Coherent optical access networks

Currently optical access networks might advertise peak rates in the gigabits per second range, but the average and also minimum rate is significantly reduced by up to two orders of magnitude due to the time division multiplexing structure employed. In this PhD an alternative access network based on coherent passive optical networks will be researched, whereby the service can be guaranteed, since ultra-dense wavelength division multiplexing is employed in combination with digital signal processing and coherent detection.
A key aspect of the project is to significantly simplify the photonic technology employed in the coherent transceiver while minimising the impact on performance, for example utilising advanced digital signal processing to permit the use of low cost directly modulated lasers, or utilising polarisation block coding to minimise the number of required photodiodes for phase and polarisation diversity. The project will also examine the optimum trade-off between time and wavelength division multiplexing to minimize the cost while taking into account expected traffic patterns associated with future network services.
A key research challenge will be addressing the burst mode nature of the PON associated with the time division multiple access used. While this allows the optical layer to multiplex data, it creates significant challenges due to transients introduced, and this is of particular concern for coherent receivers which are sensitive to transient changes in phase, polarization and wavelength. It is expected that to address the physical models will need to be used to model the transients with the aim of pre-compensating digitally to mitigate their impact.
A key outcome of the PhD would be to simulate and hence design and experimentally evaluate a low cost coherent PON solution for multigigabit/s optical access networks. The aim is to use the existing installed fibre infrastructure but increase the data rates by an order of magnitude moving towards peak data rates of hundreds of gigabits per second with an aggregate capacity of terabits per second. Ultimately this project will shape the future direction of access networks including fibre to the home. The project will include numerical simulation, analytical approaches and experimental work albeit the balance between this would be tailored according to the aspirations of the individual student.

The impact of the CDT in Connected Electronic and Photonic Systems is expected to be wide ranging and include both scientific research and industry outcomes. In terms of academia, it is envisaged that there will be a growing range of research activity in this converged field in coming years, and so the research students should not only have opportunities to continue their work as research fellows, but also to increasingly find posts as academics and indeed in policy advice and consulting.

The main area of impact, however, is expected to be industrial manufacturing and service industries. Relevant industries will include those involved in all areas of Information and Communication Technologies (ICT), together with printing, consumer electronics, construction, infrastructure, defence, energy, engineering, security, medicine and indeed systems companies providing information systems, for example for the financial, retail and medical sectors. Such industries will be at the heart of the digital economy, energy, healthcare, security and manufacturing fields. These industries have huge markets, for example the global consumer electronics market is expected to reach $2.97 trillion in 2020. The photonics sector itself represents a huge enterprise. The global photonics market was $510B in 2013 and is expected to grow to $766 billion in 2020. The UK has the fifth largest manufacturing base in electronics in the world, with annual turnover of £78 billion and employing 800,000 people (TechUK 2016). The UK photonics industry is also world leading with annual turnover of over £10.5 billion, employing 70,000 people and showing sustained growth of 6% to 8% per year over the last three decades (Hansard, 25 January 2017 Col. 122WH). As well as involving large companies, such as Airbus, Leonardo and ARM, there are over 10,000 UK SMEs in the electronics and photonics manufacturing sector, according to Innovate UK. Evidence of the entrepreneurial culture that exists and the potential for benefit to the UK economy from establishing the CDT includes the founding of companies such as Smart Holograms, PervasID, Light Blue Optics, Zinwave, Eight19 and Photon Design by staff and our former PhD students. Indeed, over 20 companies have been spun out in the last 10 years from the groups proposing this CDT.

The success of these industries has depended upon the availability of highly skilled researchers to drive innovation and competitive edge. 70% of survey respondents in the Hennik Annual Manufacturing Report 2017 reported difficulty in recruiting suitably skilled workers. Contributing to meeting this acute need will be the primary impact of the CEPS CDT.

Centre research activities will contribute very strongly to research impact in the ICT area (Internet of Things (IoT), data centre interconnects, next generation access technologies, 5G+ network backhaul, converged photonic/electronic integration, quantum information processing etc), underpinning the Information and Communications Technologies (ICT) and Digital Economy themes and contributing strongly to the themes of Energy (low energy lighting, low energy large area photonic/electronics for e-posters and window shading, photovoltaics, energy efficient displays), Manufacturing the Future (integrated photonic and electronic circuits, smart materials processing with photonics, embedded intelligence and interconnects for Industry 4.0), Quantum Technologies (device and systems integration for quantum communications and information processing) Healthcare Technologies (optical coherence tomography, discrete and real time biosensing, personalised healthcare), Global Uncertainties and Living with Environmental Change (resilient converged communications, advanced sensing systems incorporating electronics with photonics).