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摘要

介绍了一种新型石墨烯太赫兹结构, 其周期单元包括一条长石墨烯单层带和两条短石墨烯单层带. 通过短石墨烯带所激发的明模式与长石墨烯带所激发的暗模式的相消干涉, 该结构产生了等离激元诱导透明效应. 利用耦合模理论推导了此效应的产生机理, 所得结果与时域有限差分方法的仿真值高度一致. 该结构除了具有外部动态可调性之外, 还具有十分出色的传感性能, 最大灵敏度和品质因子分别可达1.457 THz/RIU和30.5652. 此外, 提高结构中石墨烯的费米能级和载流子迁移率有助于增强慢光效应, 其中载流子迁移率的增强效果尤为明显. 当载流子迁移率从0.75 m ²/(V⋅s)提高到2.0 m ²/(V⋅s)时, 结构的群折射率从456增至1010. 本研究可为太赫兹波段传感器件和慢光器件的发展提供理论和概念框架.

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Abstract

In this work, Ansys FDTD is used to design and simulate a terahertz metamaterial structure based on periodic continuous pattern graphene monolayer, and the high-quality PIT phenomena are obtained by continuously adjusting structural parameters. To validate the designed structure, the simulated transmission curve (reflection curve) obtained is compared with the theoretical transmission curve (reflection curve) derived from coupled-mode theory. It is observed that these two results exhibit a remarkably high degree of overlap. The resonant frequency and Fermi energy reveals a perfect linear correlation between them with the resonant frequency increasing proportionally with Fermi energy increasing. Dynamic tuning of PIT can be realized by adjusting the Fermi energy of graphene. For a more in-depth study of its sensing characteristics, the structure is placed in different environments. As the refractive index of the detection medium increases, the resonant frequency gradually decreases, demonstrating a redshift phenomenon. By manipulating the resonant frequency of the PIT sensor, the selective detection of specific target can berealized. After analyzing the sensitivity and FOM values of the structure, it is found that the maximum sensitivity is 1.457 THz/RIU. At a resonant frequency of 6.8174 THz, FOM reaches 30.5652. In summary, the sensor structure designed in this work has dual frequency sensing characteristics and can be used for dual frequency detection. Moreover, compared with other sensor structures, it demonstrates superior sensing performance. Additionally, in studying the slow light effect of the structure, it is found that as the Fermi energy increases, the group index and phase shift at the transparency window continue to increase. At the Fermi energy of 1.2 eV, the group index reaches a high value of 584. This is because in the PIT phenomenon, transparent peaks are formed due to multimodal coupling. This coupling will significantly improve the dispersion characteristics near the transparent peak, resulting in a large group index near the transparent peak. Furthermore, with the increase of carrier mobility, the group index and phase shift of the structure also gradually increase. At a carrier mobility of 0.75 m²/(V·s), the group refractive index is 456, and reaches 1010 at 2.0 m²/(V·s). In this study, the slow-light performance of graphene structure can be optimized through jointly adjusting the Fermi energy and carrier mobility. This research provides theoretical support and methods for designing advanced graphene-based sensors and devices for slow-light applications.

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作者及机构信息

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通信作者:许辉,1067980351@qq.com; 陈智全,zqchen0106@qq.com

基金项目:湘江实验室重点项目(批准号: 23XJ02001)、湖南省自然科学基金(批准号: 2023JJ40218, 2022JJ30201)、长沙市自然科学基金(批准号: kq2202298)和湖南省教育厅科研基金(批准号: 21B0574, 21B0556)资助的课题.

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Corresponding author:Xu Hui,1067980351@qq.com; Chen Zhi-Quan,zqchen0106@qq.com

Funds:Project supported by the Key Project of Xiangjiang Laboratory, China (Grant No. 23XJ02001), the Natural Science Foundation of Hunan Province, China (Grant No. 2023JJ40218, 2022JJ30201), the Changsha Municipal Natural Science Foundation, China (Grant No. kq2202298), and the Scientific Research Foundation of Hunan Provincial Education Department, China (Grant No. 21B0574, 21B0556).

文章全文: translate this paragraph

参考文献

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施引文献

下载: 全尺寸图片幻灯片

E_f/eV	γ₁/(10¹²rad·s^–1)	γ₂/(10¹²rad·s^–1)	$\frac{\gamma_1- \gamma_2}{2}$/(10¹¹rad·s^–1)	μ/(10¹¹rad·s^–1)
0.8	2.0899	1.2955	3.972	2.6
0.9	2.1826	1.2772	4.527	2.6
1.0	2.2656	1.2670	4.993	2.6
1.1	2.3394	1.26	5.397	2.6
1.2	2.4304	1.2496	5.904	2.6

下载: 导出CSV

Δf₁/THz	Δf₂/THz	S₁/(THz·RIU^–1)	S₂/(THz·RIU^–1)
0.0689	0.1444	0.689	1.444
0.0689	0.1456	0.689	1.456
0.0663	0.1456	0.663	1.456
0.0663	0.1457	0.663	1.457
0.0677	0.1430	0.677	1.430
0.0637	0.1404	0.637	1.404

下载: 导出CSV

	Our work	Ref. [48]	Ref. [49]	Ref. [50]	Ref. [2]
FOM	30.5652	21.92	6.111	24	23.61

下载: 导出CSV

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