This proposal is focused on fibre lasers and will develop a new class of compact (centimetre length), narrow-linewidth (kHz and sub-kHz) fibre laser based on fibre Bragg gratings and Raman gain in silica-based fibres, the so-called Raman Distributed Feedback (R-DFB) fibre laser. This type of laser exhibits superior performance to those of standard rare-earth doped DFB fibre lasers in terms of efficiency, coherence length, low noise-level, and wavelength agility, and will allow for unconstrained single-frequency wavelength operation across the full transmission-window of silica. Continuous wave (CW) output power values up to 100mW will be targeted and the work will demonstrate R-DFB lasers in both germanosilicate and phosphosilicate fibres, each of which allows for different levels of Raman frequency shifts, at wavelengths applicable to LIDAR, high-spectral brightness and long coherence length applications incl., nonlinear optics applications, in particular four-wave-mixing (FWM), and spectroscopic sensing incl., trace sensing of targeted molecular species of importance for environmental monitoring. For ease of operation and integration, and for reduced complexity and cost, the work will also demonstrate direct laser diode-pumping of the developed R-DFB lasers. These lasers will help realise an increasingly important unmet need for low noise kHz linewidth sources in several wavelength bands where currently no such sources are available.

Technologies underpin economic and industrial advances and improvements in healthcare, education and societal and public infrastructure. Technologies of the future depend on scientific breakthroughs of the past and present, including new knowledge bases, ideas, and concepts. The proposed international network of interdisciplinary centre-to-centre collaborations aims to drive scientific and technological progress by advancing and developing a new science platform for emerging technology - the optical frequency comb (OFC) with a range of practical applications of high industrial and societal importance in telecommunications, metrology, healthcare, environmental applications, bio-medicine, food industry and agri-tech and many other applications. The optical frequency comb is a breakthrough photonic technology that has already revolutionised a range of scientific and industrial fields. In the family of OFC technologies, dual-comb spectroscopy plays a unique role as the most advanced platform combining the strengths of conventional spectroscopy and laser spectroscopy. Measurement techniques relying on multi-comb, mostly dual-comb and very recently tri-combs, offer the promise of exquisite accuracy and speed. The large majority of initial laboratory results originate from cavity-based approaches either using bulky powerful Ti:Sapphire lasers, or ultra-compact micro-resonators. While these technologies have many advantages, they also feature certain drawbacks for some applications. They require complex electronic active stabilisation schemes to phase-lock the different single-combs together, and the characteristics of the multi-comb source are not tuneable since they are severely dictated by the opto-geometrical parameters of the cavity. Thus, their repetition rates cannot be optimised to the decay rates of targeted samples, nor their relative repetition rates to sample the response of the medium. Such lack of versatility leads to speed and resolution limitations. These major constraints impact the development of these promising systems and make difficult their deployment outside the labs. To drive OFC sources, and in particular, multi-comb source towards a tangible science-to-technology breakthrough, the current state of the art shows that a fundamental paradigm shift is required to achieve the needs of robustness, performance and versatility in repetition rates and/or comb optical characteristics as dictated by the diversity of applications. In this project we propose and explore new approaches to create flexible and tunable comb sources, based on original design concepts. The novelty and transformative nature of our programme is in addressing engineering challenges and designs treating nonlinearity as an inherent part of the engineering systems rather than as a foe. Using the unique opportunity provided by the EPSRC international research collaboration programme, this project will bring together a critical mass of academic and industrial partners with complimentary expertise ranging from nonlinear mathematics to industrial engineering to develop new concepts and ideas underpinning emerging and future OFC technologies. The project will enhance UK capabilities in key strategic areas including optical communications, laser technology, metrology, and sensing, including the mid-IR spectral region, highly important for healthcare and environment applications, food, agri-tech and bio-medical applications. Such a wide-ranging and transformative project requires collaborative efforts of academic and industrial groups with complimentary expertise across these fields. There are currently no other UK projects addressing similar research challenges. Therefore, we believe that this project will make an important contribution to UK standing in this field of high scientific and industrial importance.

