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Terahertz (THz) wave usually refers to the electromagnetic wave with a frequency between 0.1—10.0 THz. It has potential applications in wireless communication, biomedical image processing, nondestructive testing, military radar, and other fields. However, owing to function limitation of the natural material, multifunctional terahertz devices are difficult to design and fabricate, which becomes a bottleneck for THz technology. The emergence of metamaterials fills the gap in the electromagnetic materials in the THz frequency band, and now they are widely used in THz functional devices, such as THz modulators, THz absorbers, THz filters, THz sensors, and THz slow-light devices. However, the above-mentioned THz devices all have a single function. For practical application, multifunction integrated THz devices have broader application prospects. As is well known, the Ge2Sb2Te5 (GST) is a typical phase transition material. Under excitation of light or electronic field, GST can realize a reversible phase transition between insulating state and metallic state. In order to achieve a switchable multifunctional THz device, in this work we design a THz metamaterial based on the phase transition material GST and realize a switchable function with slow-light and absorption functions. The THz metamaterial consists of a microstructure layer, which is composed of gold rings arranged periodically, and a GST thin film spaced by an SiO2 dielectric layer. When GST is in an insulating state, the two gold rings are coupled to each other under the excitation of the THz pulse. Then, we can observe the EIT-like effect. The THz pulses propagating in the metamaterial we proposed can be slowed down, and a maximum group delay of the THz pulse can reach 3.6 ps. However, when GST is in a metallic state, we can observe two absorption peaks in the spectrum of the proposed THz metamaterial, and the absorption rate is 97% at a frequency of 0.365 THz and 100% at a frequency of 0.609 THz. Furthermore, we also investigate the polarization properties of the proposed THz metamaterial, and find that it has polarization insensitive characteristic. When the polarization angle of the incident THz light pulse changes from 0° to 90°, the slow-light and absorption properties of the THz metamaterial are unaffected. The proposed THz metamaterial has potential applications in THz biomedical image processing, THz optical switching, and THz optical buffer.
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Keywords:
- metamaterials /
- terahertz /
- slow light /
- absorber /
- phase change materials
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[2] Yang X W, Zhao F 2022 Acta Opt. Sin. 42 0806002Google Scholar
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[4] Shen Y C, Lo T, Taday P F, Cole B E, Tribe W R, Kemp M C 2005 Appl. Phys. Lett. 86 241116Google Scholar
[5] Li H Y, Li Q, Xia Z W, Zhao Y P, Chen D Y Wang Q 2013 J. Infrared, Millimeter, Terahertz Waves 34 88Google Scholar
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[7] Seddon N, Bearpark T 2003 Science 302 1537Google Scholar
[8] Zhong Y J, Huang Y, Zhong S C 2021 Opt. Mater. 14 110996Google Scholar
[9] Cai H 2018 Adv. Opt. Mater. 6 1800257Google Scholar
[10] Zhu H L, Zhang Y, Ye L F, Li Y K, Xu Y H, Xu R 2020 Opt. Express 28 414039Google Scholar
[11] Hu F R, Wang H, Zhang X W, Xu X L, Jiang W Y, Rong Q, Zhao S, Jiang M Z, Zhang W T 2019 IEEE J. Sel. Top. Quantum Electron. 25 4700207Google Scholar
[12] Seo M, Park H R 2020 Adv. Opt. Mater. 8 1900662Google Scholar
[13] Cui W, Wang Y X, He Z H, He H 2021 Results Phys. 26 104356Google Scholar
[14] Gansel J K, Thiel M, Rill M S, Decker M, Bade K, Saile V, Freymann G V, Linden S, Wegener M 2009 Science 325 1513Google Scholar
[15] Makino K, Kato K, Saito Y, Fons P, Kolobov A V, Tominaga J J, Nakano T, Nakajima M 2019 J. Mater. Chem. C 7 8209Google Scholar
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[17] Guo L Y, Ma X H, Chang Z Q, Xu C L, Liao J, Zhang R 2021 J. Mater. Res. Technol 14 772Google Scholar
[18] Fabio A, Brian K, Dragoslav G, Nickolay V L, Gamani K 2012 Appl. Phys. Lett. 100 111104Google Scholar
[19] Sun H Y, Zhao L, Dai J S, Liang Y Y, Guo J P, Meng H Y, Liu H Z, Dai Q F, Wei Z C 2020 Nanomaterials 10 1359Google Scholar
[20] Galván A M, Hernández J G 2000 J. Appl. Phys. 87 760Google Scholar
[21] Manjappa M, Chiam S Y, Cong L Q, Bettiol A A, Zhang W L, Singh R J 2015 Appl. Phys. Lett. 106 181101Google Scholar
[22] Meng F Y, Wu Q, Erni D, Wu K, Lee J C 2012 IEEE Trans. Microwave Theory Tech. 60 3013Google Scholar
[23] Niakan N, Askari M, Zakery A 2012 J. Opt. Soc. Am. B 29 2329Google Scholar
[24] Sun H, Hu Y Z, Tang Y H, You J, zhou J H, Liu H Z, Zheng X 2020 Photonics Res. 8 263Google Scholar
[25] Bagcia F, Akaoglu B 2018 J. Appl. Phys. 123 173101Google Scholar
[26] Suna Y B, Shi Y P, Liu X Y, Song J M, Lia M P, Wang X D, Yang F H 2021 Nanoscale Adv. 3 4072Google Scholar
[27] Mattiucci N, Bloemer M J, Aközbek N, D’Aguanno G 2013 Sci. Rep. 3 3203Google Scholar
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图 2 (a) GST薄膜处于绝缘状态时, 外环、内环和双环结构的透射光谱图; (b)—(d) 0.453, 0.547, 0.834 THz处超材料结构的表面电流分布
Figure 2. (a) Transmission spectrum of outer ring, inner ring, and double ring structures with GST films in an insulating state; (b)–(d) surface current distribution of metamaterial structures at 0.453, 0.547, and 0.834 THz.
