基于柔性超构材料宽带调控太赫兹波的偏振态  

Broadband modulation of terahertz wave polarization states with flexible metamaterial

作　　者：陈乐迪 范仁浩 刘雨 唐贡惠 马中丽 彭茹雯[1] 王牧[1] Chen Le-Di;Fan Ren-Hao;Liu Yu;Tang Gong-Hui;Ma Zhong-Li;Peng Ru-Wen;Wang Mu(National Laboratory of Solid State Microstructures,School of Physics,Nanjing University,Nanjing 210093,China)

机构地区：[1]南京大学物理学院,固体微结构物理国家重点实验室,南京210093

出　　处：《物理学报》2022年第18期337-347,共11页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61975078,11974177);国家重点研发计划(批准号:2017YFA0303702)资助的课题。

摘　　要：基于柔性超构材料从理论和实验两方面研究其对太赫兹波偏振态的宽带调控.首先以空间对称性破缺的L型金属-介质-金属结构为基本单元,构造出太赫兹手性超构材料.当太赫兹波与其相互作用时会产生一系列电偶极子,其时间响应可通过改变复合结构的几何参量来有效地调控,进而实现太赫兹波从线偏振态到圆偏振态的宽带高效转换.理论分析表明该手性超构材料中电偶极子的辐射随着入射角变化基本保持不变,从而利用该太赫兹手性超构材料可以构造能产生圆偏振态的柔性太赫兹波片,基于等效电路模型给出了该柔性太赫兹波片在弯曲情况下的工作原理.实验上,以柔性聚合物为介质层,利用光刻等微加工技术制备出基于该超构材料的柔性太赫兹波片,结果表明当线偏振太赫兹波入射到样品时,该样品能够在0.46—0.62 THz宽带范围内实现由线偏振态到圆偏振态的高效转换,同时在弯曲程度不同的情况下出射波均能保持稳定的圆偏振态.这种基于柔性超构材料来宽带调控太赫兹波偏振态的方案将有望应用于6G通信、分子探测等领域.In this work,we study the broadband manipulation of polarization states of terahertz(THz)waves with flexible metamaterial both theoretically and experimentally.Firstly,we construct a chiral THz metamaterial with asymmetric L-shaped metal-dielectric-metal structure,generating a series of electric dipoles via its interacting with terahertz waves.By changing the geometric parameters of the structure,the time responses of the electric dipoles in the two orthogonal directions are effectively modulated.Consequently,the chiral metamaterial efficiently converts linearly polarized terahertz wave into a circularly polarized one.The radiation of the metamaterial remains almost unaffected by the changing of the incident angle,which indicates that this chiral metamaterial can be used to realize a flexible terahertz circularly-polarized wave plate.Further,we present the working principle of this flexible terahertz circularly-polarized wave plate at the bending state based on the equivalent circuit model.Moreover,we fabricate a flexible metamaterial wave plate by using polymers as the dielectric layer.When the linearly polarized light is incident on the metamaterial,the circularly polarized output can be achieved in a wide frequency range of 0.46–0.62 THz.The polarization conversion remains quite stable even if the sample is bent.This flexible terahertz metamaterial wave plate is expected to be applied to 6G communication,molecular detection,etc.

关 键 词：超构材料 宽带圆偏振态 太赫兹波 柔性 

分 类 号：O441.4[理学—电磁学] TB34[理学—物理]