共查询到17条相似文献，搜索用时 46 毫秒
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针对圆极化波, 通过同极化反射超表面结构单元的空间排布, 设计实现了一种二维非色散高效相位梯度超表面. 同极化反射相位可以通过同极化反射超表面结构单元金属线的面内旋转来自由调控. 实现的相位梯度超表面可对左右旋入射波产生相反的相位梯度. 当线极化波入射到超表面上时, 反射波被分为两束向相反方向传播的圆极化波. 仿真了线极化波垂直入射时的反射功率密度谱, 仿真结果与理论上设计的异常反射方向一致. 制作了厚度为2 mm的超表面样品, 测试了其镜面反射率曲线. 实验结果表明, 线极化波垂直入射时, 超表面在9.5-19.0 GHz的镜面反射率降至-5 dB以下. 相似文献
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偏振不敏感超表面在实际应用中具有重要意义, 本文提出了一种光通信波段的、对偏振不敏感的异常反射式梯度超表面, 这种超表面对于x-偏振和y-偏振入射光都能够实现高效率的异常反射, 表现出偏振不敏感特性, 为解决传统反射式超表面的偏振敏感性问题提供了一种新途径. 它采用金属(Au)-绝缘层(SiO2)-金属(Au)结构, 超表面的超晶胞由五个各向同性的、尺寸不同的十字形基本结构单元组成. 仿真结果表明, 这种超表面结构对不同线偏振入射平面光波有几乎相同的相位和振幅响应; 合理的选取五个基本结构单元的尺寸, 在一个超晶胞内实现了2πup 相位的覆盖, 反射光波阵面畸变小, 而且反射光都集中到异常反射级次, 在工作波长1480 nm处具有较高的异常反射率(～ 70%). 此外, 这种结构的超表面在-30°–0°的宽入射角度范围内都具有偏振不敏感的异常反射特性. 在光通信、光信号处理、显示成像等领域具有潜在的应用前景. 相似文献
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本文通过设计出一种反射型极化旋转超表面,在8—12 GHz频域内实现高效的极化旋转,并将其加载于微带缝隙天线下方构成新型的极化旋转超表面天线,利用超表面的90°极化旋转效应,成功实现了天线的圆极化辐射调制.仿真与实验结果表明:圆极化天线的中心工作频率为GHz,阻抗带宽为8.3—10 GHz.当微带缝隙天线与极化旋转超表面的间距H=4.5mm时,天线在8.3—8.8 GHz频带内实现了圆极化辐射;当mm时,天线在8.8—9.3 GHz频带内实现了圆极化辐射;当=8mm时,天线在9.3—10 GHz频带内实现了圆极化辐射.实验结果与仿真结果相符,证明了此种设计方法的有效性,也为微带缝隙天线的圆极化设计提供了一种新的途径. 相似文献
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圆极化波反射聚焦超表面 总被引：1，自引：0，他引：1
基于圆极化波入射条件下的高效同极化反射超表面实现了对圆极化反射波相位的自由调控, 设计了一维圆极化波反射聚焦超表面. 在中心频率f=16 GHz附近, 右旋圆极化平面波入射时, 反射波聚焦于焦距L=200 mm的实焦点; 左旋圆极化波入射时, 反射波近似聚焦于焦距L=-200 mm的虚焦点. 仿真计算得到聚焦波束的波束宽度、焦深. 结果表明, 这种圆极化反射聚焦超表面具有很好的聚焦效果, 同时具有长焦深和宽带特性. 相似文献
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针对相位梯度超表面在隐身技术中的应用,提出通过表面波耦合和异常反射两种机制复合实现宽频带后向雷达散射截面(RCS)缩减,采用开口谐振环进行相位梯度设计,实现了一种二维极化无关相位梯度超表面,在10 GHz附近,超表面通过将垂直入射电磁波耦合为表面波实现RCS缩减,而在大于11 GHz的频率范围内,相位分布的不均匀性使垂直入射的电磁波发生漫反射或者异常反射,降低后向RCS,制作了厚度为2 mm的超表面样品,测试了其反射率曲线和后向RCS,并与相同尺寸的金属板进行了对比,实验结果表明,在宽频段内(9.5—17.0 GHz),超表面在垂直入射情况下可将后向RCS缩减至少10 dB,由于厚度薄、重量轻、频带宽,RCS缩减超表面在隐身新材料和新技术方面具有很大的应用潜力。 相似文献
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本文设计了一种编码相位梯度超表面,用于实现太赫兹频段的雷达散射截面（RCS）缩减。依据Pancharatnam-Berry(PB)几何相位原理在超表面单元中引入相位梯度,设计出1 bit编码的两个元素“0”和“1”,使得两者的反射相位差接近180°。通过遗传算法得到编码相位梯度超表面中编码元素的最佳排列,实现了太赫兹波宽带RCS缩减。对编码相位梯度超表面进行建模分析,结果表明,在0.87～1.725 THz的宽频段内,设计的1 bit编码相位梯度超表面能实现大于10 dB的RCS缩减,最大缩减值达到31.26 dB。此外,分析了x和y极化波的入射角度变化对编码相位梯度超表面性能的影响,在0°～30°范围内,其性能稳定。以上结果表明,该类超表面在雷达隐身等方面具有潜在的应用价值。 相似文献
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将超材料设计思想与微电机系统（micro-electro-mechanical system,MEMS）技术相结合,提出了一种宽带可重构反射型极化旋转表面.该结构由上层方形金属贴片、中间介质层、金属底板以及连接贴片与底板的金属通孔构成,通过在电流短路点处加载MEMS开关,使其具有电可调特性.仿真结果表明,当MEMS开关导通时,该结构能在7.78 GHz–14.10 GHz频带内将入射的线极化波转化为正交极化波并反射;当MEMS开关断开时,入射波则以同极化全反射.加工了实际的样品并进行了测试,结果与仿真符合较好.该结构具有结构简单易加工、器件个数少、工作频带宽、损耗低等优点,在电磁波动态调控中具有潜在应用价值. 相似文献
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电磁波的极化态在信号传输和灵敏度测量中有非常重要的应用价值. 本文设计、仿真并实验验证了微波频段基于开口椭圆环谐振器的极化旋转超表面. 理论上, 将多阶表面等离子谐振和高阻抗表面相结合, 解释了多谐振点、高效率极化旋转的物理机理. 数值上, 通过对结构参数的仿真分析, 给出了运用开口椭圆环结构设计多频段、超宽带高效极化旋转超表面的方法. 所设计和制作的超表面能够在相对带宽104.5%的频率范围内实现大于85%的极化旋转效率. 这些工作将为极化操控超表面的设计和应用提供重要帮助. 相似文献
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孙文俊;汪静丽;尹亮;万洪丹;陈鹤鸣;钟凯 《光学学报》2024,(16):319-328
设计了一种2-bit编码相位梯度超表面,用于实现多波束多模态太赫兹涡旋波。根据Pancharatnam-Berry(PB)几何相位原理在超表面单元中引入相位梯度,设计出编码元素“00”“01”“10”“11”。将上述编码元素按照不同的编码序列进行排布,分别获得模态为l=-1、l=-2涡旋波的编码相位梯度超表面以及两分束的编码相位梯度超表面。利用傅里叶卷积定理,将产生涡旋波的编码序列与两分束的编码序列进行卷积,产生了l=-1或l=-2同一模态的两分束涡旋波。利用相位叠加原理,将产生不同模态的两分束涡旋波的相位相结合,构成具有新相位分布的编码相位梯度超表面。仿真结果表明：线极化波激励下,所设计的编码相位梯度超表面能同时产生两束l=-1、两束l=-2、两束l=+1和两束l=+2的涡旋波,其将在无线通信及高分辨率成像等方面有潜在的应用价值。 相似文献
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Shang Sun Zhenxing Zhou Chen Zhang Wenhong Yang Qinghai Song Shumin Xiao 《Annalen der Physik》2018,530(3)
