The properties of light are already exploited in communications, the Internet of Things, big data, manufacturing, biomedical applications, sensing and imaging, and are behind many of the inventions that we take for granted today. Nevertheless, there is still a plethora of emerging applications with the potential to effect positive transformations to our future societies and economies. UK researchers develop cutting-edge technologies that will make these applications a reality. The characteristics of these technologies already surpass the operating wavelength range and electronic bandwidth of our existing measurement equipment (as well as other facilities in the UK), which currently forms a stumbling block to demonstrating capability, and eventually generating impact. Several important developments, relating for example, to integrated photonic technologies capable of operating at extremely high speeds or the invention of new types of optical fibres and amplifiers that are capable of breaking the traditional constraints of conventional silica glass technology, necessitate the use of ever more sophisticated equipment to evaluate the full extent of their capabilities. This project aims at establishing an open experimental facility for the UK research community that will enable its users to experiment over a wide range of wavelengths, and generate, detect and analyse signals at unprecedented speeds. The new facility will enable the characterisation of signals in time and will offer a detailed analysis of their frequency components. Coherent detection will be possible, thereby offering information on both the amplitude and phase characteristics of the signals. This unique capability will enable its users to devise and execute a range of novel experiments. For example, it will be possible to experiment using signals, such as those that will be adopted in the communication networks of the future. It will make it possible to reveal the characteristics of novel devices and components to an extent that has previously not been possible. It will also be possible to analyse the response of experimental systems in unprecedented detail. The facility will benefit from being situated at the University of Southampton, which has established strong experimental capabilities in areas, such as photonics, communications and the life sciences. Research at the extended cleanroom complex of Southampton's Zepler Institute, a unique facility in UK academia, will benefit from the availability of this facility, which will enable fabrication and advanced applications research to be intimately connected. Furthermore, this new facility will be attached to EPSRC's National Dark Fibre Facility - this is the UK National Research Facility for fibre network research, offering access and control over the optical layer of a dedicated communications network for research-only purposes. The two together will create an experimental environment for communications research that is unique internationally.

The geomagnetic field varies on time scales of milliseconds to billions of years, and has sources both inside the Earth, from the dynamo generating the main field in the highly conducting liquid iron core, and outside the Earth, from currents flowing above us in the ionosphere and magnetosphere, reflecting the interaction of the solar wind with our planet. In general, rapid variations (less than one year period) originate outside the Earth, while longer period variations come from inside. Separating signals from one to ten years is a challenge, but also has the potential to tell us much about Earth structure and processes. The most rapid variations generally identified as being of internal origin are so-called "geomagnetic jerks" - rapid changes in the rate of change of the magnetic field. Their structure and evolution can tell us not only about rapid changes in Earth's fluid core (such as waves and upwelling of core fluid) but also about the solid mantle in between. This rocky region is not as electrically conducting as the iron core, but it could still conduct weakly. A strong constraint on this property has recently been provided by another geophysical measurement, the rate of Earth rotation. We have found that sharp changes in the field are matched by almost contemporaneous sharp changes in the rate of Earth rotation. This both gives as clues as to what causes the events, but also strongly restricts the conductivity of the mantle - if this were higher, then the magnetic signal would lag the rotational signal as it would take time for the field to diffuse from its origin at the core-mantle boundary through the solid Earth to be observed at the surface. Mantle conductivity is also constrained by measurements of the induced magnetic field from varying external fields, so-called geomagnetic depth sounding. The combination of this constraint from above the Earth, and the new constraint from the deep mantle, will be used to give a detailed profile of conductivity as a function of depth, which in turn constrains the composition and mineral state of the solid Earth. For example, if a phase change of silicate rock were predicted which gives a sharp rise in conductivity, this phase change could be excluded by the geomagnetic data. The bulk of the work in this study is detailed analysis of both geomagnetic and Earth rotation data to tease out more information as to the signals they contain. A six-year oscillation has been confirmed in both measurements, but more rapid variations are even harder to distinguish, as they overlap with other sources: for the magnetic field, from external current systems, and for Earth rotation from angular momentum exchange with the atmosphere. For example, variations in short period (atmospheric) variations in Earth rotation have been shown to have a strong link to the ENSO climatic signal. A successful outcome of the project will rely on successful separation of the signals. We will construct detailed models of the magnetic field variation in space and time to investigate what is causing these changes. Recently, quantum mechanical calculations of the physical state of materials of the Earth's deep interior have revised our assumed value for the electrical and linked thermal conductivity of the core. These new values have changed our understanding of how the core works - we now believe that instead of full vigorous convection, it is highly likely that there is a stably stratified layer of fluid at the top of the core. This layer will support waves and instabilities rather than large scale convection, as is seen for our atmosphere and oceans, similarly stably stratified, rapidly rotating fluids. A recent simple model of these waves can explain the details of the variation of the dipole field in the Earth, and our preliminary results suggest that they may also explain the geomagnetic jerks. Thus our work should constrain both the structure of Earth's mantle, and the dynamics of its core.

Climate change is threatening two key ecosystem services provided by the ocean for humankind: food and storage of atmospheric carbon. The polar regions are major influences on both but are also experiencing the most dramatic and rapid changes. A better understanding of the factors affecting how nutrients are supplied and biologically processed in the ocean is needed to assess the future risk to quantify the dependence of the Earth system, and humanity, on this essential global function that supports global productivity and fisheries. Key nutrients, such as nitrogen (N) and phosphorus (P), are not evenly distributed across the global ocean but are in excess in the polar regions from where they are exported to lower latitudes by ocean circulation. Living matter is produced through combining N, P and carbon (C) (and other minor elements) in a ratio that is more or less the same in most regions of the global ocean. However, the ratios found in the polar regions are substantially different. This is because, firstly, polar nutrients come from a diversity of sources (glaciers, sea-ice, rivers and other seas). Secondly, the polar ecosystem processes these nutrients and carbon in distinct ways. This results in i) a nutrient surplus, which is exported from the polar oceans and supports productivity globally, and ii) the transport of carbon from the atmosphere into deep waters distant from the atmosphere. The pressing issue is that rapid climatic change at the poles is changing both the supply of nutrients and the processing capacity of their ecosystems. This threatens not only the marine food stocks on which humanity depends but also the biological drawdown of C in the oceans, a critical regulator of global climate. Our ability to fully characterise and predict this threat is limited by inadequate representation of polar biogeochemical and ecosystem processes in Earth System Models (ESMs). BIOPOLE represents and links together many of the major environmental research institutes in the UK, who will work with national and international partners to address this problem. We propose an ambitious combination of focussed observations, novel analyses and computer simulations to radically improve our ability to measure, understand and predict how nutrient supply and C storage in the polar regions will be affected by climate change. BIOPOLE will further identify and quantify the wider global impacts to ocean productivity and fisheries. We will sample and collect data at both poles to take a full Earth system perspective of this problem. The latest experimental and observational techniques will delineate C and nutrient processing by the unique polar communities. It will include the use of novel autonomous technologies to collect data over longer periods and greater areas than can be achieved by ships alone. Global modelling will be informed by the new understanding generated and used alongside other modelling approaches to better quantify the role that polar oceans play in sustaining global oceanic primary productivity and fish stocks, and to predict future trends. Climate change is proceeding faster at the poles than any other region, resulting in sea-ice loss and glacial melting. There is a clear urgency in understanding the full biogeochemical and ecosystem level implications of these changes for the polar regions themselves and for the wider Earth system. As ice retreats, the fragile and globally significant ecosystems that are exposed require international protection, which depends on building a strong body of scientific evidence through co-ordinated polar science. Direct outputs from the ocean resulting from ocean productivity have been valued at $6.9trn, while that of the capacity of the oceans to absorb C is $4.3trn. The uncertainty in how climate change will impact these roles remains large, requiring both scientific and economic evaluation, and presenting a pressing challenge for both science and society.

The prediction and analysis of sudden changes in complex systems and models (called tipping) are a current topic in science and an urgent problem for society. A few hotly debated examples are the possible collapse of the Gulf Stream, the sudden loss of vegetation in nutrient-polluted lakes, or the change between the vegetated and desert state in dry regions. While these cases of tipping are well understood in idealised mathematical models, their analysis is restricted in field observations, laboratory experiments and complex model simulations by the impossibility to systematically explore dynamically unstable phenomena. For many complex systems the notion of equilibrium is only defined in a statistical mechanics sense as an emerging phenomenon, which, by its definition, must be stable. The proposed research will develop general mathematical methods that will remove these restrictions: they will enable experimenters and modellers to discover and track unstable phenomena in laboratory experiments and complex model simulations, or, more generally, in any situation where one can provide input into the system depending on its output in real time. Two features distinguish the systems under study from the idealised models. * (Limited input only) One has input into the system but may not be able to set the entire internal state at will. * (Variability) The experiment or model run is repeatable, but the system has internal variability such that outputs are affected by randomness or disturbances. Several areas will serve as testbeds and springboards to the wider scientific community: individual-based models in ecology, epidemiology and social science, vibration tests in engineering, models of climate subsystems, and abstract spatially extended systems (such as used for neuron population models).

Most electrical equipment requires a power supply which usually incorporates a magnetic transformer to provide safety isolation and to step up or step down the input voltage. Piezoelectric transformers (PTs) offer an exciting alternative to conventional transformers particularly in applications requiring high power density, low electromagnetic interference and high temperature operation. Their widespread adoption is hindered, however, by the need for power supply designers to possess knowledge and training in both materials science and power electronics, combined expertise that is rarely found in industry or even academia. This lacking knowledge base represents a real impediment for power supply manufacturers who may wish to adopt PT technology and consequently PTs have only seen marginal market penetration. The project addresses these issues by producing a multi-physics design framework which provides abstraction from the fundamental science and therefore allows the design engineer to focus on the overall system design. The framework converts a high-level power supply specification into a PT power supply solution through a series of circuit and materials based transformations. An optimisation process (using evolutionary computing and finite element analysis) produces a fully characterised final design. The output of this process includes a circuit design and a "recipe" for the piezoelectric transformer, including materials and construction details presented in a format suitable for manufacture. The framework will be encapsulated in a user-friendly software design tool and validated against real-world power supply applications suggested by the project's industrial partners thereby ensuring the relevance of the research. The research, which will transcend the traditional barriers between electrical engineering and materials science, has an investigatory team with expertise in both areas. As well as developing a framework, the research will develop novel piezoelectric materials particularly suited to high temperature operation, finding promise in a number of application areas including aerospace, oil/gas exploration, electric vehicles and for remote monitoring in harsh environments. Additionally, the need for environmentally damaging lead-based PTs will be diminished through the development of new materials which comply with Restriction on Hazardous Substances 2016. The research programme will culminate in an open workshop where industry and academic researchers can learn about PT power supplies and evaluate the design tool for themselves. To ensure that the research remains industrially relevant we have partnered with several leading companies who will provide expertise and commercial drive and in return they will receive proof-of-concept power supplies ready for commercialisation.