Next-gen telco chip to speed up submarine links

Coherent system to overcome fibre bandwidth limits.

Researchers have designed a silicon chip that could replace trays of power-hungry electronics in next-generation optical telecommunications networks.

The chip aimed to improve coherent optical systems in development at Siemens, Alcatel-Lucent and AT&T, which transmitted more data within a given frequency range through previously unused properties of light.

Coherent systems transmitted multiple, simultaneous data streams using the phase and polarisation of an optical signal – similar to existing multiplexing techniques which used timeslots or varied colours of light.

Measuring a signal’s phase and polarisation typically involved complex calculations and trays of electronic equipment, University of Sydney physicist David Moss explained.

“Five to seven years ago, people would laugh at you for suggesting that bandwidth over fibre would not be enough,” Moss said. “We are running into that now.

“Certainly in the future, systems will use this [coherent] technology,” he said, describing it as “one of the holy grails of optical telecommunications”.

Moss and his team from Canada, Italy, the US and Hong Kong adapted the SPIDER (Spectral Phase Interferometry for Direct Electric-Field Reconstruction) pulse measurement technique, typically used in high-power laboratory environments, to telecommunications signals.

The team described integrating their SPIDER technique on a silicon chip in a report published in the Nature Photonics journal this week.

The development, they wrote, represented “a fundamental advance not only for applications to optical coherent telecommunications... but also for different areas such as computing microchips”.

It was based on prior work by team member Alessia Pasquazi from Canada’s Universite du Quebec.

“On-chip optical interconnects based on telecom phase-coding may be used in the next generation of microprocessors to improve their performance in terms of speed and power consumption,” the researchers reported.

“We believe this work represents a key milestone in achieving full characterisation of complex ultrafast optical waveforms on a chip."

Moss said the chip was 10,000 times more effective than electronic calculation methods and performed measurements far more quickly and precisely, allowing network engineers to detect and address issues like jitter.

He expected undersea links to be one of the first areas to receive “state of the art” coherent optical technology, where bottlenecks typically occurred.

US telecommunication networks would also benefit from the technology, he said, to handle traffic to and from the country’s large population.

The researchers’ commercialisation plans were unclear; Moss said the chip could initially be marketed as an out-of-the-box upgrade to existing fibre networks.

The technology's use to cut down power consumption could also be used for internet-wide systems. A consortium of universities, research institutions, telcos and hardware vendors had recently banded together under the Greentouch initiative in an attempt to reduce the internet's energy consumption by a factor of 1000 over ten years by redeveloping core servers and systems.