Abstract-Controlling the Bandwidth of Terahertz Low-Scattering Metasurfaces

1. Jie Zhao^1,2, 
2. Qiang Cheng^1,3,*, 
3. Xin Ke Wang⁴, 
4. Min Jie Yuan⁴, 
5. Xiao Zhou^1,2, 
6. Xiao Jian Fu^1,2, 
7. Mei Qing Qi^1,2, 
8. Shuo Liu^1,2,
9. Hai Bin Chen^1,2, 
10. Yan Zhang^3,4 and
11. Tie Jun Cui^1,3,*

Version of Record online: 11 JUL 2016

DOI: 10.1002/adom.201600202

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

http://onlinelibrary.wiley.com/doi/10.1002/adom.201600202/abstract

Low-scattering metasurfaces in the terahertz region can benefit a number of applications such as imaging, radar, and novel light sources. Such metasurfaces can efficiently suppress specular reflection and diffuse the energy that comes back without preferred direction. However, the accurate bandwidth control of low-scattering metasurfaces is still a main issue to be investigated. To solve the problem, here a new strategy to realize the low-scattering metasurfaces with desired bandwidths is proposed. Different from the earlier work, the current design is carried out within a broad spectrum instead of at a single frequency, giving rise to the arbitrarily desired bandwidth. Three basic elements are proposed to construct the new metasurface, and the diffuse reflection feature can be attributed to their destructive interferences with the change of operating frequency. The intrinsic loss of the meta-atoms is also taken into account to make the theoretical model more accurate in the practical design. Excellent scattering-suppression features are observed in the predefined frequency bands in both simulated and experimental results, which have very good agreements with the theoretical predictions.

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-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.