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通过调制电磁波的相位和振幅可以达到控制电磁波的目的,为了实现超材料器件对电磁波的不同响应,利用仿真软件CST,设计了一系列基于全介质超材料的波前控制器件,包括电磁波偏转器件和聚焦透镜。通过引入不同的梯度相位差,达到调制折射电磁波偏转方向的目的,且当器件满足不同的相位分布时,透镜的焦点位置可以被定量调节。这些全介质超材料器件可通过3D打印技术快速制备,具备经济友好的特点,在微波成像系统和通信领域具有广泛的应用前景。 相似文献
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利用不同厚度的亚波长介质块实现0 ~2π的相位变化,并基于惠更斯人工电磁表面原理设计了工作
于28 GHz 通信频段的全介质电磁透镜,该电磁透镜的焦距与口径比(F / D)为0. 15。通过3D 打印制备该电磁透镜,
并将其与基片集成波导(SIW)贴片天线进行集成,构造了超低剖面的宽带透镜天线。全波分析与实验测量结果显示
该电磁透镜能够将原SIW 贴片天线的增益提高7 dB 左右,而将3 dB 波束宽度减小到10°左右,同时该透镜天线系统
还具有良好的低副瓣。 相似文献
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All-dielectric self-supporting (ADSS) cables are installed along with transmission line for the purpose of communication. During installation the outer layer of the cable is hydrophobic and is not pron... 相似文献
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Yi Xu Jianqiang Gu Yufei Gao Quanlong Yang Wanying Liu Zhibo Yao Quan Xu Jiaguang Han Weili Zhang 《Advanced functional materials》2023,33(35):2302821
Metasurfaces have proved to possess extraordinary properties and propelled the development of versatile functional devices in the terahertz domain, but the intrinsic dispersion severely impedes their broadband applications. Sporadic studies on achromatic terahertz metasurfaces are either subject to specific polarization operation or challenged in the fabrication process for extended bandwidth and numerical aperture. Herein a novel meta-atom scheme made up of a silicon–silica–silicon sandwich-shaped structure is presented that enlarges the propagation phase as well as improves the dispersion engineering capability at low losses. As a classic case, an achromatic metalens is constituted by these meta-atoms and experimentally demonstrated which shows a remarkable achromatic focusing performance from 0.5 to 1.1 THz with a numerical aperture of 0.47 and an average efficiency as high as 43.1%. Continuous wavelet transformation analysis further proves the metalens has negligible group delay dispersion. This study not only demonstrates an outstanding terahertz achromatic metalens but also provides a novel meta-atom paradigm for constructing achromatic metasurfaces such as holographic plate, beam deflector, and Bessel axicon, further not limited to THz bands. 相似文献
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超透镜凭借其独特的优势逐渐取代或补充了传统的折光和衍射透镜,从而领先小型化高性能光学设备和系统。这种小型化有望带来紧凑的纳米级光学设备,应用于相机、照明、显示器和可穿戴光学。但在传统的超透镜设计中,几何相位通常需要左右旋圆偏振光的手性限制。为了使其不再局限于左旋圆偏振光(LCP)和右旋圆偏振光(RCP)入射,设计了基于几何相位的全介质超透镜,实现了线偏振光的近场聚焦,其与超表面滤光片主要输出波长(可见光波段)一致。采用有效时域差分法研究并验证了超透镜各变量对光场聚焦特性的影响,超透镜等其他超表面光学元器件前所未有的设计自由度将极大地扩大微光学和集成光学的应用领域。 相似文献
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Juan Wang Julius Kühne Theodosios Karamanos Carsten Rockstuhl Stefan A. Maier Andreas Tittl 《Advanced functional materials》2021,31(46):2104652
Metasurfaces based on quasi-bound states in the continuum (quasi-BICs) constitute an emerging toolkit in nanophotonic sensing as they sustain high quality factor resonances and substantial near-field enhancements. It is demonstrated that silicon metasurfaces composed of crescent shaped meta-atoms provide tailored light-matter interaction controlled by the crescent geometry. Significantly, this metasurface not only exhibits a fundamental quasi-BIC resonance, but also supports a higher-order resonance with tunable electromagnetic field enhancement and advantageous properties for sensing. The higher-order resonance shows twice the sensitivity of the fundamental one for bulk refractive index sensing. It is further demonstrated that both the fundamental and higher-order resonances can be exploited for sensing ultrathin layers of biomolecules in air and buffer solutions. Specifically, when measuring in buffer solution, the figure of merit of the sensor, defined as the change in the spectral position of the resonance normalized to its full width at half maximum, is a factor of 2.5 larger for the higher-order resonance when compared to the fundamental one. Due to its high sensitivity and potential for straightforward microfluidic integration, the silicon crescent metasurface is ideally suited for real-time and in situ biosensing, enabling compact sensing devices for a wide range of diagnostic applications. 相似文献
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Jingyi Tian Giorgio Adamo Hailong Liu Mengfei Wu Maciej Klein Jie Deng Norman Soo Seng Ang Ramón Paniagua-Domínguez Hong Liu Arseniy I. Kuznetsov Cesare Soci 《Advanced materials (Deerfield Beach, Fla.)》2023,35(1):2207430
Metasurfaces supporting optical bound states in the continuum (BICs) are emerging as simple and compact optical cavities to realize polarization-vortex lasers. The winding of the polarization around the singularity defines topological charges which are generally set by the cavity design and cannot be altered without changing geometrical parameters. Here, a subwavelength-thin phase-change halide perovskite BIC metasurface functioning as a tunable polarization vortex microlaser is demonstrated. Upon the perovskite structural phase transitions, both its refractive index and gain vary substantially, inducing reversible and bistable switching between distinct polarization vortexes underpinned by opposite topological charges. Dynamic tuning and switching of the resulting vector beams may find use in microscopy imaging, particle trapping and manipulation, and optical data storage. 相似文献
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