Chiral metasurfaces guide twisted light into free space

Light can carry angular momentum in two distinct ways. One comes from polarization, which describes how the electric field rotates. The other comes from the shape of the wavefront itself, which can twist like a corkscrew as it travels.

This second form, known as orbital angular momentum, has attracted wide interest because it allows light to encode information, interact with matter in new ways, and probe physical and biological systems. Despite this promise, producing well-defined twisted light in free space remains technically challenging, especially when the light originates from small or lo