Wide‐bandgap material based all‐dielectric metasurfaces have been ideal platforms for the realization of arbitrary phase control in visible spectrum. While TiO2 metasurfaces are very promising in broadband and high‐efficiency anomalous transmission, meta‐hologram, and meta‐lenses et al., the current realizations are strongly dependent on the sophisticated fabrication technique to fabricate TiO2 nano‐pillars with aspect ratio > 10. Herein we experimentally demonstrate a much simpler approach to realize efficient phase control of visible light. By exploiting TiO2 nano‐blocks as meta‐atoms on a ground metal plane, we find that TiO2 metasurface with aspect ratio around 1‐1.5 is good enough to produce phase changes covering ‐π to π and high reflection efficiency simultaneously. Based on the phase control of the meta‐reflectarray, anomalous reflection with a ratio between anomalous reflection and normal reflection ～ 74/26 have been experimentally realized using a combination of typical electron‐beam lithography, electron‐beam evaporation, and a simple lift‐off process. Similarly, high performance TiO2 metasurface in form of hologram has also been demonstrated for red (633 nm), green (520 nm), and blue (445 nm) wavelengths. We believe this research shall route a new way to cost‐effective all‐dielectric metasurfaces and advance their applications in encryption, anti‐counterfeiting, and wearable displays. 相似文献
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A new method to design an ultra-thin high-gain circularly-polarized antenna system with high efficiency is proposed based on the geometrical phase gradient metasurface(GPGM).With an accuracy control of the transmission phase and also the high transmission amplitude,the GPGM is capable of manipulating an electromagnetic wave arbitrarily.A focusing transmission lens working at Ku band is well optimized with the F /D of 0.32.A good focusing effect is demonstrated clearly by theoretical calculation and electromagnetic simulation.For further application,an ultra-thin single-layer transmissive lens antenna based on the proposed focusing metasurface operating at 13 GHz is implemented and launched by an original patch antenna from the perspective of high integration,simple structure,and low cost.Numerical and experimental results coincide well,indicating the advantages of the antenna system,such as a high gain of 17.6 d B,the axis ratio better than 2 d B,a high aperture efficiency of 41%,and also a simple fabrication process based on the convenient print circuit board technology.The good performance of the proposed antenna indicates promising applications in portable communication systems. 相似文献
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Polarization conversion is a very important electromagnetic wave manipulation method. In this paper, we investigate a high-efficiency linear-to-circular polarization and cross-polarization converter by utilizing coding metasurface. The coding particle consists of top layer metal pattern and bottom metal plate sandwiched with square F4B dielectric, which can manipulate the linear-to-circular polarization and cross-polarization converter of the reflected wave simultaneously. In the terahertz frequency range of 1.0 THz-2.0 THz, the reflection magnitudes reach approximately 90% and the axial ratio is less than 3 dB. The proposed polarization converter may lead to advances in a variety of applications such as security, microscopy, information processing, stealth technology, and data storage. 相似文献
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《Laser u0026amp; Photonics Reviews》2017,11(6)
Metasurfaces, the phase‐engineered quasi‐2D interfaces, have attracted intensive interest due to their great capabilities in manipulating the reflection, refraction and transmission of electromagnetic waves. Here, we demonstrate the design and realization of a gradient chiral metamirror tailored for spin‐selective anomalous reflection based on the theory of Pancharatnam‐Berry phase. Asymmetric split ring resonators are employed as the basic meta‐atoms for strong circular dichroism. Dispersionless phase discontinuities are achieved by adjusting the orientation of the meta‐atoms, and spin‐dependent absorption is realized by introducing a chiral resonance. Theoretical results predict both broadband beam deflection and spin‐selective absorption for circularly polarized waves in a designer metamirror. Experimental verification of this bifunctional performance is implemented at microwave frequencies and the measured results agree well with the simulation ones. Such chiral metamirrors could pave an avenue towards spin‐selective modulation of the wavefront and might find promising applications in planar electromagnetic devices. 相似文献
