基于超表面的阵列光场纵向维度信息编解码  

Longitudinally Encoding and Decoding Information in Light Field Arrays Based on Metasurface

作　　者：樊鑫豪 武炫光 周亮 刘圣 赵建林 李鹏 Fan Xinhao;Wu Xuanguang;Zhou Liang;Liu Sheng;Zhao Jianlin;Li Peng(Key Laboratory of Light Field Manipulation and Information Acquisition,Ministry of Industry and Information Technology,Shaanxi Province Key Laboratory of Optical Information Technology,School of Physical Science and Technology,Northwestern Polytechnical University,Xi'an 710129,Shaanxi,China)

机构地区：[1]光场调控和信息感知工业和信息化部重点实验室,陕西省光信息技术重点实验室,西北工业大学物理科学与技术学院,陕西西安710129

出　　处：《中国激光》2023年第18期188-194,共7页Chinese Journal of Lasers

基　　金：国家重点研发计划(2022YFA1404800);国家自然科学基金(12174309,12074312,12074313);博士论文创新基金(CX2022076)。

摘　　要：随着大数据时代的到来,空间光通信已被广泛应用于各种通信系统中,但随之而来的是容量瓶颈的挑战。基于光场频率、时间、偏振、横向空间模式等维度调控的信息编解码方法在解决容量问题方面展现了优异性能,但光场的纵向维度却未被应用于信息编解码。针对此问题,本文提出了一种基于电介质超表面的光场纵向维度信息编解码新方法,基于四原子结构的几何相位和传输相位联合调控,实现了透射场自旋相关的复振幅调控。同时,利用光学冻结波原理产生了轨道角动量模式叠加态的纵向可控变化,并验证了光场模态的纵向调控能够以指数级提升信道中的模态容量。纵向维度作为一个全新的编码自由度,有望进一步提高自由空间光通信性能。Objective Free-space optical communication,which uses a laser as an information carrier,is a wireless communication technology that is widely used in various communication systems.Owing to sufficient parametric dimensions,a series of new technologies have been developed to enhance optical communication capacity based on light field modulation.However,in recent years,with the exhaustion of these traditional dimensional resources and the advent of the big data era,optical communication is once again facing the challenge of a capacity crisis.In response,spatial structures(modes)of light fields are gradually being developed to address the growing capacity bottlenecks.For example,vortex beams carrying orbital angular momentum(OAM)have become an important breakthrough for sustainable capacity expansion of optical communications because their spatial modes are a new degree of freedom in constructing a high-dimensional Hilbert space.Consequently,various methods have emerged to encode information using the azimuthal order of OAM modes.Besides the azimuthal order multiplexing of OAM modes,the radial index and the vector modes are also used to achieve further information capacity enhancement.Although the spatial modes obtained based on the transverse modulation of light fields have fully demonstrated their feasibility in classical and quantum communications,another important spatial dimension of the light field,that is,the longitudinal dimension,has not been exploited for information encoding and decoding.Herein,we propose a dielectric metasurface for longitudinally modulating the superposition state of OAM modes and demonstrate the capability of these modulated light fields in information-encoding scenarios.The metasurface consists of tetratomic macropixels,which enable spin-dependent complex amplitude modulation of the transmitted field because of polarization-dependent interference and can produce a 5×5 light beam array with each beam channel presenting longitudinally variant superposition states of 0 to 15 orders.By in

关 键 词：表面光学 超表面 纵向调控 复振幅 编码 

分 类 号：O436[机械工程—光学工程]