Dual-band vortex beam generation with different OAM modes using single-layer metasurface.

Area of Science:

• Electromagnetics
• Metamaterials
• Optical Engineering

Background:

• Orbital angular momentum (OAM) vortex waves offer significant potential for increasing communication capacity.
• Metasurfaces provide a powerful platform for manipulating electromagnetic waves, including OAM vortex beams.

Purpose of the Study:

• To propose and demonstrate a single-layer metasurface capable of generating vortex beams with different OAM modes and polarizations at two distinct frequency bands.
• To independently control OAM beam properties at separate frequencies using a hybrid phase modulation approach.

Main Methods:

• Designing a single-layer metasurface integrating resonant phase cells and geometric (Pancharatnam-Berry) phase cells.
• Utilizing resonant phase cells for OAM beam generation at 5.2 GHz with a topological charge of +1 under linear polarization.
• Employing rotated geometric phase cells for OAM beam generation at 10.5–12 GHz with a topological charge of +2 under left-handed circular polarization (LHCP).

Main Results:

• The metasurface successfully generated OAM beams with a topological charge of +1 at 5.2 GHz.
• The metasurface also generated deflected OAM beams with a topological charge of +2 at 10.5–12 GHz.
• Both simulated and experimental results confirmed the good performance of the single-layer metasurface across the two frequency bands.

Conclusions:

• A versatile single-layer metasurface has been developed for generating OAM vortex beams with tunable properties.
• This metasurface demonstrates independent control of OAM modes and polarizations at distinct frequencies, paving the way for advanced communication systems.
• The hybrid phase modulation approach offers a promising strategy for multi-band OAM beam generation.