Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zo...Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization.Specifically,when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms,the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave.As function demonstrations,we have designed two types of metasurface zone plates:one is a focused linear polarizer,and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves.The simulated and measured results are consistent with theoretical expectations,suggesting that the proposed concept is flexible and feasible.Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.展开更多
If a metalens integrates the circular polarization(CP)conversion function,the focusing lens together with circular-polariz-ing lens(CPL)in traditional cameras may be replaced by a metalens.However,in terahertz(THz)ban...If a metalens integrates the circular polarization(CP)conversion function,the focusing lens together with circular-polariz-ing lens(CPL)in traditional cameras may be replaced by a metalens.However,in terahertz(THz)band,the reported metalenses still do not obtain the perfect and strict single-handed CP,because they were constructed via Pancharatnam-Berry phase so that CP conversion contained both left-handed CP(LCP)and right-handed CP(RCP)components.In this paper,a silicon based THz metalens is constructed using dynamic phase to obtain single-handed CP conversion.Also,we can rotate the whole metalens at a certain angle to control the conversion of multi-polarization states,which can simply manipulate the focusing for incident linear polarization(LP)THz wave in three polarization conversion states,in-cluding LP without conversion,LCP and RCP.Moreover,the polarization conversion behavior is reversible,that is,the THz metalens can convert not only the LP into arbitrary single-handed CP,but also the LCP and RCP into two perpen-dicular LP,respectively.The metalens is expected to be used in advanced THz camera,as a great candidate for tradi-tional CPL and focusing lens group,and also shows potential application in polarization imaging with discriminating LCP and RCP.展开更多
本文提出了一种"金属栅-开口环/硅环-金属栅"结构的透射式超表面偏振控制器,研究了入射角度和抽运光对该器件传输及偏振态控制性能的影响.研究结果表明,当线偏振太赫兹波垂直入射时,可对0.39—1.11 THz频段的太赫兹波实现偏...本文提出了一种"金属栅-开口环/硅环-金属栅"结构的透射式超表面偏振控制器,研究了入射角度和抽运光对该器件传输及偏振态控制性能的影响.研究结果表明,当线偏振太赫兹波垂直入射时,可对0.39—1.11 THz频段的太赫兹波实现偏振方向90?旋转,偏振旋转效率为99%,损耗为1 d B.对于斜入射的情况,偏振转换性能在0—60?范围内基本保持不变,且透过率达到90%以上.同时,通过调控抽运光强度的方式,该器件能够实现对透射与反射太赫兹光束的强度调制,调制深度均达到90%,且可以实现太赫兹波偏振分束功能.该器件可以作为未来太赫兹空间光通信和信息处理的宽带、角度不敏感、可调谐的偏振转换器和分束器.展开更多
基于漫反射和随机编码理论提出一种应用于雷达散射截面积(RCS)缩减的超表面,并通过仿真和实验进行验证。首先,简要阐述了漫反射和随机编码理论,并设计一种基于金属分割线结构的线极化转换超单元。该结构基于"0"、"1"...基于漫反射和随机编码理论提出一种应用于雷达散射截面积(RCS)缩减的超表面,并通过仿真和实验进行验证。首先,简要阐述了漫反射和随机编码理论,并设计一种基于金属分割线结构的线极化转换超单元。该结构基于"0"、"1"两种基本单元进行编码,在宽频段范围内实现180°反射相位差。仿真结果表明,超表面在6~14GHz频段内,线极化转换率高达90%,RCS缩减大于10 d B的带宽达到6 GHz。然后,设计三种随机编码超表面,进行制备和实验测试。实验结果表明:在5.5~13 GHz频带范围内,三种随机超表面在垂直入射时的反射率小于–10d B,存在6 GHz带宽RCS缩减大于10 d B,与仿真结果基本一致。另外,斜入射情况下,同样能得到有效的RCS缩减,随机编码超表面具备宽角度入射RCS缩减特性。该设计为雷达隐身技术提供了一种新的途径。展开更多
文摘Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization.Specifically,when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms,the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave.As function demonstrations,we have designed two types of metasurface zone plates:one is a focused linear polarizer,and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves.The simulated and measured results are consistent with theoretical expectations,suggesting that the proposed concept is flexible and feasible.Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.
基金supported by the National Natural Science Foundation of China(Nos.61675147,61735010 and 91838301)National Key Research and Development Program of China(No.2017YFA0700202)Basic Re-search Program of Shenzhen(JCYJ20170412154447469).
文摘If a metalens integrates the circular polarization(CP)conversion function,the focusing lens together with circular-polariz-ing lens(CPL)in traditional cameras may be replaced by a metalens.However,in terahertz(THz)band,the reported metalenses still do not obtain the perfect and strict single-handed CP,because they were constructed via Pancharatnam-Berry phase so that CP conversion contained both left-handed CP(LCP)and right-handed CP(RCP)components.In this paper,a silicon based THz metalens is constructed using dynamic phase to obtain single-handed CP conversion.Also,we can rotate the whole metalens at a certain angle to control the conversion of multi-polarization states,which can simply manipulate the focusing for incident linear polarization(LP)THz wave in three polarization conversion states,in-cluding LP without conversion,LCP and RCP.Moreover,the polarization conversion behavior is reversible,that is,the THz metalens can convert not only the LP into arbitrary single-handed CP,but also the LCP and RCP into two perpen-dicular LP,respectively.The metalens is expected to be used in advanced THz camera,as a great candidate for tradi-tional CPL and focusing lens group,and also shows potential application in polarization imaging with discriminating LCP and RCP.
文摘本文提出了一种"金属栅-开口环/硅环-金属栅"结构的透射式超表面偏振控制器,研究了入射角度和抽运光对该器件传输及偏振态控制性能的影响.研究结果表明,当线偏振太赫兹波垂直入射时,可对0.39—1.11 THz频段的太赫兹波实现偏振方向90?旋转,偏振旋转效率为99%,损耗为1 d B.对于斜入射的情况,偏振转换性能在0—60?范围内基本保持不变,且透过率达到90%以上.同时,通过调控抽运光强度的方式,该器件能够实现对透射与反射太赫兹光束的强度调制,调制深度均达到90%,且可以实现太赫兹波偏振分束功能.该器件可以作为未来太赫兹空间光通信和信息处理的宽带、角度不敏感、可调谐的偏振转换器和分束器.
文摘基于漫反射和随机编码理论提出一种应用于雷达散射截面积(RCS)缩减的超表面,并通过仿真和实验进行验证。首先,简要阐述了漫反射和随机编码理论,并设计一种基于金属分割线结构的线极化转换超单元。该结构基于"0"、"1"两种基本单元进行编码,在宽频段范围内实现180°反射相位差。仿真结果表明,超表面在6~14GHz频段内,线极化转换率高达90%,RCS缩减大于10 d B的带宽达到6 GHz。然后,设计三种随机编码超表面,进行制备和实验测试。实验结果表明:在5.5~13 GHz频带范围内,三种随机超表面在垂直入射时的反射率小于–10d B,存在6 GHz带宽RCS缩减大于10 d B,与仿真结果基本一致。另外,斜入射情况下,同样能得到有效的RCS缩减,随机编码超表面具备宽角度入射RCS缩减特性。该设计为雷达隐身技术提供了一种新的途径。
