UCL Engineering


Smashing the (fibre) glass ceiling

Breaking the world record for data transmission via optical fibre glass.

Fibre optical abstract image

14 February 2020

Optical networks underpin the global digital communications infrastructure, and their development has stimulated the global growth in demand for data, raising fundamental questions on the ultimate capacity of the optical fibre channel.

The UNLOC Programme (UNLocking the Capacity of Optical Communications) was funded by the Engineering and Physical Sciences Council (EPSRC) with a vision to understand, quantify and maximise the capacity of optical fibres.

The optical fibre channel is unusual – and the barrier to increasing capacity is set by the nonlinear physical properties of the silica glass fibre – its refractive index varies with the optical signal intensity.

The goal of UNLOC’s research was to understand the capacity of such a channel, solve the issue of nonlinearity and break the transmission barriers.

The UNLOC research resulted in numerous firsts in how to generate, transmit, detect and process optical data.

Research showed it was possible, through a combination of advanced digital signal processing and nonlinear optics, to mitigate nonlinear distortions and to increase the transmission capacity by a factor of 100, doubling of transmission distances and achieving record transmission capacities over 120 Tbit/s in a single fibre.

To go beyond this, it became clear that we must use much more of the available 50 THz optical fibre bandwidth. The next step is to develop new sources, receivers and amplifiers to reach this goal.

The UNLOC Programme finished in March 2018 but achieved tremendous impact which will continue under the new EPSRC funded multi-disciplinary TRANSNET Programme, focusing on translating the capacity gains achieved in point-to-point systems to future optical networks.

Led by the Optical Networks Group (UCL), in collaboration with Aston and Cambridge universities, and leading industry partners, the mission is to transform optical networks for the next-generation cloud infrastructure through building intelligence, agility and speed into the digital information infrastructure.