Photonics expertise becomes more valuable as demand for bandwidth grows

4 min read

Demand for data bandwidth – not only driven by such things as YouTube and the BBC's iPlayer, but also by the huge amount of data being accessed from mobile devices – is doubling every two years. And as our appetite for data grows, so too does the strain on the internet and its components.

The time is coming when, if nothing is done, the internet will grind to a halt – maybe within the next 10 years. Looking to develop technology which will avoid this, the University of Southampton and the University of Essex are joining with BBC Research and Development, Oclaro and Fianium in the 'Photonics HyperHighway' project. The team behind this six year project, which is receiving £7.2million of funding from the Environmental and Physical Sciences Research Council (EPSRC), believes it could increase bandwidth by one hundred fold. According to minister for Universities and Science, David Willetts: "The Photonics HyperHighway project has the potential to truly revolutionise the internet, making it much faster and more energy efficient. The project is also a shining example of the UK's world leading role in this area of research and I look forward to the exciting breakthroughs it will bring." Leading the project is Professor David Payne, pictured, director of the Optoelectronics Research Centre at Southampton. He said: "Downloading a fully composite video signal of Blu-Ray quality requires a bandwidth of 24Mbit/s. Most people in the UK probably have 4Mbit/s. We have looked at this, as have a number of labs around the world, and have concluded something has to break." The Photonics HyperHighway project aims to head off this breakage by looking at all aspects of the internet and aiming to improve their performance. Prof Payne said: "What we in the research community have been doing is to enhance existing bandwidth by using coding techniques borrowed from the mobile phone industry. But a simple projection shows we're at the end of where current fibre technology can go; we can't get any more bandwidth." There are options, of course. "The number of optical fibres could be doubled," he continued. "But that's unpalatable for some and it's an expensive way forward. So the HyperHighway project says there's another way forward. "We're essentially still at internet 1.0, while the mobile world is at 3G and 4G. We need to be thinking about internet 2.0 – and it will look very different." Partly, the project is intended to underline the UK's photonics heritage. "The UK pioneered the early days of fibre optics," Prof Payne claimed, "even when some said it wouldn't work." Amongst Southampton's achievements was the lowest loss fibre technology outside of Bell Labs and Corning. "In the early 1980s, we were developing special fibres with embedded functions, such as optical amplifiers." The work led to the development of wavelength division multiplexing, with optical amplifiers allowing the various wavelengths to be transported and amplified without being mixed. So what does the project intend to address? "The first place to start is the fibre itself," said Prof Payne. "We could use silica for future fibres, but what could we do to extend the bandwidth it can sustain? We need to broaden the range over which you can get communication and we also need better optical amplifiers. Who better to do this than Southampton?" The project will provide some serious challenges, particularly from the materials perspective. "We will have to go right back to the basic physics and ask what can be done," Prof Payne noted. "Another bottleneck is the routers and nodes on the web. They're electronic and we don't know how to put 'smarts' in optics and that has to be resolved. I'm not saying we could build an optical computer, but there are solutions which can use optical switching and which can still maintain control over factors such as quality of service." Attention will be focused on optical fibres. "One approach might be to have a single fibre with multiple cores. It sounds simple, but there are issues; how do you splice them, for instance? Will you get crosstalk and how can you build an amplifier for 10 cores with a pump laser which doesn't interact?" Today's systems are based on 1550nm light, but moving to longer wavelengths will reduce losses. "The problem with 1550nm," said Prof Payne, "is that it is as far as you can get into the infrared before losses start to increase because of absorption. That's material related. If we can find another material, we can change that." Several materials are being investigated, including fluoroglasses and other composites. The problem is that some of these materials are water soluble – not ideal for the application. "While some are 'tweaks' of silica, others are radically different," Prof Payne claimed. "But the first stage is to explore the options." Another area of work will investigate how TCP/IP can work more effectively with optics. "TCP/IP is not ideal for optics as they don't switch easily," said Prof Payne. "But, as we intend to use packet switching, we should be exploring with people in the electronic domain how flexible they could be to let optics move further into the network. For example, optics is good at steering beams to different ports, depending upon their wavelength." The fact that Photonics HyperHighway is a six year project means it needs big targets – 'we are being iconoclastic', Prof Payne believes. "Can we find different materials – metamaterials, for example – that have switching and routing functions and maybe some intelligence? These will help to develop the internet 2.0 concept." There might be big targets but these should not be 'crazy', he believes. "We understand that it is no good for academics to come up with 'crazy' technology. We are conscious that what we develop is adoptable in the real world." But Southampton won't be working alone. While it develops the technology, the Essex University team, led by Professor Dimitra Simeonidou, will be developing ideas of how networks need to develop. "It is a very ambitious programme," added Professor Simeonidou. "We are designing a hyper highway which is going to meet future internet demand." Prof Payne added: "It's all very well for engineers to develop next generation technology, but we need to understand where content providers are going. Essex has good links with the BBC, which is driving technology." Oclaro, formed after a merger between Bookham and Avanex, is a leading provider of optical and laser components and solutions for a range of applications. Fianium, meanwhile, is focused on developing ultrafast high power laser systems, covering wavelengths of up to 2500nm. In particular, it is focusing on femtosecond lasers and has recently launched the brightest white light lasers yet developed. "Looking back," Prof Payne concluded, "it took 10 years for optical amps to get from the lab to volume. That was considered fast. Given the bandwidth issues we anticipate from 2020 onwards, it's timely we start work now."