This proposal seeks funding to create a Centre for Doctoral Training (CDT) in Connected Electronic and Photonic Systems (CEPS). Photonics has moved from a niche industry to being embedded in the majority of deployed systems, ranging from sensing, biophotonics and advanced manufacturing, through communications from the chip-to-chip to transcontinental scale, to display technologies, bringing higher resolution, lower power operation and enabling new ways of human-machine interaction. These advances have set the scene for a major change in commercialisation activity where electronics photonics and wireless converge in a wide range of information, sensing, communications, manufacturing and personal healthcare systems. Currently manufactured systems are realised by combining separately developed photonics, electronic and wireless components. This approach is labour intensive and requires many electrical interconnects as well as optical alignment on the micron scale. Devices are optimised separately and then brought together to meet systems specifications. Such an approach, although it has delivered remarkable results, not least the communications systems upon which the internet depends, limits the benefits that could come from systems-led design and the development of technologies for seamless integration of electronic photonics and wireless systems. To realise such connected systems requires researchers who have not only deep understanding of their specialist area, but also an excellent understanding across the fields of electronic photonics and wireless hardware and software. This proposal seeks to meet this important need, building upon the uniqueness and extent of the UCL and Cambridge research, where research activities are already focussing on higher levels of electronic, photonic and wireless integration; the convergence of wireless and optical communication systems; combined quantum and classical communication systems; the application of THz and optical low-latency connections in data centres; techniques for the low-cost roll-out of optical fibre to replace the copper network; the substitution of many conventional lighting products with photonic light sources and extensive application of photonics in medical diagnostics and personalised medicine. Many of these activities will increasingly rely on more advanced systems integration, and so the proposed CDT includes experts in electronic circuits, wireless systems and software. By drawing these complementary activities together, and building upon initial work towards this goal carried out within our previously funded CDT in Integrated Photonic and Electronic Systems, it is proposed to develop an advanced training programme to equip the next generation of very high calibre doctoral students with the required technical expertise, responsible innovation (RI), commercial and business skills to enable the £90 billion annual turnover UK electronics and photonics industry to create the closely integrated systems of the future. The CEPS CDT will provide a wide range of methods for learning for research students, well beyond that conventionally available, so that they can gain the required skills. In addition to conventional lectures and seminars, for example, there will be bespoke experimental coursework activities, reading clubs, roadmapping activities, responsible innovation (RI) studies, secondments to companies and other research laboratories and business planning courses. Connecting electronic and photonic systems is likely to expand the range of applications into which these technologies are deployed in other key sectors of the economy, such as industrial manufacturing, consumer electronics, data processing, defence, energy, engineering, security and medicine. As a result, a key feature of the CDT will be a developed awareness in its student cohorts of the breadth of opportunity available and the confidence that they can make strong impact thereon.

Our tangible cultural heritage, both historic and contemporary, is made from a plethora of complex multilayer materials. What we see is often only the surface and form of an object. Hidden below are the materials and evidence of the processes by which the objects were originally created. By using state of the art imaging / spectroscopy systems which can map the composition and reveal the stages of their creation, we gain an understanding about the meaning and significance, both in their original context and our present day. This is at the heart of the disciplines of technical art history, archaeology and material culture studies. It also informs collections care, access policies and conservation of cultural heritage. Infrared imaging and spectroscopy is particularly well suited to looking below the surface, as the scattering which normally occurs with visible light is usually much less. Thus the infrared penetrates further into the object. Depending on the material and its structure the infrared light will be absorbed or reflected. This can either be directly imaged or modulated (Fourier Transform Spectroscopy) to acquire spectroscopic information indicating the chemical composition. Most techniques employed at present within the field of cultural heritage can only make spot measurements; to map large areas would take hours to days to acquire the data and therefore is not usually viable or suitable for in-situ measurements. Other techniques require samples to be taken and are therefore