近日，中山大学的周张凯及其研究团队取得一项新进展。经过不懈努力，他们基于任意复振幅控制实现超表面中轨道角动量和波长的复用操纵。相关研究成果已于2024年4月28日在国际知名学生期刊《光：科学与应用》上发表。

据悉，轨道角动量（OAM）因其无界和正交模式特性，被视为未来超高容量和超高速度信息处理中不可或缺的关键光学自由度（DoF）。尽管基于超表面的OAM操纵已在多个领域取得显著成果，但当前这种操纵主要局限于单自由度层面，即OAM与其他光学DoFs之间的多路复用操纵尚未实现，这极大地限制了OAM光束的广泛应用及超表面的进一步发展。

为了应对这一挑战，该研究团队提出了超表面的多路复用相干像素（MCP）理念。该方法能够在平面波和轨道角动量（OAM）波入射光下实现对任意复振幅的精准控制，并基于此实现了OAM和波长的多路复用DoF控制。因此，MCP方法扩展了可由超表面同时响应的入射光类型，丰富了超表面的信息处理能力，还为信息加密和OAM解复用器等应用创造了新可能。此项研究不仅为高安全性和高容量的超表面设计提供了重要工具，而且提升了OAM的控制和应用水平，为未来的多功能纳米光子器件研发展现了巨大潜力。

附：英文原文

Title: Multiplexed manipulation of orbital angular momentum and wavelength in metasurfaces based on arbitrary complex-amplitude control

Author: He, Guoli, Zheng, Yaqin, Zhou, Changda, Li, Siyang, Shi, Zhonghong, Deng, Yanhui, Zhou, Zhang-Kai

Issue&Volume: 2024-04-28

Abstract: Due to its unbounded and orthogonal modes, the orbital angular momentum (OAM) is regarded as a key optical degree of freedom (DoF) for future information processing with ultra-high capacity and speed. Although the manipulation of OAM based on metasurfaces has brought about great achievements in various fields, such manipulation currently remains at single-DoF level, which means the multiplexed manipulation of OAM with other optical DoFs is still lacking, greatly hampering the application of OAM beams and advancement of metasurfaces. In order to overcome this challenge, we propose the idea of multiplexed coherent pixel (MCP) for metasurfaces. This approach enables the manipulation of arbitrary complex-amplitude under incident lights of both plane and OAM waves, on the basis of which we have realized the multiplexed DoF control of OAM and wavelength. As a result, the MCP method expands the types of incident lights which can be simultaneously responded by metasurfaces, enriches the information processing capability of metasurfaces, and creates applications of information encryption and OAM demultiplexer. Our findings not only provide means for the design of high-security and high-capacity metasurfaces, but also raise the control and application level of OAM, offering great potential for multifunctional nanophotonic devices in the future.

DOI: 10.1038/s41377-024-01420-6

Source: https://www.nature.com/articles/s41377-024-01420-6