A broadband terahertz quarter wave plate based on asymmetric cross slots

In this paper, a transmissive terahertz (THz) quarter wave plate (QWP) has been proposed to realize the linear-to-circular polarization conversion in terahertz range. This quarter wave plate is composed of two dielectric layers and one metallic layer with asymmetric cross slots. In the range of 0.894—1.378 THz, the axis ratio of proposed device is less than 3 dB, and its polarization conversion efficiency is more than 45%. The distributions of surface currents and electromagnetic field density had been proposed to understand the physical mechanism of proposed device. The linear-to-circular polarization conversion can be attributed to the asymmetric transmission along slots. Finally, the simulation results are validated by experiments in terahertz region. The proposed device has simple geometry and good performance, which can be used as a key component in applications of terahertz communications, terahertz imaging and terahertz sensing.     

Design of multi-channel terahertz beam splitter based on Z-shaped metasurface

A reflective beam splitter is proposed and verified. The unit cell of the beam splitter is composed of a metal pattern, a dielectric substrate, and a metallic ground. Each subarray structure of the device is composed of four unit cells, which are gradually rotated at 45°. The horizontal and vertical subarrays form a 4×4 gradient metasurface supercell. In the operating frequency band, the incident linearly polarized terahertz wave is reflected and divided into four beams of approximately equal power but different propagation directions. The proposed terahertz beam splitter based on metasurface has the advantages of small size, low cost and easy processing, and can be applied to terahertz stealth and imaging.     

太赫兹超材料分束器设计及其特性分析

提出一种超材料太赫兹分束器,其单元结构由顶层金属条带、中间介质层和底层金属板组成。利用4个旋转步进为45°的单元周期排列构成了4×4的相位梯度超表面。当太赫兹波垂直入射到阵列表面时,电磁波被反射成四束能量相等但传播方向不同的波,且不同频点的反射角不同。该分束器具有体积小、成本低的优点,可应用于太赫兹隐身和太赫兹成像等方面。     

太赫兹宽带非对称传输器件的研究

提出一款双层双L形太赫兹非对称传输器件,其结构单元由典型的金属-介质-金属结构组成,顶层为轴对称的双L形金属层,底层为中心对称的双L形金属层。在1.174~1.420THz范围内,当x极化波正向垂直入射时,该器件的非对称传输参数大于0.6,其中在1.207~1.377THz范围内非对称传输参数大于0.8,在1.334THz时非对称传输参数达到峰值0.859。最后,讨论了材料的选择和入射角度对器件非对称传输性能的影响。该非对称传输器件具有频带宽、非对称传输明显等特点,可用于太赫兹二极管、太赫兹开关等功能器件。     

基于超材料的太赫兹1/4波片设计及特性分析

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。