借助于结构化的金属/介质界面所形成的人工表面等离激元，能够将太赫兹场束缚在亚波长量级，同时利用单元结构对几何参数的色散特性，可以在二维尺度上操纵太赫兹波，为集成化、小型化片上太赫兹功能器件的发展提供了解决途径。利用立体金属柱子结构的色散特性构建二维渐变折射率透镜，在此基础之上设计平面望远镜、波导耦合器、双功能透镜等二维太赫兹人工表面等离激元传输调控器件，并通过电磁仿真分析每种功能器件的工作性能。本工作不仅丰富了太赫兹表面波调控器件家族，并有望进一步发展表面等离激元链路的太赫兹片上系统。

提出了一种基于人工表面等离激元（SSPPs）的太赫兹低损耗传输线，并通过加载开口谐振环（SRR）实现了具有大抑制深度的太赫兹带阻滤波器。采用不规则阶梯渐变过渡结构对SSPPs传输线进行了优化，降低了其在太赫兹频段下的传输损耗及不平坦度。通过色散分析揭示了加载SRR和不加载SRR的SSPPs传输线的频段抑制机理。加载SRR的SSPPs传输线工作在基模和一阶高次模两种模式下，其基模具有低通特性，一阶高次模具有带通特性，实现了具有通带-阻带-通带-阻带的太赫兹滤波特性。通过调节SRR的几何参数，可控制SSPPs滤波器的阻带频率；通过增加SRR的加载数量，可增大SSPPs滤波器的抑制深度。为了验证设计的可行性，采用微纳加工技术分别制作了所提出的SSPPs传输线和滤波器，并进行了太赫兹在片测试。测试结果表明：在0.11~0.17 THz频带范围内，SSPPs传输线的插入损耗小于0.5 dB/mm，回波损耗优于10 dB；SSPPs滤波器在0.142~0.156 THz频率范围内的抑制深度大于10 dB，最大抑制深度为45 dB@0.148 THz；实验结果与仿真结果具有良好的吻合度。该研究对太赫兹等离激元集成系统研究具有重要意义。

基于人工表面等离子体激元（SSPPs）的一阶高次模，设计了一种具有优异带通性能的滤波器。所采用的SSPPs单元结构为类八木天线结构，该结构可以有效降低SSPPs的渐近频率。此外，通过改变SSPPs单元结构的几何参数，可独立控制其渐近频率和与自由空间中光线的交点频率。与具有低通特性的SSPPs基模相比，一阶高次模具有天然的带通特性，且不需要采用额外的阶梯渐变过渡结构。为了验证SSPPs高阶模式应用于带通滤波器设计的可行性，制作并测量了基于该方法的SSPPs滤波器。测试结果表明，该滤波器在6~9.9 GHz的通带频率范围内的插入损耗小于1 dB，带内回波损耗优于10 dB，实验结果与仿真结果具有良好的吻合度。

Controlling energy flow in waveguides has attractive potential in integrated devices from radio frequencies to optical bands. Due to the spin-orbit coupling, the mirror symmetry will be broken, and the handedness of the near-field source will determine the direction of energy transport. Compared with well-established theories about spin-momentum locking, experimental visualization of unidirectional coupling is usually challenging due to the lack of generic chiral sources and the strict environmental requirement. In this work, we design a broadband near-field chiral source in the microwave band and discuss experimental details to visualize spin-momentum locking in three different metamaterial waveguides, including spoof surface plasmon polaritons, line waves, and valley topological insulators. The similarity of these edge waves relies on the abrupt sign change of intrinsic characteristics of two media across the interface. In addition to the development of experimental technology, the advantages and research status of interface waveguides are summarized, and perspectives on future research are presented to explore an avenue for designing controllable spin-sorting devices in the microwave band.

Glide symmetry, which is one kind of higher symmetry, is introduced in a special type of plasmonic metamaterial, the transmission lines (TLs) of spoof surface plasmon polaritons (SSPPs), in order to control the dispersion characteristics and modal fields of the SSPPs. We show that the glide-symmetric TL presents merged pass bands and mode degeneracy, which lead to broad working bandwidth and extremely low coupling between neighboring TLs. Dual-conductor SSPP TLs with and without glide symmetry are arranged in parallel as two channels with very deep subwavelength separation (e.g., λ₀ / 100 at 5 GHz) for the application of integrated circuits and systems. Mutual coupling between the hybrid channels is analyzed using coupled mode theory and characterized in terms of scattering parameters and near-field distributions. We demonstrate theoretically and experimentally that the hybrid TL array obtains significantly more suppressed crosstalk than the uniform array of two nonglide symmetric TLs. Hence, it is concluded that the glide symmetry can be adopted to flexibly design the propagation of SSPPs and benefit the development of highly compact plasmonic circuits.

以微带为代表的传统微波传输线无法精细操控电磁模式,因此传统电子信息系统在空间耦合、动态响应和性能鲁棒性等方面存在瓶颈。人工表面等离激元(SSPP)超材料可打破上述瓶颈,是光学与信息领域的研究热点之一。人工表面等离激元超材料是一类模拟光频段表面等离激元特性的新型超材料,可在微波和太赫兹频段精细操控表面波,具有与平面电路相似的构型特性,可用于制备下一代集成电路的基础传输线。人工表面等离激元分为传输型和局域型两类。传输型人工表面等离激元超材料始于三维立体结构,后发展成超薄梳状金属条带构型。学者们构建了以其为基础的微波电路新体系,研制了人工表面等离激元滤波器、天线、放大器和倍频器等典型的无源和有源器件,并将其集成为可实现亚波长间距多通道信号非视距传输的无线通信系统。人工局域表面等离激元(SLSP)超材料也经历了从三维立体构型到超薄构型的发展历程,并通过螺旋构型、链式构型、高阶模式和杂化模式等为电磁波的亚波长尺度调控提供了更多自由度。系统讨论了人工表面等离激元超材料在微波电路中的相关理论和应用,包括人工表面等离激元超材料的基本概念、构型发展、无源/有源器件以及无线通信系统。

基于人工表面等离子体激元(SSPPs)设计了具有陷波功能的多频带滤波器。首先,在波导结构上引入了渐变槽形单元结构,以获得更好的色散特性,并在此基础上构建了截止频率为7.1 GHz的低通滤波器。然后,通过加载E形谐振器激发陷波,形成多频带滤波器,该谐振器有奇偶模两种谐振模式。当奇偶谐振模式同时被激发时,构成了插入损耗为3 dB、截止频率为2.83 GHz的低通滤波器和插入损耗为3 dB,带宽为2.94~4.37 GHz和4.40~7.10 GHz的两个带通滤波器。在偶模式下的谐振退化消失时,构成了插入损耗为3 dB、截止频率为2.83 GHz的低通滤波器和插入损耗为3 dB、截止频率为2.94~7.10 GHz的带通滤波器。证明了基于E型谐振器的多频带滤波器结构对SSPPs在微波领域的拓展具有重要意义。