Broadband Terahertz Near-Perfect Absorbers
Broadband Terahertz Near-Perfect Absorbers
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DOI：
10.1021/acsami.0c06162
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发表时间：
2020-07-22
影响因子：
9.5
通讯作者：
Xu, Xiangdong
中科院分区：
文献类型：
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作者：
Cheng, Xiaomeng;Huang, Rui;Xu, Xiangdong
宽带太赫兹 (THz) 吸收器在检测、调制、接收和成像设备中非常受欢迎。我们报告了一种具有近乎完美吸收能力的新型宽带太赫兹超表面的设计和成功实现。与传统的金属/电介质/金属三层结构不同，所设计的太赫兹吸收体在顶部多了一层金属层和电介质间隔物，两者的厚度均为200 nm。尽管总厚度增加了大约 7%，但近乎完美的太赫兹吸收带显着加宽了 4 倍，实现了 270 GHz 的宽带吸收。在这些超吸收体中，在宽入射角上也观察到了宽带、偏振不敏感和近乎完美的太赫兹吸收，其中电场和功率损耗主要集中在附加的薄介电层中。这种宽带太赫兹吸收是通过顶部和中间金属层之间的电磁耦合以及由此产生的谐振频率重叠来实现的。该策略可以适用于其他频谱整形设备。
Broadband terahertz (THz) absorbers are highly desired in detection, modulation, receiving, and imaging devices. We report the design and successful implementation of a novel broadband THz metasurface with a near-perfect absorption. Different from the traditional metal/dielectric/metal three-layer structures, the as-designed THz absorber has one more metal layer and a dielectric spacer on top, both of which are 200 nm thick. Although the total thickness increased by similar to 7%, the near-perfect THz absorption band significantly broadened by 4x, achieving a broadband absorption of 270 GHz. Broadband, polarization-insensitive, and near-perfect THz absorptions were also observed over wide incident angles in these meta-absorbers, where the electric field and power loss were mainly concentrated in the additional thin dielectric layer. Such a broadband THz absorption was achieved through electromagnetic coupling between the top and middle metal layers and the resultant overlapping of the resonance frequencies. This strategy can be adapted to other spectrum-shaping devices.