图 5 (a)—(c) SiO2层厚度h = 24 μm时, THz超材料结构的介电常数 (a)、磁导率(b)和等效阻抗(c); (d)不同SiO2层厚度时THz超材料结构的吸收光谱
Figure 5. (a)–(c) Permittivity(a), permeability (b) and equivalent impedance (c) of THz metamaterial structure at SiO2 layer thickness h = 24 μm; (d) absorption spectrum of THz metamaterial structure at different SiO2 layer thickness.
表 1 三种相态GST材料的Drude模型参数
Table 1. Drude model parameters of the GST materials for the three phases.
相态 ε τ σdc 非晶态(a-GST) 15.3 — 0 面心立方(c-GST) 38.2 1.61 382 六方(h-GST) 60.6 5.29 2230 -
[1] Tonouchi M 2007 Nat. Photonics 1 97Google Scholar
[2] Yang X W, Zhao F 2022 Acta Opt. Sin. 42 0806002Google Scholar
[3] Wang Y Y, Wang G Q, Xu D G, Jiang B Z, Ge M L, Wu L M, Yang C Y, Mu N, Wang S, Chang C, Chen T, Feng H, Yao J Q 2022 Acta Opt. Sin. 42 1017001Google Scholar
[4] Shen Y C, Lo T, Taday P F, Cole B E, Tribe W R, Kemp M C 2005 Appl. Phys. Lett. 86 241116Google Scholar
[5] Li H Y, Li Q, Xia Z W, Zhao Y P, Chen D Y Wang Q 2013 J. Infrared, Millimeter, Terahertz Waves 34 88Google Scholar
[6] Zhou J F, Zhang L, Tuttle G, Koschny T, Soukoulis C M 2006 Phys. Rev. B 73 041101Google Scholar
[7] Seddon N, Bearpark T 2003 Science 302 1537Google Scholar
[8] Zhong Y J, Huang Y, Zhong S C 2021 Opt. Mater. 14 110996Google Scholar
[9] Cai H 2018 Adv. Opt. Mater. 6 1800257Google Scholar
[10] Zhu H L, Zhang Y, Ye L F, Li Y K, Xu Y H, Xu R 2020 Opt. Express 28 414039Google Scholar
[11] Hu F R, Wang H, Zhang X W, Xu X L, Jiang W Y, Rong Q, Zhao S, Jiang M Z, Zhang W T 2019 IEEE J. Sel. Top. Quantum Electron. 25 4700207Google Scholar
[12] Seo M, Park H R 2020 Adv. Opt. Mater. 8 1900662Google Scholar
[13] Cui W, Wang Y X, He Z H, He H 2021 Results Phys. 26 104356Google Scholar
[14] Gansel J K, Thiel M, Rill M S, Decker M, Bade K, Saile V, Freymann G V, Linden S, Wegener M 2009 Science 325 1513Google Scholar
[15] Makino K, Kato K, Saito Y, Fons P, Kolobov A V, Tominaga J J, Nakano T, Nakajima M 2019 J. Mater. Chem. C 7 8209Google Scholar
[16] Zhou K, Nan J Y, Shen J B, Li Z P, Cao J C, Song Z T, Zhu M, He B Q, Yan M, Zeng H P, Li H 2021 APL Mater. 9 101113Google Scholar
[17] Guo L Y, Ma X H, Chang Z Q, Xu C L, Liao J, Zhang R 2021 J. Mater. Res. Technol 14 772Google Scholar
[18] Fabio A, Brian K, Dragoslav G, Nickolay V L, Gamani K 2012 Appl. Phys. Lett. 100 111104Google Scholar
[19] Sun H Y, Zhao L, Dai J S, Liang Y Y, Guo J P, Meng H Y, Liu H Z, Dai Q F, Wei Z C 2020 Nanomaterials 10 1359Google Scholar
[20] Galván A M, Hernández J G 2000 J. Appl. Phys. 87 760Google Scholar
[21] Manjappa M, Chiam S Y, Cong L Q, Bettiol A A, Zhang W L, Singh R J 2015 Appl. Phys. Lett. 106 181101Google Scholar
[22] Meng F Y, Wu Q, Erni D, Wu K, Lee J C 2012 IEEE Trans. Microwave Theory Tech. 60 3013Google Scholar
[23] Niakan N, Askari M, Zakery A 2012 J. Opt. Soc. Am. B 29 2329Google Scholar
[24] Sun H, Hu Y Z, Tang Y H, You J, zhou J H, Liu H Z, Zheng X 2020 Photonics Res. 8 263Google Scholar
[25] Bagcia F, Akaoglu B 2018 J. Appl. Phys. 123 173101Google Scholar
[26] Suna Y B, Shi Y P, Liu X Y, Song J M, Lia M P, Wang X D, Yang F H 2021 Nanoscale Adv. 3 4072Google Scholar
[27] Mattiucci N, Bloemer M J, Aközbek N, D’Aguanno G 2013 Sci. Rep. 3 3203Google Scholar
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