一种实现中红外非对称传输的手征超表面设计

为了研究手征超表面在中红外波段的非对称传输特性，设计了一种基于L型结构的手征超表面单元。利用CST电磁软件进行仿真分析，结果表明在68.92~88.68 THz范围内非对称传输参数大于0.8，在73.25 THz处非对称传输参数达到极值为0.88，由此可知该结构在中红外波段具有良好的非对称传输特性；通过分析表面电流分布和透射场相位分布，阐明了该手征超表面的极化选择性反射和交叉极化透射机理；对单元结构手征强弱和非对称传输特性的关系进行了讨论，并研究了介质层、金属层的厚度以及电磁波入射角度对非对称传输特性的影响。

Chiral Metasurface Designed for the AsymmetricTransmission of the Mid-infrared Band

To study the asymmetric transmission characteristics of the chiral metasurface in the mid-infrared band,a chiral metasurface unit based on an L-shaped structure isdesigned.A simulation analysis using CST electromagnetic software reveals that the asymmetric transmission parameter is greater than 0.8 in the range of 68.92-88.68 THz and reaches the extreme value of 0.88 at 73.25 THz.It can be observedthat the structure exhibits good performance in terms of asymmetric transmission in the mid-infrared band.The polarization selective reflection and cross-polarization transmission mechanism of the chiral metasurface are clarified by analyzing the surface current distribution and phase distribution of the transmission field.The relationship between the chiral strength of the unit structure and the asymmetric transmission characteristics is also discussed.The influence of the thickness of the dielectric and metal layers and the incident angle of the electromagnetic wave on the asymmetric transmission characteristics is examined.