Improving the flow of the fibre freeway

The breakthrough uses commercial components manufactured in Australia to optimize the efficiency of the existing optical fibre networks that connect towns and cities. It could dramatically boost the overall performance of networks like the NBN while reducing costs.

The team of researchers from the Centre of Excellence for Ultrahigh bandwidth Devices for Optical Systems with Dr. Jochen Schröder, Dr. Joel Carpenter and Professor Benjamin Eggleton from the University of Sydney and Dr, Liang Du and Professor Arthur Lowery from Monash University, transmitted a signal of 10 terabits per second over more than 850 km, by reprogramming a network component (known as a Wavelength Selective Switch) to work with data encoding technology that makes more efficient use of the available data channels. As a comparison, ADSL 2+ speeds are commonly around six megabits per second.

Their exciting findings were presented as a postdeadline paper at the world's largest optical communications conference, Optical Fiber Communications (OFC), in California on 22 March. The purpose of postdeadline papers is to give conference delegates the opportunity to hear breakthrough results in rapidly advancing areas. Dr Carpenter said the team was delighted that the research had been selected as a postdeadline paper from a competitive field even after submissions had closed. It had therefore been judged to be cutting edge and compelling in its timeliness.

“We are using existing infrastructure in a totally new way to push networks to the highest performance” said Dr Schröder. Professor Lowery added that by using the switch, the signals could squeeze into gaps in the data traffic that flows around the large optical-ring networks between cities. "Importantly, new traffic can be squeezed into the fibre at any location and added to any ‘lane’ of the fibre freeway even between existing lanes. Our system is far more flexible than alternative technologies," he said.

The technology would maximise existing infrastructure, allowing it to cope with the rising demand for internet, which is expected to increase by 1000 fold over the next decade.

"Rather than laying hundreds of new parallel optical fibres to boost network capacity, we can make more efficient use of the existing network by tweaking the way data is transmitted over long distances," Professor Lowery said.

"The NBN is effectively building a data road to every single house in Australia. We've found a way to make the data highways between cities and countries, far more efficient, with minimal extra investment" he added.

Dr Schröder said “Our approach is so flexible, network operators could adjust capacity to respond to increased demand, for example, from people during major sports event like the Olympic Games.”

The CUDOS research team has demonstrated that the method packs the data channels very close together, effectively allowing more lanes on the same super-highway.

"Previously, data was transmitted with gaps between the channels - this translates to wasted carrying capacity," Dr Du said.

"Because we are have made use of equipment that is already on the market, this technology could be translated to the consumer quite quickly."

Arthur Lowery, Ben Eggleton, Jochen Schroeder and Liang Du

From left: Arthur Lowery, Ben Eggleton, Jochen Schroeder and Liang Du

Paper Details

Flexible All-Optical OFDM using WSSs

Liang B. Du┬╣, Jochen Schröder2, Joel Carpenter2, Benjamin J. Eggleton2, Arthur J. Lowery┬╣;
1 Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS), Department of Electrical and Computer Systems Engineering, Monash University, Australia;
2 CUDOS, The School of Physics A28, The University of Sydney, Australia.

A LCOS WSS implements an optical inverse Fourier transform for 10-Tb/s OFDM signal generation and cyclic prefix insertion. After 857.4 km of dispersion uncompensated transmission, a second WSS implemented optically-banded digital subcarrier demultiplexing.