqiang, Zhou Zekai, Song Zhengyong
School of Electronic Science and Engineering, Xiamen University, Xiamen 361005, China.
Phys Chem Chem Phys. 2023 Oct 18;25(40):27008-27016. doi: 10.1039/d3cp02321d.
Due to the physically unrestricted set of orthogonally helical modes of orbital angular momentum (OAM), it has contributed significantly to wireless communication and information capacity. Meanwhile, focusing has important applications in fields such as super-resolution microscopic imaging and optical integration. Plasmonic metasurfaces have a powerful ability to modulate electromagnetic (EM) waves, and diversified functionalities in them are strongly desired. As of today, few plasmonic metasurfaces are reported which have multi-function in a single flat device. Herein, by fine-tuning the geometric dimensions and orientation angle of the meta-atom, the geometric phase is combined with the propagation phase to produce an independent phase response when left-handed circular polarization (LCP) and right-handed circular polarization (RCP) waves illuminate the metasurface. This paper presents three plasmonic metasurfaces, and each of them implements multiple functions on a single plasmonic metasurface. Firstly, normal reflection of OAM and a focused beam is achieved. Secondly, we realize anomalous reflection of OAM by convolving a gradient sequence and implement computational focusing at any point. Finally, addition theorem is adopted to implement the above two functions, and this design contains normal and inclined output beams. Our work provides novel approaches for the integration of multifunctional EM modulation.
由于轨道角动量（OAM）的正交螺旋模式在物理上不受限制，它对无线通信和信息容量有显著贡献。同时，聚焦在超分辨率显微成像和光学集成等领域有重要应用。表面等离激元超表面具有强大的调制电磁波（EM）的能力，人们强烈期望其具有多样化的功能。截至目前，很少有报道称单个平面器件中的表面等离激元超表面具有多功能。在此，通过微调超原子的几何尺寸和取向角，当左旋圆极化（LCP）和右旋圆极化（RCP）波照射超表面时，将几何相位与传播相位相结合以产生独立的相位响应。本文提出了三种表面等离激元超表面，并且每个超表面都在单个表面等离激元超表面上实现了多种功能。首先，实现了OAM的正反射和聚焦光束。其次，通过卷积梯度序列实现了OAM的反常反射，并在任意点实现了计算聚焦。最后，采用加法定理实现上述两种功能，并且这种设计包含正输出光束和倾斜输出光束。我们的工作为多功能电磁调制的集成提供了新方法。
