Abstract-A polarization-insensitive broadband terahertz absorber with a multilayer structure

Hai-Feng Zhang, Jia-Xuan Liu, Jing Yang, Hao Zhang,Hai-Ming Li,


https://www.sciencedirect.com/science/article/pii/S2211379718324306

In this paper, a polarization-insensitive broadband terahertz absorber (PBTA) is presented and demonstrated, which can realize a polarization-insensitive, and broadband perfect absorption in the terahertz regime. By simulation, the polarization-insensitive broadband absorption is over 90%, which runs from 4.904THz to 6.632THz (the relative bandwidth is 29.96%), and the obtained absorption remains a good absorption performance with a wide incident angle for both TE and TM waves. The surface current distributions, power loss densities, electric and magnetic field distributions of such an absorber are investigated to figure out the physical mechanism of such a PBTA. The effects structure parameters on the absorption performance are also studied, which will be a guiding to realize a PBTA. The simulated results show that the proposed multilayer structure can help to design a PBTA.

Abstract-An broadband terahertz metamaterial filter based on multiplexed metallic bar resonators

Zijie Dai, Jing Yang, Qiang Su, Pengfei Qi, Dan Lu, Cheng Gong, Lu Sun, and Weiwei Liu

https://www.osapublishing.org/abstract.cfm?uri=CLEO_QELS-2018-JTh2A.178

An ultrabroad terahertz metamaterial filter based on multiplexed metallic bar resonators is designed and fabricated. The bandwidth of terahertz filter can be significantly broadened by the multiplexed configurations.

© 2018 The Author(s)

Abstract-Tunable reflecting terahertz filter based on chirped metamaterial structure

• Jing Yang
• , Cheng Gong
• , Lu Sun
• , Ping Chen
• , Lie Lin
•  & Weiwei Liu

http://www.nature.com/articles/srep38732
Tunable reflecting terahertz bandstop filter based on chirped metamaterial structure is demonstrated by numerical simulation. In the metamaterial, the metal bars are concatenated to silicon bars with different lengths. By varying the conductivity of the silicon bars, the reflectivity, central frequency and bandwidth of the metamaterial could be tuned. Light illumination could be introduced to change the conductivity of the silicon bars. Numerical simulations also show that the chirped metamaterial structure is insensitive to the incident angle and polarization-dependent. The proposed chirped metamaterial structure can be operated as a tunable bandstop filter whose modulation depth, bandwidth, shape factor and center frequency can be controlled by light pumping.

Abstract-3D printed low-loss THz waveguide based on Kagome photonic crystal structure

Jing Yang, Jiayu Zhao, Cheng Gong, Haolin Tian, Lu Sun, Ping Chen, Lie Lin, and Weiwei Liu

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-20-22454

A low-loss hollow core terahertz waveguide based on Kagome photonic crystal structure has been designed and fabricated by 3D printing. The 3D printed waveguide has been characterized by using THz time-domain spectroscopy. The results demonstrate that the obtained waveguide features average power propagation loss of 0.02 cm−1 for 0.2-1.0 THz (the minimum is about 0.002 cm−1 at 0.75 THz). More interesting, it could be simply mechanically spliced without any additional alignment, while maintaining the excellent performance. The 3D printing technique will be a promising solution to fabricate Kagome THz waveguide with well controllable characteristics and low cost.

© 2016 Optical Society of America

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Abstract-Broadband terahertz metamaterial absorber based on sectional asymmetric structures

Cheng Gong, Mingzhou Zhan, Jing Yang, Zhigang Wang, Haitao Liu, Yuejin Zhao & Weiwei Liu

http://www.nature.com/articles/srep32466

We suggest and demonstrate the concept and design of sectional asymmetric structures which can manipulate the metamaterial absorber’s working bandwidth with maintaining the other inherent advantages. As an example, a broadband terahertz perfect absorber is designed to confirm its effectiveness. The absorber’s each cell integrates four sectional asymmetric rings, and the entire structure composed of Au and Si3N4 is only 1.9 μm thick. The simulation results show the bandwidth with absorptivity being larger than 90% is extended by about 2.8 times comparing with the conventional square ring absorber. The composable small cell, ultra-thin, and broadband absorption with polarization and incident angle insensitivity will make the absorber suitable for the applications of focal plane array terahertz imaging.

