Twisted light transmits data across Vienna

BBC : Twisting light, which involves manipulating its orbital angular momentum, has been done since the 1990s. When researchers add a twist to polarized light, they provide photons with an infinite amount of possible orientations. The technique has been used to encode more information on each photon over fiber optics, and now Mario Krenn of the University of Vienna and his colleagues have transmitted twisted light through the air. They sent a green laser through a controlled LCD that applied a twist to the photons, which were then detected 3 km away. At the detector, the beam became a ring of dots, the arrangement of which changed depending on the amount of twist. The researchers then defined 16 of those patterns to correspond with 16 shades of gray and transmitted a series of grayscale images via the laser. The detector and computer program to reassemble the images were able to reproduce the transmitted images with just a 1.7% error rate.