A Broadband Vortex Beam Generator Based on Single-Layer Hybrid Phase-Turning Metasurface

Area of Science:

• Electromagnetics and Optics
• Metamaterial Applications
• Wireless Communication

Background:

• Vortex beams with orbital angular momentum (OAM) are crucial for enhancing spectral efficiency and transmission capacity in communication systems.
• Metasurfaces offer a promising platform for manipulating electromagnetic waves due to their subwavelength structures and design flexibility.

Purpose of the Study:

• To design and demonstrate a single-layer metasurface capable of generating a broadband vortex beam with a specific OAM mode.
• To investigate the performance of the metasurface in terms of mode purity, bandwidth, gain, and crosstalk.

Main Methods:

• A hybrid phase-turning meta-atom combining resonance and geometric (Pancharatnam-Berry) phase modulation was designed.
• A single-layer metasurface was fabricated using the designed meta-atoms.
• The fabricated metasurface was experimentally measured to characterize its vortex beam generation capabilities.

Main Results:

• The metasurface successfully generated a linearly polarized broadband vortex beam of mode l = -1.
• Over 70% mode purity was achieved across a relative bandwidth of 38.57% (26.5 GHz to 40 GHz).
• The generator exhibited a wide 3 dB gain bandwidth and low crosstalk.

Conclusions:

• The proposed single-layer metasurface is an effective generator for broadband vortex beams with OAM.
• The demonstrated performance highlights significant application potential in vortex beam communication systems.
• This work contributes to the advancement of high-capacity wireless communication technologies.