Researchers in the United States and Israel have created infinite-capacity wireless vortex beams that can carry 2.5 terabits per second – that's enough to transmit seven full Blu-ray movies every second. This may be the fastest wireless network ever created, a breakthrough that could revolutionize the development of faster wireless and fiber-optic networks.
Scientists have been "twisting" light since the 1970s. Light can be contorted around like a corkscrew around its axis of travel, causing the light waves at the axis itself to cancel each other out. This creates an "optical vortex" when projected onto a flat surface. This vortex can be assigned a number based on how many twists the light does in one wavelength – a number that's either positive or negative depending on the twist. The higher the number, the faster the light is twisting.
Scientists have been wanting to exploit this phenomenon for quite time, as a way of transmitting information. And now, it appears they've done it.
Writing in ExtremeTech, Sebastian Anthony explains:
These twisted signals use orbital angular momentum (OAM) to cram much more data into a single stream. In current state-of-the-art transmission protocols (WiFi, LTE, COFDM), we only modulate the spin angular momentum (SAM) of radio waves, not the OAM. If you picture the Earth, SAM is our planet spinning on its axis, while OAM is our movement around the Sun. Basically, the breakthrough here is that researchers have created a wireless network protocol that uses both OAM and SAM.
And until only a few months ago, it was thought that OAM might not even be possible. But a recent breakthrough by Bo Thide finally proved that it could be done, as his team transmitted an OAM radio signal over 1450 feet (442 meters). This insight set the stage for Alan Wilner and his team at the University of Southern California, NASA's JPL, and Tel Aviv University.
Wilner's team twisted together eight 300Gbps visible light data streams, each with its own level of OAM twist. The beams were bundled in two groups of four and passed through different polarization filters. One of the bundles was transmitted as a thin stream (much like the thread of a screw), while the others were transmitted around the outside. The data beam was then transmitted over open space and untwisted at the receiving end.
This news is particularly exciting for those developing wireless networks because they've largely used up all the useful spectrum. Since the OAM model allows for an apparent infinite number of conventional transmission protocols without using any more spectrum, this would seem to provide an immediate solution.
Currently, the researchers are only able to transmit the data beam across a one meter distance. The next step for the team is to find a way to send their beams considerably farther. They're thinking that, for high capacity work, that 1km links would do the trick. But they're also contemplating the prospect of long-distance satellite-to-satellite communications in space.
The entire paper is available at Nature.
Top image via Shutterstock.com/Emelyanov. Inset images via ExtremeTech and Nature.