Lasers are found in many aspects of modern technology and are an essential tool for industry. The ultraviolet (uv) region of the spectrum is especially useful: for example, the minute circuitry used in modern electronics owes its existence to a photographic process in which silicon chips are exposed to uv light. However, the production of uv lasers presents a formidable technical challenge. The light itself is highly energetic and can causing damage to materials. Further, intense uv light has a polarising effect and acts like an optical 'tractor beam': microscopic particles are drawn to the point of highest intensity and get 'burnt' onto sensitive light-transmitting surfaces. While it is difficult to generate uv light, the incentive to succeed is great. Multi-billion-dollar industries are dependent on it with applications in chip manufacture, medical instrumentation, automotive industry, and environmental sensing. While commercial solutions do exist, the market is by no means closed to innovation with existing technology being either unreliable or complex. Cost is also a large factor with embedded laser systems contributing a substantial part to the value of advanced machinery. This project aims to bring together the know-how acquired from many years of dedicated research at the University of Glasgow together with the manufacturing capability of Skylark Lasers. The essential components of the laser will be fused together using hydroxide catalysis bonding to form a compact, monolithic assembly or 'bullet' laser. This innovation offers unique advantages over current technology: the laser will have reduced size and complexity and improved mechanical rigidity; it will also address the inherent issue of damage at optical surfaces. We anticipate that products based on this technology will gain significant market traction, leading to commercial success for the company and, ultimately, growth for UK high-tech industry. A primary market objective is to replace uv gas lasers of which there are around 100,000 operating globally. These consume 1000 times more energy than solid-state alternatives and have a much larger footprint. Their displacement from the market would have a significant environmental impact, in vastly reducing energy consumption, and would also remove carcinogen chemicals from the production cycle. Another application with an environmental impact is the use of uv LIDAR to predict wind conditions as a means of enhancing wind turbine efficiency. We envisage devices embedded within industrial systems for spectroscopy, microscopy, chip inspection and sterilisation. The University of Glasgow is a major partner in the Laser Interferometer Gravitational-Wave Observatory, supported through STFC's core programme, and their expertise in hydroxide catalysis bonding has been instrumental to the success of this ground-breaking project. Skylark Lasers is an early-stage SME set to grow rapidly over the coming years having attracted significant investment for the development of its portfolio of solid-state lasers. A CASE studentship will provide a focal point for collaboration between researchers at the University of Glasgow and technologists at Skylark Lasers. The company will benefit from know-how acquired by the student and a particular goal of the placement following the PhD (CASE plus) will be to enable the company to produce fused assemblies in-house and so develop a new product line. For the university, this will be a striking example of how they can make an impact on the UK economy through knowledge transfer and will demonstrate the spin-off benefit of investment in fundamental research.

Ultrafast lasers, those producing TIME-DOMAIN periodic sequences of ~100 femtosecond-duration pulses, also exhibit remarkable properties in the FREQUENCY DOMAIN, in which as "frequency combs" they serve as "wavelength rulers", enabling precision measurements of wavelength for spectroscopic and metrology applications. Despite maturing fibre-comb technology and steady progress in integrated optical combs, there is still no universal paradigm for the robust, compact and modular frequency-comb sources that are urgently needed for integration in future systems like optical atomic clocks. Building on recent EPSRC-funded research, which led to exciting new concepts in diode-pumped Kerr-lens-modelocked laser designs and engineering, we propose to develop a versatile and robust laser-frequency-comb architecture with broad applicability to a variety of industrial and academic sectors. We focus on GHz-rate diode-pumped solid-state ultrafast lasers as a platform technology offering efficiency, small size, robustness, high average powers, short pulses, low phase noise and high modal powers directly from the laser -- a suite of parameters which makes these lasers attractive for diverse applications in navigation, communications, dimensional metrology, spectroscopy and defence. Our programme envisions a platform technology that extends our recent demonstration of diode-pumped three-element Kerr-lens-modelocked Ti:sapphire laser architectures (800 nm) to Er,Yb:glass (1560 nm) and Cr:ZnSe (2400 nm), with designs optimised by Kerr-nonlinearity modelling. The wavelength coverage of these lasers will be enhanced by using tapered-fibres to generate broadband supercontinua from nJ pulses. Power-scaling in semiconductor optical amplifiers -- a technology perfectly matched to GHz-pulse amplification -- will be explored as a route to ultra-compact, high-power GHz systems. By adapting the 3-element laser design to configure two lasers in one cavity, we will demonstrate a simple and powerful dual-comb embodiment for high-speed distance metrology and spectroscopy. Proven designs will be progressed to higher TRL by using our proprietary micro-optical bonding technique to realise high-stability, self-starting laser configurations, suitable for evaluation and integration in applications. The project is supported by 8 academic and industrial partners who have offered cash and in-kind contributions totalling >£3M, representing considerable co-funding alongside EPSRC's investment. Their letters of support evidence the significance of the proposed technology for their businesses and illustrate their commitment to our research and development programme. As well as creating new academic knowledge and significant new engineering capabilities, the application of the compact ultrafast laser technologies we propose to develop could deliver profound socioeconomic impacts. For example, integrating compact combs into industrial metrology systems could enable lower-waste digital precision manufacturing; replacing 1550-nm cw lasers with GHz-rate ultrafast lasers could improve the resilience of Tb/s eye-safe free-space communications in all weathers, connecting remote communities; compact mid-IR sources could facilitate low-cost, multi-species sensors for 'net-zero'; and integrable Ti:sapphire combs could power future GNSS systems for distributing standard time and position across the globe. Each of the above examples maps to an industrial or academic collaboration embodied in our proposed programme of research, thus providing a realistic pathway to each of the impacts described.