invasive. We aim to explore state of the art IR imaging strategies that will be "fit for the job". This implies wide bandwidth, full field and fast techniques coupled with signal processing/ photonics methods to analyse, visualise and manipulate large multivariate data sets. By exploiting state-of-the-art laser sources developed at Heriot-Watt and providing massively tunable infrared light, we will explore and develop several complementary strategies for 4-dimensional imaging (3 x spatial, 1 x wavelength). Compressive sensing illumination techniques and machine-learning based data processing will allow us to image rapidly and efficiently while also extracting the maximum value from our datasets by automatically classifying surface and sub-surface features. In this way we expect to produce outcomes of shared value for both the ICT and Technical Art History researchers in our team. Contextual information from art history will inform the photonic design and computational anaylsis strategies we deploy, while powerful ICT-led techniques will provide the Technical Art History community with new technical capabilities that reveal previously hidden structure and history. The significance to the public of our cultural heritage has motivated us to integrate outreach activity from the start, in particular a dynamic website using 4D data to allow an interactive tool for exploring the chosen case studies, reflecting the People at the Heart of ICT priority. The project includes industrial partners who will contribute resources and expertise in mid-IR lasers (Chromacity Ltd.) and mid-IR cameras (Thales Optronics Ltd.). Our partners have committed substantial in-kind support in the form of access to their technology and contributions of staff time. Furthermore, their engagement ensures that activities within the project, and the outcomes these generate, can be rapidly evaluated for adjacent commercial opportunities. EPSRC priorities are reflected in the project's structure. Cross-Disciplinarity is embedded as collaborations within the ICT community (Photonics & AI Technologies researchers) and with researchers from the AHRC-funded Cultural Heritage community. Co-Creation is essential: only by combining the distinct technical, contextual and material resources of each research group in our team will the project succeed in delivering new capabilities for IR imaging and analysis and new insights into culturally important objects of shared value.

This proposal aims to transition today's highest precision laser technology -- optical frequency combs -- from the lab to the factory, establishing the technique of dual-comb distance metrology as an enabling technology for manufacturing the next generation of precision-engineered products, whose functionality relies on micro-/ nanoscale accuracy. Optical techniques form the basis of critical industrial distance metrology, but face compromises between accuracy, precision and dynamic range. Time-of-flight methods give mm accuracy over an extended range, while interferometric trackers achieve nm precision but with no absolute positional accuracy. By developing novel dual-comb metrology techniques, this project will bridge the gap between precision and extended-range accuracy, providing traceable nm precision, with almost unlimited extended-range operation. For manufacturing industry, comb metrology therefore addresses the important problem of how to verifiably fabricate macro-scale objects with nano-/micro-precision. Building on Heriot-Watt's frequency-comb expertise, we will develop Ti:sapphire and Er:fibre dual combs, with the aim of demonstrating nm-precision controlled-environment metrology using Ti:sapphire, and micron-precision free-space ranging using eye-safe Er:fibre. Besides their novel applications in precision metrology, by implementing new efficient and compact diode-pumping schemes our research will extend laser comb technology in a way that makes these systems suitable for deployment in a wide range of environments outside the research lab, for example as modules in a precision quantum navigation system. Our project integrates key academic and industrial partners who will contribute resources and expertise in lasers (Chromacity), precision micro-optics (Powerphotonic), industrial metrology and manufacturing (Renishaw), ultra-precision metrology (EPSRC Centre for Innovative Manufacturing in Ultra Precision and CDT in Ultra Precision) and applications in large optics for astronomy (STFC UK Astronomy Technology Centre). The commitment of our partners is evidenced by >£300K of support, including £145K of cash which will be used primarily to support two EPSRC EngD and PhD students recruited to the project. The project aligns closely with the EPSRC's Manufacturing the Future challenge theme and the ICT Photonics for Future Systems priority, as well as the EPSRC's training agenda, by engaging EngD and PhD researchers from the CDT in Applied Photonics and the CDT in Ultra Precision. More generally, the project will support the UK's high-precision manufacturing and metrology communities, with potential academic and industrial benefits. By the end of the project we expect to have demonstrated and evaluated dual-comb distance metrology in a variety of practical manufacturing contexts (machine calibration, in-process control, finished-product inspection), and to be in a position to translate the technology into our industrial and academic partners.

