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 measurement and sensing, has been developed at the University of Southampton. In a paper titled “Multilevel Quantization of Optical Phase in a Novel Coherent Parametric Mixer Architecture,” which was published in Nature Photonics on Oct. 9, a team led by David Richardson at the university’s Optoelectronics Research Centre 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 Richardson, the new device allows an unprecedented level of control and flexibility in processing light using light — functionality required now that ultrahigh-speed optical signals can be found everywhere from communication links between microprocessor cores in next-generation supercomputers to the sub-sea fiber links spanning continents. “Today parametric mixers are routinely used for laser wavelength conversion, spectroscopy, interferometry and optical amplification,” said doctoral student Joseph Kakande. “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 fiber at more than 100 Gb/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 envision many as-yet-unknown deployment opportunities, given that controlling the phase of light also finds use in applications that range from enabling ultrasensitive interferometers in the hunt for gravitational waves to facilitating the probing of the inner workings of cells. The project is part of the European Union Framework 7 PHASORS project, completed earlier this year. For more information, visit: www.soton.ac.uk