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Chen Hong-Ya Wang Jia-Fu Ma Hua Qu Shao-Bo Zhang Jie-Qiu Xu Zhuo Zhang An-Xue 《中国物理 B》2015,24(1):14201-014201
We propose a broadband perfect polarization conversion metasurface composed of copper sheet-backed asymmetric double spilt ring resonator(DSRR).The broadband perfect polarization convertibility results from metallic ground and multiple plasmon resonances of the DSRR.Physics of plasmon resonances are governed by the electric and magnetic resonances.Both the simulation and measured results show that the polarization conversion ratio(PCR)is higher than 99%for both x-and y-polarized normally incident EM waves and the fractional bandwidth is about 34.5%.The metasurface possesses the merits of high PCR and broad bandwidth,and thus has great application values in novel polarization-control devices. 相似文献
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The terahertz technology has attracted considerable attention because of its potential applications in various fields.However,the research of functional devices,including polarization converters,remains a major demand for practical applications.In this work,a reflective dual-functional terahertz metadevice is presented,which combines two different polarization conversions through using a switchable metasurface.Different functions can be achieved because of the insulator-to-metal transition of vanadium dioxide(VO2).At room temperature,the metadevice can be regarded as a linear-to-linear polarization convertor containing a gold circular split-ring resonator(CSRR),first polyimide(PI)spacer,continuous VO2 film,second PI spacer,and gold substrate.The converter possesses a polarization conversion ratio higher than 0.9 and a bandwidth ratio of 81%in a range from 0.912 THz to 2.146 THz.When the temperature is above the insulator-to-metal transition temperature(approximately 68℃)and VO2 becomes a metal,the metasurface transforms into a wideband linear-to-circular polarization converter composed of the gold CSRR,first PI layer,and continuous VO2 film.The ellipticity is close to-1,while the axis ratio is lower than 3 dB in a range of 1.07 THz-1.67 THz.The metadevice also achieves a large angle tolerance and large manufacturing tolerance. 相似文献
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The terahertz (THz) resonance, chirality, and polarization conversion properties of a double-layer chiral metasurface have been experimentally investigated by THz time domain spectroscopy system and polarization detection method. The special symmetric geometry of each unit cell with its adjacent cells makes a strong chiral electromagnetic response in this metasurface, which leads to a strong polarization conversion effect. Moreover, compared with the traditional THz transmission resonance sensing for film thickness, the polarization sensing characterized by polarization elliptical angle (PEA) and polarization rotation angle (PRA) shows a better Q factor and figure of merit (FoM). The results show that the Q factors of the PEA and PRA reach 43.8 and 49.1 when the interval film is 20 μm, while the Q factor of THz resonance sensing is only 10.6. And these PEA and PRA can play a complementary role to obtain a double-parameter sensing method with a higher FoM, over 4 times than that of resonance sensing. This chiral metasurface and its polarization sensing method provide new ideas for the development of high-efficiency THz polarization manipulation, and open a window to the high sensitive sensing by using THz polarization spectroscopy. 相似文献