Spinning light on the nanoscale.

Light beams with orbital angular momentum have significant potential to transform many areas of modern photonics from imaging to classical and quantum communication systems. We design and experimentally demonstrate an ultracompact array of nanowaveguides with a circular graded distribution of channel diameters that coverts a conventional laser beam into a vortex with an orbital angular momentum. The proposed nanoscale beam converter is likely to enable a new generation of on-chip or all-fiber structured light applications.