Resonant responses of metasurface enable effective control over the polarization properties of lights. In this paper,we demonstrate a double-rod metasurface for broadband polarization conversion in the mid-infrared re...Resonant responses of metasurface enable effective control over the polarization properties of lights. In this paper,we demonstrate a double-rod metasurface for broadband polarization conversion in the mid-infrared region. The metasurface consists of a metallic double-rod array separated from a reflecting ground plane by a film of zinc selenide. By superimposing three localized resonances, cross polarization conversion is achieved over a bandwidth of 16.9 THz around the central frequency at 34.6 THz with conversion efficiency exceeding 70%. The polarization conversion performance is in qualitative agreement with simulation. The surface current distributions and electric field profiles of the resonant modes are discussed to analyze the underlying physical mechanism. Our demonstrated broadband polarization conversion has potential applications in the area of mid-infrared spectroscopy, communication, and sensing.展开更多
Simultaneous broadband absorption and polarization conversion are crucial in many practical applications,especially in terahertz communications.Thus,actively tunable metamaterial systems can exploit the graphene-based...Simultaneous broadband absorption and polarization conversion are crucial in many practical applications,especially in terahertz communications.Thus,actively tunable metamaterial systems can exploit the graphene-based nanomaterials derived from renewable resources because of the flexible surface conductivity and selective permeability of the nanomaterials at terahertz frequencies.In this paper,we propose a graphene-based active tunable bifunctional metasurface for dynamic terahertz absorption and polarization conversion.The graphene ring presents a certain opening angle(A)along the diagonal of the xoy plane.When A=0°,the proposed metasurface behaves as a broadband absorber.Numerical results show the feasibility of achieving this polarization-insensitive absorber with nearly 100%absorptance,and the bandwidth of its 90%absorptance is 1.22 THz under normal incidence.Alternatively,when A=40°after optimization,the proposed metasurface serves as a broadband polarization convertor,resulting in robust broadband polarization conversion ratio(PCR)curves with a bandwidth surpassing 0.5 THz in the reflection spectrum.To tune the PCR response or the broad absorption spectrum of graphene,we change the Fermi energy of graphene dynamically from 0 to 0.9 eV.Furthermore,both the broadband absorption and the linear polarization conversion spectra of the proposed metasurface exhibit insensitivity to the incident angle,allowing large incident angles within 40°under high-performance operating conditions.To demonstrate the physical process,we present the impedance matching theory and measure electric field distributions.This architecture in the THz frequency range has several applications,such as in modulators,sensors,stealth,and optoelectronic switches.THz wave polarization and beam steering also have broad application prospects in the field of intelligent systems.展开更多
We proposed a sandwich structure to realize broadband asymmetric transmission(AT) for both linearly and circularly polarized waves in the near infrared spectral region. The structure composes of a silica substrate and...We proposed a sandwich structure to realize broadband asymmetric transmission(AT) for both linearly and circularly polarized waves in the near infrared spectral region. The structure composes of a silica substrate and two sand-clock-like gold layers on the opposite sides of the substrate. Due to the surface plasmons of gold, the structure shows that the AT parameters of linearly and circularly polarized waves can reach 0.436 and 0.403, respectively. Meanwhile, a broadband property is presented for the AT parameter is over 0.3 between 320 THz and 340 THz. The structure realizes a diode-like AT for linearly wave in forward and circularly wave in backward, respectively. The magnetic dipoles excited by current in the two gold layers contribute to the broadband AT. The current density in top and bottom metallic layers illustrates the mechanism of the polarization conversion for broadband AT in detail.展开更多
基于线-圆极化转换原理和聚焦超表面相关理论,设计了一种反射型宽带线-圆极化转换聚焦超表面,并结合线极化馈源设计了宽带的高增益圆极化天线.首先,提出了一种单层的变形十字超表面单元,单元具有极化独立特性,并且能够在10—14 GHz宽频...基于线-圆极化转换原理和聚焦超表面相关理论,设计了一种反射型宽带线-圆极化转换聚焦超表面,并结合线极化馈源设计了宽带的高增益圆极化天线.首先,提出了一种单层的变形十字超表面单元,单元具有极化独立特性,并且能够在10—14 GHz宽频带范围实现对反射波相位360?范围全调控,同时利用该单元构建的一维超单元很好地验证了奇异反射现象.然后,分别控制单元横向和纵向尺寸的分布构建出同时满足线-圆极化转换和聚焦条件的双功能超表面.最后,采用Vivaldi天线作为馈源对超表面进行照射组成天线系统,仿真及测试结果均表明天线系统同时实现了高增益和线-圆极化转换,系统的-1 d B带宽为24%,-3 d B轴比带宽为29.8%.本文的设计充分体现了超表面对电磁波相位和极化操控的灵活性,具有显著的应用前景.展开更多
基金Project supported by the National Natural Science Foundation of China(Grants Nos.61421002 and 61575036)the Chinese National 1000 Plan for Young Talentsthe Startup Funding from University of Electronic Science and Technology of China
文摘Resonant responses of metasurface enable effective control over the polarization properties of lights. In this paper,we demonstrate a double-rod metasurface for broadband polarization conversion in the mid-infrared region. The metasurface consists of a metallic double-rod array separated from a reflecting ground plane by a film of zinc selenide. By superimposing three localized resonances, cross polarization conversion is achieved over a bandwidth of 16.9 THz around the central frequency at 34.6 THz with conversion efficiency exceeding 70%. The polarization conversion performance is in qualitative agreement with simulation. The surface current distributions and electric field profiles of the resonant modes are discussed to analyze the underlying physical mechanism. Our demonstrated broadband polarization conversion has potential applications in the area of mid-infrared spectroscopy, communication, and sensing.
