中国物理B ›› 2022, Vol. 31 ›› Issue (10): 108701-108701.doi: 10.1088/1674-1056/ac70bd

• INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY • 上一篇    下一篇

Broadband and high efficiency terahertz metasurfaces for anomalous refraction and vortex beam generation

Wen-Yu Li(李文宇)1,2, Ran Sun(孙然)1, Jing-Yu Liu(刘靖宇)1, Tian-Hua Meng(孟田华)2, and Guo-Zhong Zhao(赵国忠)1,†   

  1. 1. Department of Physics, Capital Normal University, Beijing Key Laboratory for THz Spectroscopy and Imaging, Key Laboratory of THz Optoelectronics, Ministry of Education, Beijing 100048, China;
    2. Institute of Solid State Physics, Shanxi Datong University, Datong 037009, China
  • 收稿日期:2022-03-18 修回日期:2022-04-21 出版日期:2022-10-16 发布日期:2022-09-24
  • 通讯作者: Guo-Zhong Zhao E-mail:guozhong-zhao@cnu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 62071312), the National Key Research and Development Program of China (Grant No. 2021YFB3200100), the Important Research and Development Projects of Shanxi Province, China (Grant No. 201803D121083), and the Fund from the Shanxi Scholarship Council, China (Grant No. 2020-135).

Broadband and high efficiency terahertz metasurfaces for anomalous refraction and vortex beam generation

Wen-Yu Li(李文宇)1,2, Ran Sun(孙然)1, Jing-Yu Liu(刘靖宇)1, Tian-Hua Meng(孟田华)2, and Guo-Zhong Zhao(赵国忠)1,†   

  1. 1. Department of Physics, Capital Normal University, Beijing Key Laboratory for THz Spectroscopy and Imaging, Key Laboratory of THz Optoelectronics, Ministry of Education, Beijing 100048, China;
    2. Institute of Solid State Physics, Shanxi Datong University, Datong 037009, China
  • Received:2022-03-18 Revised:2022-04-21 Online:2022-10-16 Published:2022-09-24
  • Contact: Guo-Zhong Zhao E-mail:guozhong-zhao@cnu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 62071312), the National Key Research and Development Program of China (Grant No. 2021YFB3200100), the Important Research and Development Projects of Shanxi Province, China (Grant No. 201803D121083), and the Fund from the Shanxi Scholarship Council, China (Grant No. 2020-135).

摘要: The applications of metasurfaces are currently a highly active research field due to their extraordinary ability to manipulate electromagnetic waves. The ultra-thin characteristics of metasurfaces allow the miniaturization and integration of metasurface devices. However, these devices work typically under a low efficiency and narrow bandwidth condition. In this work, we design eight multilayered unit cells with similar amplitudes and a phase interval of π/4, which convert the polarization states of the terahertz (THz) waves between two orthogonal directions. The average cross-polarized transmission amplitudes of these cells are all around 0.9 in an ultra-broad frequency range from 0.5 THz to 1.4 THz. Furthermore, unit cells are used to construct both an ultra-thin anomalous refraction metalens and a vortex phase plate. Our simulation results show that the anomalous refraction for the transmitted linear polarization component is comparable to the theoretical prediction, and the maximum error is determined to be below 4.8%. The vortex phase plate can also generate an ideal terahertz vortex beam with a mode purity of 90% and more. The distributions of longitudinal electric field, intensity, and phase illustrate that the generated vortex beam has excellent propagation characteristics and a weak divergence. Simulations of the two types of metasurface devices, based on the eight unit cells, exhibit very high efficiencies in a wide bandwidth. Our research will assist in the improvement in the practical applications of metasurfaces. It also provides a reference for the design of high efficiency and broadband devices that are applied to other frequency ranges.

关键词: terahertz, metasurface, anomalous refraction, vortex beam generation

Abstract: The applications of metasurfaces are currently a highly active research field due to their extraordinary ability to manipulate electromagnetic waves. The ultra-thin characteristics of metasurfaces allow the miniaturization and integration of metasurface devices. However, these devices work typically under a low efficiency and narrow bandwidth condition. In this work, we design eight multilayered unit cells with similar amplitudes and a phase interval of π/4, which convert the polarization states of the terahertz (THz) waves between two orthogonal directions. The average cross-polarized transmission amplitudes of these cells are all around 0.9 in an ultra-broad frequency range from 0.5 THz to 1.4 THz. Furthermore, unit cells are used to construct both an ultra-thin anomalous refraction metalens and a vortex phase plate. Our simulation results show that the anomalous refraction for the transmitted linear polarization component is comparable to the theoretical prediction, and the maximum error is determined to be below 4.8%. The vortex phase plate can also generate an ideal terahertz vortex beam with a mode purity of 90% and more. The distributions of longitudinal electric field, intensity, and phase illustrate that the generated vortex beam has excellent propagation characteristics and a weak divergence. Simulations of the two types of metasurface devices, based on the eight unit cells, exhibit very high efficiencies in a wide bandwidth. Our research will assist in the improvement in the practical applications of metasurfaces. It also provides a reference for the design of high efficiency and broadband devices that are applied to other frequency ranges.

Key words: terahertz, metasurface, anomalous refraction, vortex beam generation

中图分类号: 

  • 87.50.U-
81.05.Xj (Metamaterials for chiral, bianisotropic and other complex media) 42.25.Gy (Edge and boundary effects; reflection and refraction) 74.25.Uv (Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses))