The aim of this fellowship is to develop disruptive approaches through theory and experiment to unlock the capacity of future information systems. To go beyond current optical fibre channel limits is arguably the greatest challenge faced by digital optical communications. To target it, the proposed research will combine techniques from information theory, coding, higher-dimensional modulation formats, digital signal processing, advanced photonic design, and machine learning to make possible breakthrough developments to ensure a robust communications infrastructure beyond tomorrow. Optical communications have to-date been able to fulfil the ever-growing data demand whilst simultaneously reducing cost and energy-per bit. However, optical communications have now exceeded the fundamental capacity of existing single-mode technology a trend leading to a rapid duplication of line systems which in time will translate in less affordable broadband access. To meet future demands with prospective cost and energy savings and avoid the impending exhaust of fibre capacity, this fellowship offers a scalable path towards parallelism in optical fibre communications resembling the advent of parallel computing using multiple cores to sustain Moore's law - once we were unable to double the number of transistors in a single-core microprocessor. The emergent technology of spatial division multiplexing (SDM) provides much wider conduits of information by offering additional means for transporting channels over one single fibre, using multi-mode and multi-core fibres. The fellow has shown that the internal structure of optical fibres can be optimised to support thousands of different spatial paths, each with full transmission capacity. And, critically, that there are principal launching conditions that allow for full transmission rate over each path with a small fraction of the equalisation cost assumed before. These discoveries offer the potential to foster a revolution in how optical fibre communications networks operate to meet the ever-increasing traffic demand with decreasing cost and energy consumption per bit, enabling ubiquitous and universal broadband access. This fellowship renewal envisages how to achieve chip-scale integration for multimode SDM transceivers packing intelligent optical beamforming powered by generalised machine learning and principled digital signal processing for highly spatially diverse fibre channels. Moreover, this fellowship renewal will initiate a new class of low crosstalk multi-mode fibres using elliptical cores and a new class of multimode optical fibre amplifiers with adaptive mode gain profile - opening fundamentally new theoretical and experimental possibilities up to now unexplored for SDM systems. These new developments will push multimode SDM technology far beyond that of the standard single-mode fibre infrastructure and bring it to an industry-ready development stage, unlocking decades of capacity growth in future optical networks with sustainable cost- and energy-per-bit.

Metal-organic frameworks (MOFs) are three-dimensional structures composed of inorganic nodes, connected by organic linkers. The ease at which different elements or functionalities can be incorporated into a plethora of nanoscopic architectures has led to the population of an enormous class of compounds. Over 60,000 crystalline structures have been reported, which can be 'tuned' to exhibit exceptional selectivity for pre-determined target guest molecules. Two products, from companies span out of Northwestern and Queen's University Belfast, have been commercialised, in the areas of toxic gas storage and fruit packaging. Furthermore, huge societal and economic benefits from their use in highly selective CO2 capture, drug delivery, chemical sensing, toxic gas separations and harmful waste storage applications have been proposed, though not delivered. This is partly due to the gap between the significant strides made in chemical synthesis, and a dearth of work on their physical properties. It is therefore highly surprising that even the most basic of all physical properties, the state of matter, represents one of the most under-researched areas in the MOF field. This proposal hence aims at addressing this bias towards the ordered, crystalline solid domain, which is vital given the research invested into the field and the potential benefits from the combination of the mechanical stability of the amorphous domain, with the chemical opportunities afforded by MOFs. The recent discovery of the glass-forming ability of the MOF family offers the tantalising prospect of accurately designing functional glasses by first tuning the chemical properties of the parent crystalline framework, prior to subsequent melting and liquid quenching. The transfer of functionality from crystal to glass in this manner will enable the next generation of a plethora of functional glasses to be produced. Such materials will lie at the forefront of efforts to move MOFs away from the current focus on the crystalline porous state. Two new classes of functional MOF-glasses will be produced in the course of the project; (i) porous MOF-glasses for separations and (ii) chiral MOF glasses for advanced optical applications. With respect to the former, the development of porous MOF-glasses or MOF-glass composite membranes for gas separations would prove a significant advancement in the field, given the current mixed matrix membranes suffer from chemical compatibility problems and a reduction in active component. In addition, reactions between MOFs in the liquid phase will be studied, and the structure and properties of the resultant multicomponent glasses produced investigated. The 'soft' nature of MOFs also leads to the structural collapse of some frameworks during the post-processing processes (e.g. sintering, ball-milling, pelletisation) used to convert nano-crystalline powders to industrially useable morphologies. The development of a variety of morphologies (i.e. thin films, beads, and self-supporting, binder-free membranes from microcrystalline powders is therefore absolutely essential for the field to move forwards to application. Concentrating on both fundamentally expanding our basic understanding of the field and at the same time bridging the gap between basic science and industrial relevance, this project is highly interdisciplinary in nature. The overarching aims of this proposal are thus to; (i) create new porous and chiral MOF-glasses (ii) create new composite materials for separation by combining crystalline MOFs and their glassy counterparts, (iii) produce a binary phase diagram for the reaction of two MOF liquids and analyse the products formed and (iv) cross-link unstable MOF spheres produced in previous work by the group, and extend the methodology to another MOF family.

I propose a new approach to supplying technologies for the last-mile global communication networks. High-speed data links are central to an ever-more integrated digital economy where, every day, more and more data is shared on our already over-stretched communications networks. A key challenge is the development of new high-bandwidth, secure communication networks, particularly through the internet. The online multimedia services we use on a daily basis are huge users of network bandwidth. With the number of multimedia users in the UK increasing on a monthly basis, the result is a huge drain on the available network bandwidth. Even in standard definition, watching our favourite TV show uses around 1GB of data per hour (and 3GB per hour for high definition). Beyond multimedia, as cloud-based storage and computing becoming the norm establishing high-bandwidth communication networks will be vital. Core backbone communication networks are regularly upgraded to deal with these demands, however the last-mile network, which takes our Internet services to homes and offices, is difficult and expensive to upgrade. This difficulty arises from the distributed nature of this portion of the network and solutions for cost effective, and sustainable, upgrades are required to be commercially deployed over the next 5-10 years. This project the aims to develop solutions to implementation of high-speed free-space last-mile networks. Using light beams carrying Orbital Angular Momentum, a single point-to-point link will increase the number of data carrying channels. Using orbital angular momentum in this way is an example of spatial multiplexing. These multiplexing techniques have the potential to offer multiplicative increases in data rates whilst simultaneously increasing the security of the link. A key deliverable will be the development of a last-mile building to building link within our new campus, for the development and testing of prototype novel multiplexing and de-multiplexing technology. Working with Industrial partners Intel and Corning, solutions will be developed in line with their market requirement, allowing near-term commercial uptake. These industry inspired challenges raise some questions about the fundamental nature of long distance propagation of spatial modes. Hence, along with overcoming the technical hurdles this project aims to investigate the effect of turbulence within the free-space propagation of spatially multiplexed beams. In the early stages of this project, studies into the optical aberrations, and modal cross coupling will be carried out in different environmental settings. This vital data will provide a base to design and develop passive, and active approaches to overcoming the limitations imposed by atmospheric turbulence. Further to these challenges, techniques to allow integration into current installed fibre networks will be developed. The proof-of-principle link will allow real life user testing, where standard internet services will be demonstrated over the link, aiming to providing a commercially viable last-mile link design as a key deliverable of the project.

The aim of this proposed research is to address the modelling, design, demonstration and potential applications of ultra-wide-band (UWB) optical fibre amplifiers based on the Raman effect, induced by high power laser pumping of specially designed optical fibre, for future applications in optical fibre communication networks, ranging from inter-data-centre connections to metro/regional networks. Despite massive advances in the capabilities of optical fibre communication systems over the past two decades, enabled by digital coherent technology, internet traffic growth remains well above 20% per annum, and is forecast to continue on a strong trajectory for the foreseeable future. Delivering a seamless optical amplifier of unprecedented bandwidth is now seen by operators and their network equipment suppliers as the most practical and cost-effective way to increase the traffic carrying capacity of the billions of km of glass fibre that has been deployed worldwide, by making use of the wide low-loss window. The programme targets two specific designs of all-Raman amplifier: (i) a node-located, discrete-only parallel, dual-stage design, and (ii) a hybrid distributed-discrete dual-stage design, making use of the intra-node transmission fibre as a gain medium for part of the spectrum. These innovative designs are enabled by recent increases in laser pump powers and novel nonlinear Raman gain fibres, and a growing, general acceptance of Raman technology by all network operators, ranging from relatively conservative incumbents, such as Verizon, to more adventurous technology giants, such as google. New, nonlinear, modelling tools will be developed to overcome and support the significant experimental design challenges in manufacturing and operating our proposed UWB amplifiers, which with 300nm bandwidth offer approaching 10x the bandwidth of standard Erbium-doped fibre amplifiers used in today's networks. Key optical amplifier characteristics such as gain, noise figure, uniformity and nonlinearity will be measured stand-alone. UWB optical fibre communication system capacity improvements and performance will be evaluated in representative models of target networks, informed by our project partners, and compared with extensive in-line and recirculating loop UWB laboratory-based tests.

Photovoltaic (PV) devices convert sunlight directly into electricity and form an increasingly important part of the global renewable energy landscape. Today's PVs are based on conventional semiconductors which are energy-intensive to produce and restricted to rigid flat plate designs. The next generation of PVs will be based on very thin films of semiconductors that can be processed from solution at low temperature, which opens the door to exceptionally low cost manufacturing processes and new application areas not available to today's rigid flat plate PVs, particularly in the areas of transportation and buildings integration. The emerging generation of thin film PVs also offer exceptional carbon dioxide mitigation potential because they are expected to return the energy used in their fabrication within weeks of installation. However, this potential can only be achieved if the electrode that allows light into these devices is low cost and flexible, and at present no electrode technology meets both the cost constraint and technical specifications needed. This proposal seeks to address this complex and inherently interdisciplinary challenge using three new and distinct approaches based on the use of nano-structured films of metal less than 100 metal atoms in thickness. The first approach focuses on the development of a low cost, large area method for the fabrication of metal film electrodes with a dense array of holes through which light can pass unhindered. The second approach seeks to determine design rules for a new type of 'light-catching' electrode that interacts strongly with the incoming light, trapping and concentrating it at the interface with the semiconductor layer inside the device responsible for converting the light into electricity. The final approach is based on combining ultra-thin metal films with ultra-thin films of transparent semiconductor materials to achieve double layer electrodes with exceptional properties resulting from spontaneous intermixing of the two thin solid films. The UK is a global leader in the development of next generation PVs with a growing number of companies now focused on bringing them to market, and so the outputs of the proposed programme of research has strong potential to directly increase the economic competitiveness of the UK in this young sector and would help to address the now time critical challenge of climate change due to global warming.