An End to All Your Internet Hassles

An Indian origin Engineering Professor at Boston University, Siddharth Ramachandran, has recently designed an optical fibre that may change the world of internet dramatically in the time to come.

‘Optical Vortices’, the technology that these fibers use, promises to increase bandwidth many folds, easing Internet congestion and video streaming.

The technology centres on donut-shaped laser light beams called optical vortices, in which the light twists like a tornado as it moves along the beam path, rather than in a straight line.

Widely studied in Atomic Physics, Quantum Optics and Molecular Biology, optical vortices (also known as Orbital Angular Momentum (OAM) beams) were thought to be unstable in fiber, until Professor Ramachandran designed an optical fiber that can propagate them.

In the paper in the journal Science, he and Alan Willner of University of Southern California, demonstrated the stability of the beams in optical fibre and also their potential to boost Internet bandwidth.   

Optical Fibre Technology: New Dimensions Added

"A few years ago, people in our community got together and saw this exponential growth of bandwidth demand and the slow growth of fiber. They weren't matching up. Service providers can put in more fiber optic lines, but that's a linear process, it's not exponential growth. We've added another degree of freedom to these fibers."

Traditionally, bandwidth has been enhanced by increasing the number of colours, or wavelengths of data-carrying laser signals — essentially streams of 0s and 1s — sent down an optical fiber, where the signals are processed according to colour.

An emerging strategy to boost bandwidth is to send the light through a fiber along distinctive paths, or modes, each carrying a cache of data from one end of the fiber to the other. Unlike the colours, however, data streams of 1s and 0s from different modes mix together; determining which data stream came from which source requires computationally intensive and energy-hungry digital signal processing algorithms.

Ramachandran’s and Willner’s approach combines both strategies, packing several colours into each mode, and using multiple modes.

In experiments in the study, the researchers created an OAM fiber with four modes (an optical fiber typically has two), and showed that for each OAM mode, they could send data through a one-kilometre fibre in 10 different colours, resulting in a transmission capacity of 1.6 terabits per second.

And unlike lots of fancy new research, this one is all but ready for use. One of the researchers involved in the project was Poul Kristensen, of OFSFitel, one of the world's largest fiber optic cable manufacturers. Ramachandran said that the OAM cables were created on OFSFitel's production floor.

"We're not just doing this for fun," he said. "This is actually production fiber. Service providers know they'll eventually have to do a next generation fiber run, the question is, should they start putting in new kinds of fiber?"

Ramachandran thinks they can!