基于几何相位的太赫兹编码超表面反射器研制与测试  

Encoding terahertz metasurface reflectors based on geometrical phase modulation

作　　者：姜在超 宫正 钟芸襄 崔彬[1,2] 邹斌 杨玉平[1,2] Jiang Zai-Chao;Gong Zheng;Zhong Yun-Xiang;Cui Bin;Zou Bin;Yang Yu-Ping(School of Science,Minzu University of China,Beijing 100081,China;Engineering Research Center of Photonic Design Soft Wave,Ministry of Education,Beijing 100081,China)

机构地区：[1]中央民族大学理学院,北京100081 [2]光子系统工程软件教育部工程研究中心,北京100081

出　　处：《物理学报》2023年第24期322-331,共10页Acta Physica Sinica

基　　金：国家重点研发计划(批准号:2020YFB2009303,2017YFB00405402);国家自然科学基金(批准号:62075248)资助的课题。

摘　　要：基于几何相位的编码超表面对太赫兹(THz)波的偏振状态进行多维度、多自由度调控,具有重要的应用前景.本文提出了一种由反“S”形状的金属图案编码粒子构建的超表面,垂直入射情况下,在0.50—1.80 THz范围内的太赫兹波振幅反射率高于80%;结合Pancharatnam-Berry几何相位理论,通过旋转所设计单元的角度,获得8种编码粒子,设计了3种不同序列排布的1-bit,2-bit和3-bit编码超表面,并操控反射THz波分别产生不同角度的分束和偏折.此外,采用正入射和变角度的THz时域光谱仪分别对各个编码子单元结构阵列的反射特性(包括振幅反射率、相位、相位覆盖范围等)和设计的2-bit超表面的角度偏折现象进行测试;对比理论数值、模拟结果和实验结果,分析理论数值和实验数值之间存在偏差的原因,对满足实际需求的超表面逆向设计具有一定的借鉴意义.Multi-dimension and multi-freedom modulation of polarization state based on the geometrical-phase periodic encoding metasurface has important application prospects.Here,terahertz metasurface composed of specially shaped metal pattern coded particles is proposed.When the coded particles are normally incident,the amplitude reflectivity of the terahertz wave is above 80%in a range of 0.50-1.80 THz.Combined with the Pancharatnam-Berry(P-B)phase theory,8 kinds of coded particles are designed by rotating the angle of the designed unit.Three kinds of 1-bit,2-bit,and 3-bit periodic encoding metasurfaces with different encoding sequences are used to manipulate the reflected terahertz waves splitting into multiple-beam with different deflection angles.In addition,both reflection characteristics(including amplitude,phase,and phase coverage)of all coded particles and the angle deflection of the designed 2-bit periodic metasurface are measured by normal incidence THz time-domain spectrometer and variable incident angle THz time-domain spectrometer,respectively.Based on generalized Snell law and experimental results,the reason for the discrepancy between theoretical value and experimental value is further analyzed,which can provide a reference for the reverse design of the coded metasurfaces to meet various practical needs.

关 键 词：太赫兹波 Pancharatnam-Berry相位 编码超表面 操控 

分 类 号：O441.4[理学—电磁学]