A polarization-insensitive, square split-ring resonator（SSRR） is simulated and experimented. By investigating the influence of the asymmetrical arm width in typical SSRRs, we find that the variation of the arm width enables a blue shift of the resonance frequency for the 0° polarized wave and a red shift of the resonance frequency for the 90° polarized wave. Thus, the resonance frequency for the 0° polarized wave and the resonance frequency for the 90° polarized wave will be identical by asymmetrically adjusting the arm width of the SSRR. Two modified, split-ring resonators（MSRRs） that are insensitive to the polarization with asymmetrical arm widths are designed, fabricated, and tested. Excellent agreement between the simulations and experiments for the MSRRs demonstrates the polarization insensitivity with asymmetrical arm widths. This work opens new opportunities for the investigation of polarization-insensitive, split-ring resonator metamaterials and will broaden the applications of split-ring resonators in various terahertz devices.
Surface plasmon polaritons excited by an electron beam can be transformed into coherent and tunable light radiation waves with power enhancement in the simple structure of a metal film with a dielectric medium loading. In this paper, the process of the radiation transformation of this radiation, and the dependencies of the radiation characteristics on the parameters of the structure and the electron beam are studied in detail. The radiation power enhancement is greatly influenced by the beam energy and the film thickness in the infrared to ultraviolet frequency region. Up to 122 times radiation power enhancement and 6.5% radiation frequency tuning band can be obtained by optimizing the beam energy and the parameters of the film.
本文提出一种基于圆台形吸收单元的超宽带、极化不敏感的超材料太赫兹吸收器.该超材料吸收器采用金属薄膜金和介质层二氧化硅交替叠加的多层结构.采用商业软件CST Studio Suite 2009时域求解器计算了其在0—10 THz波段内的吸收率A(ω),在2—10 THz之间实现了对入射太赫兹波的超宽频带强吸收.仿真结果表明,由于其圆台形单元结构,在器件垂直方向上形成一系列不同尺寸的微型吸收器,产生了吸收频点相连的多频吸收峰.利用不同吸收峰的耦合叠加效应,获得超过8 THz的超宽带太赫兹波吸收,吸收强度达到92.3%以上.这一结构具有超宽带强吸收,360极化不敏感以及易于加工等优越特性,因而在太赫兹波探测器、光谱成像以及隐身技术方面具有潜在的应用.
Two-dimensional metallic photonic crystal slabs with square lattice are proposed to be used for the design of waveguide bandpass filters operating in millimeter to terahertz region. Filter characteristics are studied when rod radii and lattice constants are changed. Based on the frequency scaling technique, a series of higher frequency filters has been designed. By using laser drilling and welding processing techniques, a compact waveguide filter embedded in an EIA-WR10 waveguide with central frequency 145.5 GHz and 3-dB bandwidth of 5.26 GHz is fabricated and measured. The measurement data agree well with the simulation prediction.