Abstract-Broadband, wide-angle, low-scattering terahertz wave by a flexible 2-bit coding metasurface

Xin Yan, Lanju Liang, Jing Yang, Weiwei Liu, Xin Ding, Degang Xu, Yating Zhang, Tiejun Cui, and Jianquan Yao
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-22-29128

Abstract: Expanding bandwidths and arbitrary control of technology remain key issues in the field of electromagnetic waves, especially in terahertz (THz) wave. In this paper, we propose a novel method to achieve broadband low-scattering THz characteristics with wide-angle and polarization independence by a 2-bit flexible and nonabsorptive coding metasurface. The coding metasurface is composed of four digital elements based on double cross metallic line for “00”, “01”, “10”, and “11.” The reflection phase difference of neighboring elements is about 90° over a broad THz frequency band and wide incident angles. The low scattering coefficients below –10 dB were achieved over a wide frequency band from 0.8 THz to 1.5 THz when the incident angle is less than 50° by coding the four elements sequences. This superior property is maintained when the flexible coding metasurface is wrapped around a metallic cylinder with different dimensions. These results present a novel method to control THz waves freely and demonstrate significant scientific value in practical applications.

© 2015 Optical Society of America

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Abstract-Metasurfaces: Terahertz Broadband Low-Reflection Metasurface by Controlling Phase Distributions

                             

1. Di Sha Dong¹, 
2. Jing Yang², 
3. Qiang Cheng^1,*, 
4. Jie Zhao¹, 
5. Li Hua Gao¹, 
6. Shao Jie Ma³, 
7. Shuo Liu¹, 
8. Hai Bin Chen¹, 
9. Qiong He³,
10. Wei Wei Liu², 
11. Zheyu Fang⁴, 
12. Lei Zhou³and
13. Tie Jun Cui^1,*

Article first published online: 20 OCT 2015

DOI: 10.1002/adom.201570065

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA

http://onlinelibrary.wiley.com/doi/10.1002/adom.201570065/abstract

A single-layered metasurface is proposed by Q. Cheng, T. J. Cui, and co-workers to realize broadband diffusion at terahertz frequencies based on the destructive interference from a number of sub-wavelength elements. On page 1405, two kinds of elements are used to achieve full phase range and a linear phase response. The scattered waves can be efficiently manipulated to disperse into nearly all directions, resulting in extremely low back-scattering. The metasurface shows excellent angular independence toward incident waves across a broad spectrum.

Abstract-Broadband diffusion of terahertz waves by multi-bit coding metasurfaces

Li-Hua Gao¹, Qiang Cheng^1,2, Jing Yang³, Shao-Jie Ma⁴, Jie Zhao¹, Shuo Liu¹, Hai-Bing Chen¹, Qiong He⁴, Wei-Xiang Jiang^1,2, Hui-Feng Ma^1,2, Qi-Ye Wen^2,5, Lan-Ju Liang^6,7, Biao-Bing Jin^2,6, Wei-Wei Liu^2,3, Lei Zhou⁴, Jian-Quan Yao⁷, Pei-Heng Wu⁶ and Tie-Jun Cui^1,2

1. ¹State Key Laboratory of Millimeter Waves, Department of Radio Engineering, Southeast University, Nanjing 210096, China
2. ²Cooperative Innovation Centre of Terahertz Science, No. 4, Section 2, North Jianshe Road, Chengdu 610054, China
3. ³Institute of Modern Optics, Key Laboratory of Optical Information Science and Technology (Ministry of Education), Nankai University, Tianjin 300071, China
4. ⁴State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Fudan University, Shanghai 200433, China
5. ⁵State Key Laboratory of Electronic Films and Integrated Devices, University of Electronic Science and Technology, Chengdu 610054, China
6. ⁶Research Institute of Superconductor Electronics (RISE), School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
7. ⁷Institute of Lasers and Optoelectronics, College of Precision Instrument and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China

Correspondence: Q Cheng, Email: qiangcheng@seu.edu.cn; TJ Cui, Email: tjcui@seu.edu.cn

Received 16 January 2015; Revised 23 April 2015; Accepted 26 April 2015

http://www.nature.com/lsa/journal/v4/n9/full/lsa201597a.html

The terahertz region is a special region of the electromagnetic spectrum that incorporates the advantages of both microwaves and infrared light waves. In the past decade, metamaterials with effective medium parameters or gradient phases have been studied to control terahertz waves and realize functional devices. Here, we present a new approach to manipulate terahertz waves by using coding metasurfaces that are composed of digital coding elements. We propose a general coding unit based on a Minkowski closed-loop particle that is capable of generating 1-bit coding (with two phase states of 0 and 180°), 2-bit coding (with four phase states of 0, 90°, 180°, and 270°), and multi-bit coding elements in the terahertz frequencies by using different geometric scales. We show that multi-bit coding metasurfaces have strong abilities to control terahertz waves by designing-specific coding sequences. As an application, we demonstrate a new scattering strategy of terahertz waves—broadband and wide-angle diffusion—using a 2-bit coding metasurface with a special coding design and verify it by both numerical simulations and experiments. The presented method opens a new route to reducing the scattering of terahertz waves.

