Qureshi Ubaid Ur Rahman, Deng Bowen, Wu Xudong, Xiong Chenjie, Jalal Abdul, Khan M Ismail, Hu Bin
Opt Express. 2024 Sep 9;32(19):32836-32848. doi: 10.1364/OE.529311.
A tri-layer chiral metasurface with multi-functions of asymmetric transmission (AT), polarization conversion (PC) and circular dichroism (CD) is proposed in the terahertz (THz) range. Simulation results show that the metasurface is able to realize AT with more than 90% efficiency and PC fractional bandwidth of 80% over a frequency range of 0.15 to 0.35 THz. At 0.33 THz, it showcases the utmost CD of 58%. Through experimental measurements, the fabricated device demonstrate that the AT parameters exceed 35% in the frequency range of 0.24-0.33 THz. This broad frequency range represents a PC fractional bandwidth of 69% and reveals a prominent peak at 0.28 THz, wherein the transmission attains a value of 0.62. The proposed configuration exhibits CD, achieving 14% at 0.24 THz. Furthermore, the functionalities of AT, PC and CD are stable for changes in incident angle up to 60° for both linearly polarized and circularly polarized incident waves. Moreover, the experimental and measured results demonstrate that the proposed multilayer chiral metamaterial achieves multifunctionality for THz incident waves, offering promising implications for advancing THz communication bands.
提出了一种在太赫兹（THz）波段具有不对称传输（AT）、偏振转换（PC）和圆二色性（CD）多功能的三层手性超表面。仿真结果表明，该超表面能够在0.15至0.35太赫兹的频率范围内实现效率超过90%的不对称传输以及80%的偏振转换分数带宽。在0.33太赫兹时，其展现出高达58%的最大圆二色性。通过实验测量，所制备的器件表明在0.24 - 0.33太赫兹的频率范围内，不对称传输参数超过35%。这个较宽的频率范围代表了69%的偏振转换分数带宽，并在0.28太赫兹处显示出一个显著的峰值，其中传输值达到0.62。所提出的结构呈现出圆二色性，在0.24太赫兹时达到14%。此外，对于线偏振和圆偏振入射波，不对称传输、偏振转换和圆二色性的功能在入射角变化高达60°时都是稳定的。而且，实验和测量结果表明，所提出的多层手性超材料对太赫兹入射波实现了多功能性，为推进太赫兹通信频段提供了有前景的意义。