基金supported by the High Level Talent Project of Basic and Applied Basic Research(Natural Science)of Hainan Province in 2019(No.2019RC158)by the Project of the Education Department of Hainan Province(No.Hnky2020ZD-2),all support is gratefully acknowledged.
文摘Simultaneous broadband absorption and polarization conversion are crucial in many practical applications,especially in terahertz communications.Thus,actively tunable metamaterial systems can exploit the graphene-based nanomaterials derived from renewable resources because of the flexible surface conductivity and selective permeability of the nanomaterials at terahertz frequencies.In this paper,we propose a graphene-based active tunable bifunctional metasurface for dynamic terahertz absorption and polarization conversion.The graphene ring presents a certain opening angle(A)along the diagonal of the xoy plane.When A=0°,the proposed metasurface behaves as a broadband absorber.Numerical results show the feasibility of achieving this polarization-insensitive absorber with nearly 100%absorptance,and the bandwidth of its 90%absorptance is 1.22 THz under normal incidence.Alternatively,when A=40°after optimization,the proposed metasurface serves as a broadband polarization convertor,resulting in robust broadband polarization conversion ratio(PCR)curves with a bandwidth surpassing 0.5 THz in the reflection spectrum.To tune the PCR response or the broad absorption spectrum of graphene,we change the Fermi energy of graphene dynamically from 0 to 0.9 eV.Furthermore,both the broadband absorption and the linear polarization conversion spectra of the proposed metasurface exhibit insensitivity to the incident angle,allowing large incident angles within 40°under high-performance operating conditions.To demonstrate the physical process,we present the impedance matching theory and measure electric field distributions.This architecture in the THz frequency range has several applications,such as in modulators,sensors,stealth,and optoelectronic switches.THz wave polarization and beam steering also have broad application prospects in the field of intelligent systems.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11965009,61874036,61805053,and 61764001)the Natural Science Foundation of Guangxi Zhuang Autonomous Region,China(Grant Nos.2018JJA170010 and 2018GXNSFAA281193)the Innovation Project of GUET Graduate Education(Grant No.2020YCXS019)。
文摘We proposed a sandwich structure to realize broadband asymmetric transmission(AT) for both linearly and circularly polarized waves in the near infrared spectral region. The structure composes of a silica substrate and two sand-clock-like gold layers on the opposite sides of the substrate. Due to the surface plasmons of gold, the structure shows that the AT parameters of linearly and circularly polarized waves can reach 0.436 and 0.403, respectively. Meanwhile, a broadband property is presented for the AT parameter is over 0.3 between 320 THz and 340 THz. The structure realizes a diode-like AT for linearly wave in forward and circularly wave in backward, respectively. The magnetic dipoles excited by current in the two gold layers contribute to the broadband AT. The current density in top and bottom metallic layers illustrates the mechanism of the polarization conversion for broadband AT in detail.
文摘基于线-圆极化转换原理和聚焦超表面相关理论,设计了一种反射型宽带线-圆极化转换聚焦超表面,并结合线极化馈源设计了宽带的高增益圆极化天线.首先,提出了一种单层的变形十字超表面单元,单元具有极化独立特性,并且能够在10—14 GHz宽频带范围实现对反射波相位360?范围全调控,同时利用该单元构建的一维超单元很好地验证了奇异反射现象.然后,分别控制单元横向和纵向尺寸的分布构建出同时满足线-圆极化转换和聚焦条件的双功能超表面.最后,采用Vivaldi天线作为馈源对超表面进行照射组成天线系统,仿真及测试结果均表明天线系统同时实现了高增益和线-圆极化转换,系统的-1 d B带宽为24%,-3 d B轴比带宽为29.8%.本文的设计充分体现了超表面对电磁波相位和极化操控的灵活性,具有显著的应用前景.
