Holographic-Inspired Multiple Circularly Polarized Vortex-Beam Generation with Flexible Topological Charges and Beam Directions

Exploiting the orbital angular momentum (OAM) of light in applications has emerged as a key subject in optics and photonics. Here the authors discuss a holographic technique in the context of generating radio waves that carry OAM. Using suitable reflectarray patterns, a linearly polarized plane wave can be converted to a vortex beam with a spiral phase profile over a wide frequency range---or to multiple OAM beams with flexible beam directions, topological charges, and polarization states. These results are rather interesting for $e.g.$ expanding the capacity of wireless communication systems.