Multi-photon imaging is a ubiquitous tool in life sciences research, where pulsed tuneable lasers are required for precision microscopy. The majority of multi-photon imaging research employs two-photon fluorescent techniques, however three-photon fluorescence is emerging as a powerful instrument for deep-tissue (> 1mm) imaging as it offers reduced tissue scattering and enables access to a wide variety of fluorescent dyes and proteins. Non-destructive and non-invasive high-resolution imaging of cells through surrounding tissue and bone would be groundbreaking for research into areas including regenerative medicine and leukemia. The ideal three-photon excitation source is a low repetition frequency, high-energy femtosecond laser tuneable in the near-infrared with low average power to avoid tissue heating. The laser industry is focused on the two-photon imaging market, serviced by well-proven ~100MHz fixed wavelength and tunable sources. Three-photon excitation systems based on optical parametric amplifiers (OPAs) are available from select manufacturers, however these are highly inefficient and are prohibitively expensive for the majority of research facilities. A collaboration between an industrial laser manufacturer (Chromacity, UK) and STFC-funded academic research in photonics (McCracken, Heriot-Watt University), this project will demonstrate prototype cost-efficient lasers for three-photon microscopy, addressing this customer-driven demand by exploring two novel laser architectures to realize few-MHz optical parametric oscillators (OPOs), pumped by Chromacity's robust fiber laser technology. We will combine patented HWU IP in the generation of few-MHz high-energy OPO pulses with know-how in the construction of dispersion- controlled compact cavities to develop a commercial alternative to the dominant market offering. Working directly with early-adopters (Packer, Oxford; Lo Celso, Imperial; Williams, Edinburgh) and industrial beneficiaries (Scientifica), we will evaluate our OPO and develop it to a level where it can be brought to market in a compressed timeframe.

This project is a joint proposal between researchers in Photonics (Reid, Heriot-Watt University) and Robotics (Ramamoorthy, University of Edinburgh). It is a cross-disciplinary collaboration, which is necessary in order to tackle in a new and exciting way the problem of fugitive emissions of methane and volatile hydrocarbons from installations such as refineries, petrochemical plants, carbon-capture and storage facilities and landfill sites. These emissions cost the energy sector up to $5B per year, account for 12% of greenhouse gas emissions and jeopardise worker safety and public health. Our idea uses mid-infrared laser light to sense the presence of hydrocarbons by looking for characteristic absorptions at wavelengths specific to individual chemical species. Such "gas absorption spectroscopy" is far from new, but we will implement it in a radically different way to conventional approaches. Normally, optical gas detection works by transmitting a single-wavelength through a gas and looking for an intensity change. For fugitive emissions sensing, this is implemented using a technique called DIAL, which shines an intense beam into the air and detects the weak backscattering of this light from particles in the air (Mie scattering). By looking for small differences in the backscattered intensity between two closely-spaced wavelengths, DIAL can sense the presence of one (and only one) chemical species. Its main drawbacks are the weakness of the returned light (after all, air is a very poor reflector!) and its sensitivity only to one chemical species in any given set-up. The gold standard for lab-based chemical identification is Fourier-transform spectroscopy (FTS), which uses a source similar to a filament light-bulb to explore absorptions over a massive wavelength range all at once. Sadly, such thermal light sources have very poor beam quality, so cannot be transmitted over the long distances appropriate to environmental sensing. In 2004, Heriot-Watt demonstrated that broadband laser light could be used for FTS, combining the wavelength coverage of a thermal source with the beam quality of a laser. This is a game changer for implementing FTS over a long path length as required in environmental sensing, but (for reasons of signal-to-noise) is incompatible with a geometry in which the returned light is very weak. Unmanned aerial vehicle (UAV, or drone) technology has now reached a level of maturity that we can conceive of flying a retroreflector on a UAV to provide a highly efficient means of returning the laser light to a ground-based detector. This concept, which we call DRone-Assisted FTS (DRAFTS), immediately offers improved capabilities over the current state-of-the-art including: 1. Acquisition of concentration and flux maps of multiple chemicals, enabled by using broadband mid-infrared light and allowing correlations to be established and causal effects to be inferred. 2. Sensing with greater range and in diverse atmospheric conditions, since the UAV-mounted retroreflector eliminates the reliance on airborne particles and offers 10,000 times greater efficiency. 3. Deployment in a wider range of scenarios, exploiting the compactness of solid-state lasers, such as using a travelling laser source tracked by the UAV to survey emissions along a road or pipeline. Working with two key partners -- NPL (a leader in fugitive emissions sensing) and Chromacity (a femtosecond laser manufacturer) -- we aim to evaluate DRAFTS and develop it to a level where we can prove its utility in a simulated fugitive emissions field trial. Our partners are contributing £85K toward the project, and span the supply chain from manufacturer to end-user, thus providing critical opportunities for early commercialization of the DRAFTS concept.