Abstract-Anomalous Terahertz Reflection and Scattering by Flexible and Conformal Coding Metamaterials

1. Lanju Liang¹, 
2. Meiqing Qi², 
3. Jing Yang³,
4. Xiaopeng Shen², 
5. Jiquan Zhai¹, 
6. Weizong Xu⁴, 
7. Biaobing Jin^1,5,*, 
8. Weiwei Liu^3,5,*,
9. Yijun Feng⁴, 
10. Caihong Zhang¹, 
11. Hai Lu⁴,
12. Hou-Tong Chen⁶, 
13. Lin Kang¹, 
14. Weiwei Xu¹,
15. Jian Chen^1,5, 
16. Tie Jun Cui^2,5,*, 
17. Peiheng Wu¹ and
18. Shenggang Liu^5,7

Article first published online: 30 JUN 2015

http://onlinelibrary.wiley.com/doi/10.1002/adom.201500206/abstract;jsessionid=75D9087BA4464D14DC4C0EA2F158CD85.f03t01?userIsAuthenticated=false&deniedAccessCustomisedMessage=

DOI: 10.1002/adom.201500206

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Arbitrary control of terahertz (THz) waves remains a significant challenge although it promises many important applications. Here, a method to tailor the reflection and scattering of THz waves in an anomalous manner by using 1-bit coding metamaterials is presented. Specific coding sequences result in various THz far-field reflection and scattering patterns, ranging from a single beam to two, three, and numerous beams, which depart obviously from the ordinary Snell's law of reflection. By optimizing the coding sequences, a wideband THz thin film metamaterial with extremely low specular reflection, due to the scattering of the incident wave into various directions, is demonstrated. As a result, the reflection from a flat and flexible metamaterial can be nearly uniformly distributed in the half space with small intensity at each specific direction, manifesting a diffuse reflection from a rough surface. Both simulation and experimental results show that a reflectivity less than −10 dB is achieved over a wide frequency range from 0.8 to 1.4 THz, and it is insensitive to the polarization of the incident wave. This work reveals new opportunities arising from coding metamaterials in effective manipulation of THz wave propagation and may offer widespread applications.

Abstract-Terahertz Broadband Low-Reflection Metasurface by Controlling Phase Distributions

1. Di Sha Dong¹, 
2. Jing Yang², 
3. Qiang Cheng^1,*, 
4. Jie Zhao¹, 
5. Li Hua Gao¹, 
6. Shao Jie Ma³, 
7. Shuo Liu¹, 
8. Hai Bin Chen¹, 
9. Qiong He³,
10. Wei Wei Liu², 
11. Zheyu Fang⁴, 
12. Lei Zhou³and
13. Tie Jun Cui^1,*
14. Article first published online: 5 JUN 2015

DOI: 10.1002/adom.201500156

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

http://onlinelibrary.wiley.com/doi/10.1002/adom.201500156/abstract

Recently, reflectionless or low-reflection surfaces made of subwavelength structures have been of broad interest in practical engineering. Here, a single-layer terahertz metasurface is proposed to produce ultralow reflections across a broad-frequency spectrum and wide incidence angles by controlling the reflection phases of subwavelength structures. To enable full control of the phase range in a continuous band, a combination of two different subwavelength elements are employed, both of which exhibit weak interactions with the incident terahertz waves, thereby showing high local reflectivities near the operating frequency. An optimization method is utilized to determine the array pattern with the minimum overall reflections under the illumination of plane waves. Both numerical simulations and experimental results demonstrate ultralow reflections of terahertz waves by the metasurface over a broad frequency band and wide incidence angles. By using the proposed metasurface, the far-field scattering patterns of metallic objects can be efficiently controlled, which opens up a new route for low-reflection surface designs in the terahertz spectrum.