基于超材料的太赫兹1/4波片设计及特性分析
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摘要
提出了一种基于超材料的透射式太赫兹1/4波片,将传统的开环谐振型结构改进为"叉指"型结构,实现了线极化波向圆极化波的有效转换。测试表明,在0.818～0.973THz内,透射波的轴比小于3dB,椭圆度χ>0.81,器件将线极化波转换为圆极化波的效率为50%～75%。与现有的太赫兹1/4波片相比,该器件极化转换效率高、结构简单,仅由一层介质层和两层金属层组成。所提出的太赫兹1/4波片在太赫兹无线通信、太赫兹成像等领域具有重要的应用前景。
A transmissive terahertz quarter-wave plate based on metamaterial is proposed,which optimizes the traditional split-ring resonantor structure with an "interdigital" structure,realizing the effective conversion of linearly polarized waves into circularly polarized waves.In the wide frequency range of 0.818～0.973 THz,the axial ratio of the transmitted wave is less than 3 dB,and its ellipticityχis greater than 0.81.The conversion efficiency from linearly polarized wave to circularly polarized wave is 50%～75%.Compared with those existing terahertz quarterwave plate,this proposed device composed of only one dielectric layer and two metal layers presents high polarization conversion efficiency and simple structure,showing important application prospects in the fields of terahertz wireless communication and terahertz imaging.
A transmissive terahertz quarter-wave plate based on metamaterial is proposed,which optimizes the traditional split-ring resonantor structure with an "interdigital" structure,realizing the effective conversion of linearly polarized waves into circularly polarized waves.In the wide frequency range of 0.818～0.973 THz,the axial ratio of the transmitted wave is less than 3 dB,and its ellipticityχis greater than 0.81.The conversion efficiency from linearly polarized wave to circularly polarized wave is 50%～75%.Compared with those existing terahertz quarterwave plate,this proposed device composed of only one dielectric layer and two metal layers presents high polarization conversion efficiency and simple structure,showing important application prospects in the fields of terahertz wireless communication and terahertz imaging.
引文
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[2] Chen L,Ke X,Guo H,et al.Broadband wave plates made by plasmonic metamaterials[J].Scientific Reports,2018,8:1051.
[3] Wang D,Gu Y,Gong Y,et al.An ultrathin terahertz quarterwave plate using planar babinet-inverted metasurface[J].Opt.Express,2015,23(9):11114-11122.
[4] Nouman M T,Hwang J H,Jang J H.Ultrathin terahertz quarter-wave plate based on split ring resonator and wire grating hybrid metasurface[J].Scientific Reports,2016,6:39062.
[5] Han Z,Ohno S,Tokizane Y,et al.Off-resonance and inresonance metamaterial design for a high-transmission terahertz-wave quarter-wave plate[J].Opt.Lett.,2018,43(12):2977-2980.
[6] Li Y,Zhang J,Qu S,et al.Achieving wide-band linear-tocircular polarization conversion using ultra-thin bi-layered metasurfaces[J].J.of Appl.Phys.,2015,117(4):044501.
[7] Jiang Y, Wang L, Wang J,et al.Ultra-wideband highefficiency reflective linear-to-circular polarization converter based on metasurface at terahertz frequencies[J].Opt.Express,2017,25(22):27616-27623.
[8] Loo Y L,Guo B S,Ong C K.Substrateless ultra-thin quarter meta-waveplate based on Babinets principle[J].J.of Opt.,2018,20(6):065101.