Dynamically tunable and polarization-insensitive dual-band terahertz metamaterial absorber based on TiNi shape memory alloy films
Dynamically tunable and polarization-insensitive dual-band terahertz metamaterial absorber based on TiNi shape memory alloy films
复制标题
基于TiNi形状记忆合金薄膜的动态可调且偏振不敏感的双波段太赫兹超材料吸收器
DOI：
10.1016/j.rinp.2021.104001
复制
发表时间：
2021
影响因子：
5.3
通讯作者：
Changlong Tan
中科院分区：
文献类型：
--
作者：
Kun Zhang;Tianyou Ma;Juan Liu;Xiaohua Tian;Jiachen Zhu;Changlong Tan
制约其发展和应用的一个关键问题是太赫兹领域动态可调谐器件的缺乏。本论文创新性地将形状记忆合金引入到太赫兹超材料吸收体的设计中。提出了一种优化的结构设计，使MMA具有良好的动态调谐、偏振不敏感和双波段吸收特性。在0.9982 THz和1.5328 THz处，其吸收率分别达到98.8%和96.8%。进一步研究了结构参数对吸收性能的影响，揭示了这两个吸收峰的形成机理。基于TiNi合金的马氏体相变，可以通过改变外部热场来动态调谐吸收峰到所需的工作频率。同时，由于结构的对称性，当垂直入射时，吸收体是偏振不敏感的，并且可以在很宽的入射角范围内保持优异的吸收性能。考虑到超窄带宽和高品质因子Q，我们讨论了峰值B的感知能力。发现B峰对周围介质折射率的微小变化敏感，表现出敏感能力。通过理论分析，该传感器的灵敏度可达0.88 THz/RIU，传感器的优值可达92.63。该工作为基于SMA的动态可调谐太赫兹光学器件的设计提供了一种新的思路。
A crucial point of restricting its development and application is the lack of dynamically tunable devices in the terahertz fields. In this work, shape memory alloys (SMAs) are innovatively introduced into the design of THz metamaterials absorber (MMA). An optimized structure design is proposed, and the MMA exhibits the perfect properties of dynamical tuning, polarization insensitivity, and dual-band absorption. In detail, two discrete resonance peaks can be detected, and their corresponding absorbance is up to 98.8% at 0.9982 THz and 96.8% at 1.5328 THz, respectively. The effect of structural parameters on the absorption performance is investigated further to reveal these two peaks' formation mechanism. Based on the martensitic transformation of TiNi alloy, the absorption peaks can be dynamically tuned to the desired operating frequencies through varying the external thermal field. Meanwhile, the absorber is polarization-insensitive when it is incident vertically due to the symmetry of the structure, and the excellent absorption performance can be maintained over a wide angular range of incidence. On account of the ultra-narrow bandwidth and the high-quality factorQ, we discuss the sensing ability of peak B. It can be found that peak B is sensitive to a minor change of the refractive indexnof surrounding media and shows sensing ability. Through theoretical analysis, the sensitivity of the sensor is up to 0.88 THz/RIU, and the sensor’s figure of merit can be up to 92.63. This work proposes a novel idea of the design of various SMAs-based dynamically tunable terahertz optical devices.