Quantum sensing, imaging and timing will deliver transformative advancements across multiple sectors, including healthcare, infrastructure, transportation, environmental sustainability and security. These technologies make seeing the invisible possible: the inside workings of our brains, the infrastructure buried beneath our feet, the polluting gases in the air around us, the cancers lurking in our tissue or the drones in our crowded skies. These are some of the challenges we are poised to address. Our Hub in Quantum Sensing Imaging and Timing (QuSIT) brings together academic experts and industry partners, collaborating to translate cutting-edge research into tangible innovations. QuSIT will capitalise on a decade of substantial governmental and industrial investments, consolidating expertise and world-class capability from two established UK Hubs: QuantIC, specialising in quantum-enhanced imaging and the UK Sensing and Timing Hub. QuSIT will be a unified centre of excellence, providing thought leadership within the UK's quantum technology landscape, crucial to the National Quantum Strategy. At the heart of QuSIT is a world-leading and diverse team of 45 investigators, comprising both emerging talents and seasoned experts. Their impressive academic track record is complemented by a shared commitment to translating innovation from the laboratory to address real-world challenges. Our researchers have a history of licensing technology to industry and launching their own ventures. The technologies we will exploit are based on both atomic states and entangled photons to create quantum devices that sense and image otherwise invisible optical wavelengths, radio-frequencies, magnetic and gravitational fields, and exploit precision time, including: Optical wavelength translation using non-linear interferometry and non-linear optics Atom interferometry for gravity and gravity gradient sensing Waveguide optics for wavelength conversion Optically pumped magnetometers for zero and high absolute fields Metasurfaces for lightweight and compact optics Wavefront shaping for seeing through obscuration Data fusion of quantum and classical sensor data, using AI and Bayesian Inference Quantum enabled frequency sources to enhance radar systems Our approach revolves around co-creating research with end-users, fostering collaborations between academics and industry players throughout the supply chain, and rigorously testing and refining our innovations through field trials in partnership with our collaborating companies, pursuing new approaches to: Line-of-sight imaging of polluting, or toxic gases and chemicals Monitoring of brain health Screening for concealed and dangerous objects Imaging of underground infrastructure Mid-infrared, holographic microscopes for clinical diagnosis Application of precise timing for the monitoring of congested airspace The hub is supported by companies and other end-users many of which have made significant investments. These include BT, BAE Systems, Department for Transport, Great Ormond Street Hospital, National Grid, National Physical Laboratory, Ordnance Survey and Severn Trent Water. In the increasingly competitive international landscape, QuSIT will provide the vision and have the convening power required to ensure that the UK remains at the forefront of quantum technology internationally, delivering accelerated economic growth and societal benefits through collaboration between academia and industry.

Standard multi-kW fibre lasers are now considered 'commodity' routinely produced by multiple manufacturers worldwide and are widely used in the most advanced production lines for cutting, welding, 3D printing and marking a myriad of materials from glass to steel. The ability to precisely control the properties of the output laser beam and to focus it on the workpiece makes high-power fibre lasers (HPFLs) indispensable to transform manufacturing through adaptable digital technologies. As we enter the Digital Manufacturing/Industry 4.0 era, new challenges and opportunities for HPFLs are emerging. Modern product life-cycles have never been shorter, requiring increased manufacturing flexibility. With disruptive technologies like additive manufacturing moving into the mainstream, and traditional subtractive techniques requiring new degrees of freedom and accuracy, we expect to move away from fixed, 'fit-for-all' beams to 'on-the-flight' dynamically reconfigurable 'shaped light' with extensive range of beam shapes, shape frequency and sequencing, as well as 3D focus steering. It is also conceivable that the future factory floor will get 'smarter', undergoing a rapid evolution from dedicated static laser stations to robotic flexible/reconfigurable floorplans, which will require 'smart photon delivery' over long distances to the workpiece. Such a disruptive transition requires a new advanced generation of flexible laser tools suitable for the upcoming 4th industrial revolution. Light has four characteristic properties, namely wavelength, polarization, intensity, and phase. In addition, use of optical fibres enables accurate control and shaping in the spatial domain through a variety of well-guided modes. Invariably, all photonic devices function by manipulating some of these properties. Despite their acclaimed success, so far HPFLs are used rather primitively as single-channel, single colour, mostly unpolarised and unshaped, raw power providers and remain at a relatively early stage (stage I) of their potential for massive scalability and functionality. Moreover, further progress in fibre