• Acta Physica Sinica
  • Vol. 68, Issue 10, 104203-1 (2019)
Shao-He Li, Jiu-Sheng Li*, and Jian-Zhong Sun
DOI: 10.7498/aps.68.20190032 Cite this Article
Shao-He Li, Jiu-Sheng Li, Jian-Zhong Sun. Terahertz frequency coding metasurface[J]. Acta Physica Sinica, 2019, 68(10): 104203-1 Copy Citation Text show less

Abstract

Metasurface is an artificial structure composed of sub-wavelength units which can realize the arbitrary control of electromagnetic wave energy by coding and arranging metasurface. Unlike the previous coding metasurface with a fixed phase difference of the neighbor coding unit cells, the frequency coding metasurface possesses the main feature that it has the linear change phase difference and different phase sensitivities in the whole working frequency band of the digital unit cells. And it can flexibly control the reflected terahertz waves to the numerous directions by changing the working frequency without redesigning the coding metasurface structure. In this paper, the frequency coding metasurfaces are designed by using four herringbone unit cells with the same shape and different sizes. They have the same phase response at the initial frequency and the different phase sensitivities throughout the frequency band. To describe the frequency coding characteristics of the unit cells, the digital numbers "0" and "1" are used to represent the low phase sensitivity and high phase sensitivity, respectively. Using the frequency digital coding, it can control the electromagnetic wave energy radiations by a single digital coding metasurface without changing the spatial coding pattern. By the combination of the spatial coding and frequency coding, It can manipulate the electromagnetic wave energy radiations more flexibly. We demonstrate 1-bit, 2-bit periodic frequency coding metasurfaces and 2-bit non-periodic frequency coding metasurface. They are all designed in the pre-designed coding sequence to control the electromagnetic wave energy radiations. Numerically simulated results confirm that the frequency coding metasurface can flexibly control the reflected terahertz waves to the numerous directions by changing the working frequency without redesigning the coding metasurface structure. Additionally, the number of the backward diffusion-like scattering beam increases with the change of frequency for the 2-bit random terahertz frequency coding metasurface. It has a good dispersion effect on the main lobe energy of terahertz wave radiation. The radar cross section can be reduced effectively, and the maximum value of radar cross section reduction can reach 29 dB in the direction of θ = 0, φ = 0. It has a great application value in the terahertz wave cloaking.
Shao-He Li, Jiu-Sheng Li, Jian-Zhong Sun. Terahertz frequency coding metasurface[J]. Acta Physica Sinica, 2019, 68(10): 104203-1
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