UNLOC Programme 2016-17 Research Review

UNLocking the capacity of Optical Communications

2016-17 Review

The UNLOC programme is about new approaches to unlocking the capacity of future information systems that go beyond the limits of current optical communications. It seeks to combine techniques from information theory, coding and modulation, nonlinear optics and digital signal processing to make possible breakthrough developments to ensure a robust communications infrastructure for the future.

Welcome to the 2016-17 UNLOC review.

This review is a summary of some of our milestone achievements over the year, as well as some more recent successes.

In 2016 we celebrated 150 years since the first trans-Atlantic telegraph cable and 50 years since Kao and Hockham’s first proposal of optical fibre as a universal communication transmission medium; a momentous year for the field of optical communications.

A high-capacity digital communications infrastructure, of which optical fibres are an essential part, underpins the internet and is essential to all aspects of the digital economy and everyday lives. I am proud of the work undertaken by UNLOC members, which will impact the development of next-generation optical communication networks.

Please get in touch for further information or to find out how we can work with you.

Prof Polina Bayvel, UNLOC Director

2016 RESEARCH HIGHLIGHTS 1.125 Tb/s data rate record

In February 2016, we set a new record for the fastest ever data rate for digital information.

UNLOC members from UCL Optical Networks Group (ONG) achieved a rate of 1.125 Tb/s as part of research on the capacity limits of optical transmission systems, designed to address the growing demand for fast data rates.

The UCL UNLOC team used their state-of-the-art test bed to design next generation core networking and communications systems able to handle data signals at rates in excess of 1 terabit per second (Tb/s). The rate they achieved is almost 40,000 greater than the 30 Mbit/s defined as “superfast” broadband in the EU. That’s fast enough to download every episode of Game of Thrones in HD within a second.

The study used techniques from information theory and digital signal processing to custom build an optical communications system with multiple transmitting channels and a single receiver.

Read more: bit.ly/1TbRecord

Ongoing collaborations with Mitsubishi Electric Research Laboratories (MERL)

MERL have generously pledged $100,000 towards the work of the Optical Networks Group at UCL. Prof Bayvel has developed a longstanding relationship with MERL, which stemmed from Dr David Millar joining MERL from UCL ONG. Our latest joint achievement (presented at OFC 2017) is a dual-carrier 1Tb/s transmission using a transceiver suitable for implementation in commercial systems. Realising these next generation communication systems is crucial if we are to outpace the growing demand for data.

Read more: bit.ly/UNLOC-MERL

Increasing capacity with a technique proposed in 1970s

UNLOC colleagues from Aston University and UCL confirmed experimentally that a laserbased technique first proposed in the 70s can be successfully applied in long distance fibre communications systems to significantly increase their capacity and reach.

The team used a technique called Optical Phase Conjugation (OPC) to effectively reduce the undesirable effect of nonlinearities in a very high-capacity transmission link achieving up to 60% increase in the distance which information could travel and still be successfully received.

Optical Phase Conjugation (OPC) undoes distortions in optical waves introduced by the medium in which they travel. It has been known for several decades but it had not previously been tested in optical communication systems with data rates on the order of Tb/s.

In this study, UNLOC researchers used a single OPC device in a 2,000 km fibre link to show for the first time, in systems with data rates from 800 Gb/s to 4Tb/s, that OPC can successfully deal with nonlinearities, improving signal quality and allowing information to travel much further.

Read more: bit.ly/UNLOC-OPC

Revolutionising Data Centre Design

In June 2016, members of UNLOC began working with Microsoft to design a new optical switch scaling to more than 1000 ports for future large data centres. A switch of this kind would allow for far higher data rates and shorter, more predictable delays between racks of servers in data centres as well as simplified management and lower cost for the data centre network.

Data centres are key to ensuring an efficient, low-delay, high-capacity cloud infrastructure, an infrastructure many of us rely on without thought every time we watch video-on-demand or do an online shop.

Most data centre networks are currently built using low port-count electrical switches, typically 32 to 48 ports. However, this requires many switches and transceivers representing a very large proportion of the cost of building a new data centre. The use of highly sensitive coherent receivers with passive optics could allow switches with much higher port counts.

Microsoft, one of the world’s largest data centre operators, hope this research will influence the design of their own data centres.

Read more: bit.ly/UNLOC-1000port

RECENT SUCCESSES Show of expertise in fibre nonlinearity Optics Express, an Optical Society of America (OSA) journal, published a special issue in February 2017 on “Nonlinearity mitigation for coherent transmission systems”. UNLOC researchers contributed to 9 papers, accounting for more than 50% of the issue as a whole.

Dr Lidia Galdino and colleagues from UCL’s Optical Networks Group showed how transmitter and receiver noise interacts with data in a nonlinear way. This is a new fundamental limiting factor in the capacity of optical communications and has huge impact on the design of next-generation systems.

Dr Mariia Sorokina and colleagues from Aston University have proposed a low complexity machine learning scheme that could help increase the throughput of fibre broadband.

The new tool is called the sparse identification method for optical systems, or SINO. SINO determines the minimum, optimum number of variables in the transmission system required for adaptive mitigation of effects (nonlinearities in fibre optic cable) that limit the throughput of standard optical fibre. The SINO method is significantly less complex than other similar compensation techniques. This bodes well for future commercial deployment.

Read more: bit.ly/UNLOC-OpEx

Awards

UNLOC members have received several distinguished awards: Prof Polina Bayvel - Commander of the Order of the British Empire and Fellow of The Royal Society Prof Seb Savory - Fellow of the OSA and Fellow of the IEEE Dr Dom Lavery - Royal Academy of Engineering Postdoctoral Fellowship Prof Sergei Turitsyn and Prof Andrew Ellis - 50th Anniversary Chair, Aston University

Get in touch Programme Director Prof Polina Bayvel UCL Optical Networks Group Tel: +44 (0)20 7679 7921

Programme Co-Director Prof Sergei Turitsyn Aston Institute for Photonic Technologies Tel: +44 (0)121 204 3538

Communications Officer Rachel Cronkshaw UCL Tel: +44 (0)20 3108 4406

Web: www.unloc.net Email: contact@unloc.net Twitter: @UNLOCprogramme