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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Metagratings for Efficient Wavefront Manipulation
摘要： Metagratings are two-dimensional periodic arrays of individual scatterers that enable highly-efficient extreme wave transformation which was impossible using conventional metasurfaces. We review our recent progress in this area and, notably, discuss metagrating designs based on asymmetric electric dipoles that are practically easier to realize compared to bianisotropic inclusions. In addition, we present the design of a tunable metagrating based on graphene strips. It will be shown that the proposed structure can provide multiple functionalities by tuning just two bias voltages. The efficiency of the proposed design is only limited by dissipation in graphene.
关键词： wavefront manipulation,Metagratings,graphene strips,asymmetric electric dipoles,tunable metagrating
更新于2025-09-23 15:21:01
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Broadband high-efficiency cross-polarization conversion and multi-functional wavefront manipulation based on chiral structure metasurface for terahertz wave
摘要： In this paper, a broadband and high-efficient tri-layered chiral structure metasurface (CSM) for linear polarization conversion and multi-functional wavefront manipulation was proposed and investigated numerically in terahertz region. The unit-cell of the proposed CSM consist of two orthogonal metal wires sandwiched with square split-ring resonator (SRR) structure, which can manipulate the polarization and wavefront of the transmitted wave simultaneously. Based on the Fabry-Perot-like cavity-enhanced effect of proposed CSM, broadband and high-efficiency cross-polarization conversion can be achieved. Numerical simulation results indicate that the cross-polarization transmission coefficient is higher than 0.9 from 0.4 THz to 1.0 THz, with a fractional bandwidth of 85.7%. The proposed CSM can achieve complete 2π phase coverage by adjusting the geometric parameters of the unit-cell structure. As a proof of multi-functional wavefront manipulation, anomalous refraction with a wide angle, two kinds of focusing metalenses and vortex beam generation are investigated to verify the multi-functional wavefront manipulation performance of the proposed CSM. Our work provides an effective method of enhancing the performance of transmission-type metasurface and the proposed devices show endless potential in wavefront control and communication applications in terahertz region.
关键词： chiral structure metasurface,linear polarization conversion,terahertz,wavefront manipulation
更新于2025-09-23 15:19:57
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Metasurfaces for independent manipulation of the wavefronts in the different states of phase change materials
摘要： Metasurfaces have attracted increasing attention due to their extraordinary capability in the arbitrary control of electromagnetic waves. However, most metasurfaces lack flexibility and only enable fixed optical performance once fabricated. In this work, we propose ultra-thin metasurfaces with varied functionalities using phase change materials (PCMs) when phase change occurs on whole structured PCMs, which has not been found in previous reports. The wavefronts in the amorphous and crystalline states of the PCMs can be arbitrarily and independently modulated with high efficiency (～60% and ～40% in the two states, respectively). This work may be valuable for information encryption and optical communications.
关键词： wavefront manipulation,metasurfaces,information encryption,phase change materials,optical communications
更新于2025-09-09 09:28:46