基于介质超材料的太赫兹偏振和相位控制  

Terahertz polarization and phase control using dielectric metamaterials

作　　者：张学迁[1] 张慧芳[1] 田震[1] 谷建强[1] 欧阳春梅[1] 路鑫超[2] 韩家广[1] 张伟力[1,3] 

机构地区：[1]天津大学精密仪器与光电子工程学院,光电信息技术科学教育部重点实验室,天津大学太赫兹波研究中心,天津300072 [2]中国科学院微电子研究所,北京100029 [3]美国俄克拉荷马州立大学电气与计算机工程系,俄克拉荷马74078

出　　处：《光电子．激光》2015年第11期2133-2140,共8页Journal of Optoelectronics·Laser

基　　金：国家重点基础研究发展计划(2014CB339800);高等学校博士学科点专项科研基金资助课题(20110032120058);国家自然科学基金(61427814,61138001,61205098,和61422509)资助项目

摘　　要：采用基于介质高阻硅超材料,设计了太赫兹（THz）波段高效率（〉64%）宽带的偏振转换器,并介绍了利用该器件控制相位的方法。采用8个不同尺寸的介质微结构作为控制相位的基本单元,通过恰当地排布它们的空间位置,设计了一个高效率、超宽带的THz波异常偏折器,其有效工作带宽范围为0.75~1.50THz,在1.25THz处效率最高可达70%以上,且偏折角度与频率相关,符合广义斯涅尔定律的描述。实验中,采用了自主搭建的角度分辨的光纤化THz时域频谱系统对设计的器件进行了表征,实验结果和仿真模拟及理论预测结果非常吻合。这种基于介质超材料的方法,克服了传统金属超材料中欧姆损耗的问题,且设计简单,加工方便。A high efficiency（64%）,broadband terahertz（THz）polarization converter is designed by employing a dielectric metamaterial made from high-impedance silicon.The working principle can be related to that of a traditional half waveplate.More interesting,such a dielectric metamaterial can also be applied in controlling the output phase of the cross-polarized wave.On the basis of such a device,8different dielectric structure unit cells are selected from numerous simulations for realizing the phase control.By properly engineering the spatial arrangement of these unit cells to form a linear phase profile at the interface,a high efficiency,broadband terahertz anomalous deflector is further designed.The effective working frequency range covers 0.75 THz to 1.25 THz with the highest deflection efficiency of more than 70%at 1.25 THz,which is much stronger than that of its metallic single-layer metamaterial counterpart（10%）.Meanwhile,the deflection angle is strongly related to the frequency,obeying the generalized Snell′s law.To experimentally characterize the proposed device,an angle-resolved,fiber-based terahertz time-domain spectrometer is employed.The experimental results show a good agreement with the simulation and theoretical prediction.Such dielectric metamaterials overcome the intrinsic ohmic loss problem of conventional metallic metamaterials,and are also very easy to design and fabricate.

关 键 词：超材料 介质微结构 偏振转换 相位不连续 太赫兹时域光谱 

分 类 号：O433[机械工程—光学工程]