Researchers Claim Data Transmission Record

CARDIFF, England, Sept. 10 -- Researchers at the University of Essex are exceeding their earlier world record for the amount of computer data sent over a single multimode optical fiber.

The results achieved by the team from the Department of Electronic Systems Engineering are the equivalent of more than 15 million phone calls or internet connections being made simultaneously. Such large capacity could revolutionize internet download times for many households and local businesses.
While their results don’t compare with data transmission using the latest-generation single-mode fiber
-- the type now used for global communication -- they are important because many buildings and local area networks still use multimode fiber.

The record-breaking results came at the end of a three-year project, conducted by Ph.D. student Pandelis Kourtessis, funded by the Engineering and Physical Sciences Research Council (EPSRC) and carried out in partnership with researchers at the University of Bristol.

The Essex experiements demonstrate that far greater capacity could be obtained from legacy-installed multimode fiber networks.

Stuart Walker, Ph.D., who headed the Essex project, said: "It was a last-minute brainwave to give this a try. It's a huge amount of data to transmit, and it proves that humble multimode fiber, the Cinderella-cousin of single-mode fiber, can talk the same language.

"This is a research lab experiment, but there is worldwide commercial interest in getting maximum capacity from the legacy installed multimode fiber base."

The experiments were carried out using multimode fiber borrowed from one of the university's teaching laboratories. The Essex team initially transmitted 404 Gigabits (that’s 404 billion, or 404 followed by 9 zeroes) of data over 40 wavelengths (or colors) of light over a single 3-km-long standard 50-micron core diameter multimode fiber, comparable to the width of a human hair. The data was transmitted without any errors.

Subsequently, it showed how the equivalent of 200 X 5.1 Gbit/s channels could be tranmsitted through 3 km of legacy 50 micron core graded index multimode fiber, Walker said.

"This is the equivalent of 1.02 Tb/s. We then showed how, using a very narrowband filter (6.25 GHz) from the American company Essex Corp., 16 X 40 X 2.55 Gbit/s = 1.6 Tb/s could be sent over 3 km."

Recently, Walker said, the Essex team showed how the 1.02 TB/s multimode link could, in principle, have its capacity doubled to 2.02 Tb/s over 3 km using circular polarisation multiplexing.

"This work is still in progress and is not perfect yet," he added.

Some early results are being reported at the European Conference on Optical Communication in Copenhagen this week, he said. The team is now attempting to deploy both linear and circular polarisation multiplexing to bring the throughput up to 4.04 Tb/s over 3 km, but Walker said "There is a long way to go on this."

He said Fujitsu Networks Corp., through its principal scientist Mike Parker, have been a consistent supporter of the work, along with EPSRC. The team also had assistance from Bookham Technologies.

For more information, visit: http://www.essex.ac.uk/ese/department.htm; e-mail: Stuart Walker, stuwal@essex.ac.uk