Fiber-optic cables that deliver Internet service are almost filled to the brim with data, but a novel experiment has demonstrated that they may be able to carry much more. By changing a property called spin of the light waves that transmit information, researchers have discovered a way to not only store more information, but send it over long distances reliably.
The research comes by way of a new paper, published in this week's issue of Science. "The Internet has been growing at an exponential rate," Siddharth Ramachandran, associate professor of electrical and computer engineering at Boston University and co-author of the paper, told TechNewsDaily.
"Fiber-optic transmission lines and fiber-optic communications have been the backbone that serves this bandwidth, but unfortunately, it has not been growing as fast as the demand has been growing," he added.
Internet providers deliver service through fiber-optic cables: extremely thin glass or plastic tubes that transmit light. Since light is the fastest phenomenon in the universe and contains many different wavelengths, fiber optics can deliver tons of data at almost instantaneous speeds.
"In fiber optics, we can send light at different colors and keep them separate at the end of the line," Ramachandran said. In the past, when engineers wanted to send more information than can be handled by the current crop of colors, "we would just add another color [and] call it multiplexing."
Multiplexing is a process in which a "fast" connection — like a fiber-optic cable — transmits a jumble of data to a decoding device. This device then transmits clear information to computers via "slow" connections, like Ethernet cables.
There is a limit to the number of colors that can be sent down a fiber, however, which meant that providers have already almost saturated the fiber-optic cables with information. To address this issue, Ramachandran and his team applied a principle called "orbital angular momentum" (OAM) to spin fiber-optic photons in a different fashion and fit more data in transmissions.
Applying OAM to photons creates a number of new "spatial modes," which essentially act as channels to contain data. "[Photons] move corkscrew down the fiber," Ramachandran said. "If we design the fiber properly, we can make these modes very stable."
The experiment demonstrated much more than stability. OAM-treated fibers successfully transmitted data across 1.1 km of cable with a speed of 400 gigabits per second across 4 discrete channels. While the research is a long way from reaching consumers, Ramachandran foresees numerous everyday applications. [See also: Top 10 Life-Changing Inventions ]
"Smartphones and HDTVs require a huge [amount of] bandwidth," he said. "In order for more apps to develop in that space, one would need bandwidth to be scaling at an exponential rate." If engineers can apply OAM to discover additional fiber-optic channels, bandwidth and speeds can continue to increase, and more people can use broadband.
Although this research deals with terrestrial Internet connections, mobile networks are facing a similar problem: The air is running out of viable data transmission frequencies. Ramachandran foresees applications for OAM in this space as well.
"In free space, there are multiple ways by which one could use OAM," he said. "At the receiving end, I can very easily detect and figure out what the OAM state is, and from a data communications standpoint … I can send it into a receiver and decode the 1s and 0s."
As more of the world adopts broadband Internet, making room for new data channels will be more important than ever. If this experiment is any indication, OAM may play a pivotal role in keeping fiber optics fast and efficient.
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