New optical signal processing for power-hungry, high-speed networks

A new all-optical signal processing device to meet the demands of high capacity optical networks and with a wide range of applications including ultrafast optical measurements and sensing has been developed by researchers at the University of Southampton.

In a paper entitled: Multilevel quantization of optical phase in a novel coherent parametric mixer architecture, published in Nature Photonics this October, a team of researchers led by Professor David Richardson at the University of Southampton's Optoelectronics Research Centre (ORC), describes a simple and reconfigurable device created to automatically tune the phase property of ultrafast light signals. This phase quantization function is analogous to the way electronic circuits can adjust electrical signals to ensure their voltage matches the discrete set of values required for digital computing.

According to Professor Richardson at the ORC, this is a significant breakthrough because their new device allows an unprecedented level of control and flexibility in processing light using light, functionality required now that ultra-high speed optical signals can be found everywhere from  communication links between microprocessor cores in next generation supercomputers to the sub-sea fibre links spanning continents.

“Today parametric mixers are routinely used for laser wavelength conversion, spectroscopy, interferometry and optical amplification,” said Mr Joseph Kakande a PhD student at ORC who undertook most of the research “Conventional parametric mixers when operated in a phase sensitive fashion have for many decades been known to have a two-level response. We have now managed to achieve a multilevel phase response which means that we have demonstrated for the first time, a device that squeezes the classical characteristics of its input light to more than two phase levels.”

As an example, the team has already used the device to remove noise picked up by a signal in during transmission in optical fibre at over 100 Gbit/s. In principle, this can be done even faster, at speeds hundreds of times greater than could be done using electronics, and crucially, using less power. The researchers envisage many as yet unknown deployment opportunities, given that controlling the phase of light also finds use in applications spanning enabling ultrasensitive interferometers in the hunt for gravitational waves to facilitating the probing of the inner workings of cells.

Multi-level quantization of optical phase in a novel coherent parametric mixer architecture is available from our publications library online.

Published: 15 October 2011