Twisted Light Boosts Space Communication
Lab tests of twisted light beams could boost deep-space communcations. This image shows the laser communication system aboard NASA's Mars Telecommunications Orbiter.
CREDIT: NASA | Jet Propulsion Laboratory
Twisted light beams have opened the door for wireless communication 85,000 times faster than broadband Internet speeds. The breakthrough could allow NASA missions or military space satellites to exchange data at ultrahigh speeds.
Lab tests have shown how twisted laser beams can transmit data at speeds up to 2.56 terabits per second — roughly the equivalent of beaming 70 DVDs worth of data in a single second through free space. Such speed easily put broadband Internet's 30 megabits per second to shame.
"We didn't invent the twisting of light, but we took the concept and ramped it up to a terabit-per-second," said Alan Willner, electrical engineering professor at the University of Southern California in Los Angeles.
The international team hailing from the U.S., China, Pakistan and Israel used beam-twisting "phase holograms" that are able to twist light beams into a helical shape similar to that of DNA. Each beam's individual twist can effectively create the equivalent of a new data stream channel — similar to a radio having separate channels — without the need for more bandwidth.
The lab test beamed the data across open space rather than through fiber-optic cables, so that researchers could simulate space communication between satellites. Such testing had funding from the U.S. military's Defense Advance Research Projects Agency (DARPA) under its "Information in a Photon" program. [Secret Codes Ready to Take Quantum Leap in Space]
The twisted light concept remains limited to deep space missions or near-Earth satellite communication because of the Earth's atmospheric interference, but the technology of adaptive optics can help offset such interference to some degree. Such free-space beaming could also work over short distances on Earth.
But the concept could someday also boost data speeds over fiber-optic cables — Boston University researchers have already tested the method in a fiber ring stretching 0.6 miles (1 kilometer).
Jian Wang, a professor at Huazhong University of Science and Technology in China, was lead author on the new research paper detailed in the June 24 issue of the journal Nature Photonics.