laser power scaling, beam stability and efficiency is hindered by the onset of deleterious nonlinearities. On the other hand, the other unique attributes, such as extended 'colour palette', extensively controllable polarisation and beam shaping on demand, as well as massive 'parallelism' through accurate phase control remain largely unexplored. Use of these characteristics is inherent and comes natural to fibre technology and can add unprecedented functionality to a next generation of 'smart photon engines' and 'smart photon pipes' in a stage II of development. This PG will address the stage II challenges, confront the science and technology roadblocks, seek innovative solutions, and unleash the full potential of HPFLs as advanced manufacturing tools. Our aim is to revolutionise manufacturing by developing the next generation of reconfigurable, scalable, resilient, power efficient, disruptive 'smart' fibre laser tools for the upcoming Digital Manufacturing era. Research for the next generation of manufacturing tools, like in HiPPo PG, that will drive economic growth should start now to make the UK global leaders in agile laser manufacturing - enabling sustainable, resource efficient high-value manufacturing across sectors from aerospace, to food, to medtech devices and automotive. In this way the UK can repatriate manufacturing, rebalance the economy, create high added-value jobs, and promote the green agenda through efficient manufacturing. It will also enhance our defence sovereign capability, as identified by the Prime Minister in the Integrated Review statement to the House of Commons in November 2020.

Quantum technologies exploit the intriguing properties of matter and light that emerge when the randomizing processes of everyday situations are subdued. Particles then behave like waves and, like the photons in a laser beam, can be split and recombined to show interference, providing sensing mechanisms of exquisite sensitivity and clocks of exceptional accuracy. Quantum measurements affect the systems they measure, and guarantee communication security by destroying cryptographic keys as they are used. The entanglement of different atoms, photons or circuits allows massively powerful computation that promises complex optimizations, ultrafast database searches and elusive mathematical solutions. These quantum technologies, which EPSRC has declared one of its four Mission-Inspired priorities, promise in the near future to stand alongside electronics and laser optics as a major technological resource. In this 'second quantum revolution', a burgeoning quantum technology industry is translating academic research and laboratory prototypes into practical devices. Our commercial partners - global corporations, government agencies, SMEs, start-ups, a recruitment agency and VC fund - have identified a consistent need for hundreds of doctoral graduates who combine deep understanding of quantum science with engineering competence, systems insight and a commercial head. With our partners' guidance, we have designed an exciting programme of taught modules to develop knowledge, skills and awareness beyond the provision of traditional science-focused PhD programmes. While pursuing leading-edge research in quantum science and engineering, graduate students in the EPSRC CDT for Quantum Technology Engineering will follow a mix of lectures, practical assignments and team work, peer learning, workshops, and talks by our commercial partners. They will strengthen their scientific and engineering capabilities, develop their computing and practical workshop skills, study systems engineering and nanofabrication, project and risk management and a range of commercial topics, and receive professional coaching in communication and presentation. An industrial placement and extended study visit will give them experience of the commercial environment and global links in their chosen area, and they will have support and opportunities to break their studies to explore the commercialization of research inventions. A QT Enterprise Club will provide fresh, practical entrepreneurship advice, as well as a forum for local businesses to exchange experience and expertise. The CDT will foster an atmosphere of team working and collaboration, with a variety of group exercises and projects and constant encouragement to learn from and about each other. Students will act as mentors to junior colleagues, and be encouraged to take an active interest in each other's research. They will benefit from the diversity of their peers' backgrounds, across not just academic disciplines but also career stages, with industry secondees and part-time students bringing rich experience and complementary expertise. Students will draw upon the wealth of experience, across all corners of quantum technologies and their underpinning science and techniques, provided by Southampton's departments of Physics & Astronomy, Engineering, Electronics & Computer Science, Chemistry and its Optoelectronics Research Centre. They will be given training and opening credit for the Zepler Institute's nanofabrication facilities, and access to the inertial testing facilities of the Institute of Sound & Vibration research and the trials facilities of the National Oceanography Centre. Our aim is that graduates of the CDT will possess not only a doctorate in the exciting field of quantum technology, but a wealth of knowledge, skills and awareness of the scientific, technical and commercial topics they will need in their future careers to propel quantum technologies to commercial success.