IEEE Access (Jan 2020)

High-Performance Transmissive Broadband Vortex Beam Generator Based on Pancharatnam–Berry Metasurface

  • Yuzhou Ran,
  • Tong Cai,
  • Lihua Shi,
  • Jianbao Wang,
  • Jiangang Liang,
  • Shuran Wu,
  • Jie Li,
  • Yicheng Liu

DOI
https://doi.org/10.1109/ACCESS.2020.3002547
Journal volume & issue
Vol. 8
pp. 111802 – 111810

Abstract

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Vortex beam generators, particularly those operating in transmission mode, are extremely important in modern communication systems because they are believed to be an effective way to extend the capacity of a communication channel. However, current approaches have suffered from complex configurations, fixed operation modes, and low efficiency, particularly in a transmissive case. In this study, we propose a new strategy for improving the transmissive amplitude and bandwidth of metasurfaces by optimizing microstructures with a non-uniform thickness based on the transfer matrix method (TMM). As a result, our designed meta-atom can achieve a high transmission of greater than 0.9 within a wide frequency interval of 12.6–16.2 GHz. As a proof of concept, we designed a vortex beam generator with topological charge $l = 1$ using the designed meta-atom. We conducted near- and far-field experiments to characterize its performance, indicating that our meta-device can realize a pure vortex beam with an efficiency of higher than 82.1% at a central frequency of 15 GHz. Our findings will lay a theoretical foundation for studies on metasurfaces with a non-uniform thickness and provide a way to design high-performance meta-devices with broad bandwidths.

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