Quantum Technology is based on quantum phenomena that govern physics on an atomic scale, enabling key breakthroughs that enhance the performance of classical devices and allow for entirely new applications in communications technology, imaging and sensing, and computation. Quantum networks will provide secure communication on a global scale, quantum sensors will revolutionise measurements in fields such as geology and biomedical imaging, and quantum computers will efficiently solve problems that are intractable even on the best future supercomputers. The economic and societal benefit will be decisive, impacting a wide range of industries and markets, including engineering, medicine, finance, defence, aerospace, energy and transport. Consequently, Quantum Technologies are being prioritised worldwide through large-scale national or trans-national initiatives, and a healthy national industrial Quantum Technology ecosystem has emerged including supply chain, business start-ups, and commercial end users. Our Centre for Doctoral Training in Applied Quantum Technologies (CDT-AQT) will address the national need to train cohorts of future quantum scientists and engineers for this emerging industry. The training program is a partnership between the Universities of Strathclyde, Glasgow and Heriot-Watt. In collaboration with more than 30 UK industry partners, CDT-AQT will offer advanced training in broad aspects of Quantum Technology, from technical underpinnings to applications in the three key areas of Quantum Measurement and Sensing, Quantum Computing and Simulation, and Quantum Communications. Our programme is designed to create a diverse community of responsible future leaders who will tackle scientific and engineering challenges in the emerging industrial landscape, bring innovative ideas to market, and work towards securing the UK's competitiveness in one of the most advanced and promising areas of the high-tech industry. The quality of our training provision is ensured by our supervisors' world-class research backgrounds, well-resourced research environments at the host institutions, and access to national strategic facilities. Industry engagement in co-creation and co-supervision is seen as crucial in equipping our students with the transferable skills needed to translate fundamental quantum physics into practical quantum technologies for research, industry, and society. To benefit the wider community immediately, we will make Quantum Technologies accessible to the general public through dedicated outreach activities, in which our students will showcase their research and exhibit at University Open Days, schools, science centres and science festivals.

In a consortium led by Heriot-Watt with St Andrews, Glasgow, Strathclyde, Edinburgh, Dundee, Huddersfield and NPL, the "EPSRC CDT in Use-Inspired Photonic Sensing and Metrology" responds to the focus area of "Meeting a User-Need and/or Supporting Civic Priorities" and aligns to EPSRC's Frontiers in Engineering & Technology priority and its aim to produce "tools and technologies that form the foundation of future UK prosperity". Our theme recognises the key role that photonic sensing and metrology has in addressing 21st century challenges in transport (LiDAR), energy (wind-turbine monitoring), manufacturing (precision measurement), medicine (disease sensors), agri-food (spectroscopy), security (chemical sensing) and net-zero (hydrocarbon and H2 metrology). Building on the success of our earlier centres, the addition of NPL and Huddersfield to our team reflects their international leadership in optical metrology and creates a consortium whose REF standing, UKRI income and industrial connectivity makes us uniquely able to deliver this CDT. Photonics contributes £15.2bn annually to the UK economy and employs 80,000 people--equal to automotive production and 3x more than pharmaceutical manufacturing. By 2035, more than 60% of the UK economy will rely on photonics to stay competitive. UK companies addressing the photonic sensing and metrology market are therefore vital to our economy but are threatened by a lack of doctoral-level researchers with a breadth of knowledge and understanding of photonic sensing and metrology, coupled with high-level business, management and communication skills. By ensuring a supply of these individuals, our CDT will consolidate the UK industrial knowledge base, driving this high-growth, export-led sector whose products and services have far-reaching impacts on our society. The proposed CDT will train 55 students. These will comprise at least 40 EngD students, characterised by a research project originated by a company and hosted on their site. A complementary stream of up to 15 PhD students will pursue industrially relevant research in university labs, with more flexibility and technical risk than in an EngD project. In preparing this bid, we invited companies to indicate their support, resulting in £5.5M cash commitments for 102 new students, considerably exceeding our target of 55 students, and highlighting industry's appetite for a CDT in photonic sensing and metrology. Our request to EPSRC for £6.13M will support 35 students, with the remaining students funded by industrial (£2.43M) and university (£1.02M) cash contributions, translating to an exceptional 56% cash leverage of studentship costs. The university partners provide 166 named supervisors, giving the flexibility to identify the most appropriate expertise for industry-led EngD projects. These academics' links to >120 named companies also ensure that the networks exist to co-create university-led PhD projects with industry partners. Our team combines established researchers with considerable supervisory experience (>50 full professors) with many dynamic early-career researchers, including a number of prestigious research fellowship holders. A 9-month frontloaded residential phase in St Andrews and Edinburgh will ensure the cohort gels strongly, equipping students with the knowledge and skills they need before starting their research projects. These core taught courses, augmented with electives from the other universities, will total 120 credits and will be supplemented by accredited MBA courses and training in outreach, IP, communication skills, RRI, EDI, sustainability and trusted-research. Collectively, these training episodes will bring students back to Heriot-Watt a few times each year, consolidating their intra- and inter-cohort networks. Governance will follow our current model, with a mixed academic-industry Management Committee and an International Advisory Committee of world-leading experts.