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.

The past few decades have witnessed an explosive growth in the semiconductor material and device technologies and their profound impact in the shaping of modern society. After experiencing the booming development of personal computer (PC) technology in the 1990s and the upsurge of the Internet in the 2000s, we are embracing a new age of the Internet of Things. As the explosive growth of Internet Protocol (IP) traffic is driving data centres to the so-called "Zettabyte Era", today's electrical interconnects quickly became the bottleneck due to ohmic loss and RC delays of copper wires. Optical interconnects promise to break the bottleneck by enabling data in computers moving both across chips and from chip to chip through photons. Photons are electromagnetic waves with very high frequencies. They can travel at the speed of light and they are super-efficient information carriers. The realisation of optical interconnects requires all optical components from passive to active devices to be integrated on the same silicon-on-insulator platform. Despite great success in developing silicon-based light modulation and detection, the lack of an efficient light emitter due to the indirect bandgap properties of silicon continues to pose a major roadblock. In contrast to silicon, most of III-V compound semiconductors have a direct bandgap with excellent photon absorption and emission efficiency. It is widely perceived that integrating III-V semiconductors, the best available materials for light emitters, on silicon could unpin the transition from electrical to optical interconnects. Epitaxial growth of III-V materials in the desired areas on silicon offers a scalable, low-cost and high-throughput scheme to bring optical capabilities to silicon integrated circuits. However, there are several fundamental challenges associated with material incompatibility, including a large mismatch in the lattice constants and thermal expansion coefficients, and the growth of polar materials on non-polar substrates. Conventional III-V/Si epitaxy circumvents these challenges through multiple buffer layers on bulk silicon wafers. However, thick buffers limit process throughput and present a big barrier for efficient light coupling to the underlying silicon waveguides. In this project, an advanced epitaxy process will be developed to enable an III-V on insulator (XOI) structure integrated on silicon wafers. By taking advantage of the crystallographic geography and selective area growth in confined spaces, we aim to achieve dislocation-free micro-sized thin films on insulators without requesting complex buffer designs. Such a buffer-less platform can potentially support intimate integration of III-V compound semiconductors with silicon waveguides and open enormous opportunities in Si photonics. As a proof-of-concept demonstration, micro-disk lasers will be fabricated to validate the optical quality of the III-V structures and highlight its potential for photonics integration.

This proposal seeks funding to acquire a stepper and associated wafer coater, tools to enable photolithographic patterning of semiconductor wafers for device and circuit fabrication. The stepper will be located at Southampton University in the recent £120m cleanroom complex. It will relieve the bottleneck within the cleanroom, an electron beam lithography tool, which is a slower alternative patterning tool. This will increase capacity within the cleanroom complex and facilitate and underpin a wealth of world class research. Not only will research at Southampton be enhanced, but Southampton (SOU), Glasgow (GLA), and Surrey (SUR) universities will pool resources to establish a Silicon Photonics Fabrication Capability within the UK, to facilitate an increasing demand for the fabrication of Silicon Photonics devices from the UK's premier researchers. This will encourage wider usage of world class equipment within the UK, in line with EPSRC policy. We seek funding for both the equipment and 3.5 RAs across the 3 institutions, over a 4 year period, to establish and deliver the Capability. Access to a very significant inventory of additional equipment at these 3 universities will be facilitated. The Capability is extremely timely, as silicon foundry services around the world are moving towards a model in which standard platforms and devices will be offered, making it more difficult for researchers to carry out innovative work at the device level, or in non-standard platforms. The proposal is supported by 36 members of academic staff at Southampton, with a total current research portfolio of projects valued in excess of £88m. Furthermore we have 10 project partners who will take part in the use and assessment of the silicon photonics capability by designing and subsequently testing fabricated devices. Their total in-kind contribution is valued at £793,300. These partners have expressed an interest in using the capability after the project has been completed. In addition we have contacted a few example potential users from within the industrial sector (SMEs), and from around the world who have also provided letters of support indicating that they would use the capability after the project is complete. Taking this net proposed usage, it is clear that the equipment will be sustained beyond the period of the funded project. The Southampton users alone need only generate a tiny fraction (0.2%) of their research portfolio to cover running costs and depreciation. Consumables will increase with usage, but clearly, the silicon photonics capability will generate paying users, to further sustain the capability beyond the project, which will, in turn, allow UK researchers to compete effectively on the world stage in the buoyant field of silicon photonics. Beyond the 4 year project, the Silicon Photonics Capability will be operated by the commercial arms of the 3 partner universities, all of whom have provided letters of support confirming their ongoing participation.

We are living in an increasingly digitalised world where data has become critical to all aspects of human life. Today's data centres are consuming about 3 percent of the global electricity supply and this number is likely to triple in the next decade. Remarkably, more than 50% of the power consumption in high-performance computing and data centres is associated with moving information around, rather than processing it. The current COVID-19 pandemic highlights the importance of healthcare monitoring and remote working using high speed broadband connections. Optical communications is essential to accommodate the need for high speed and bandwidth, while at the same time reducing the power required. In the meantime, 3D imaging and sensing is pushing the next revolution in consumer electronics by facilitating artificial intelligence (AI)-powered devices. LiDAR, or Light Detection and Ranging, is one of the key technologies enabling this market growth with anticipated market share reaching $6 billion by 2024, 70% of which dedicated to automotive applications. From telecommunications to sensing applications, photons have proven to be the most efficient platform. As optical communication is penetrating to shorter and shorter distances and the 3D imaging and sensing expanding across the consumer, automotive, medical and industry/commercial sectors, the photonics manufacturing industry is on the verge of technological advancements. However, high cost, low volume capacity and limited scalability of the photon-based platform has become the bottleneck hindering cutting-edge technologies entering mass production. In this regard, integrating bulky, expensive optical components (the lasers, modulators, amplifiers, detectors and lenses) onto a much affordable and scalable platform like silicon is being much sought after by major industry and academic groups. Over the last six decades, silicon has driven the production of new technologies based on electrons at ever astounding volumes. Looking ahead, the silicon platform can be leveraged as a means to overcome the scalability, manufacturing and system architecture challenges experienced by photonics industry, impacting a range of emerging markets where small form factor, low-cost manufacturing and power efficiency are figures of merit. In this project, we aim to integrate high-performance lasers and amplifiers operating at the strategically important C-band at 1550 nm onto the scalable silicon platform. These devices are one of the most critical components enabling long-haul optical fibre communications, inter-data centre optical interconnect and emerging 3D imaging and sensing technologies including eye-safe LiDAR chips. Leveraging the complementary growth techniques of molecular beam epitaxy (MBE) and metal organic chemical vapour deposition (MOCVD), we will incorporate manufacturable nanostructures as the gain medium to realise advanced devices surpassing state-of-the-art. Several routes will be explored to overcome the challenges in growing these materials and devices onto silicon towards fully integrated photonic platforms, opening up the opportunity for low cost and high volume mass production.

Photonics is one of six EU "Key Enabling Technologies. The US recently announced a $200M programme for Integrated Photonics Manufacturing to improve its competiveness. As a UK response, the research proposed here will advance the pervasive technologies for future manufacturing identified in the UK Foresight report on the Future of Manufacturing, improving the manufacturability of optical sensors, functional materials, and energy-efficient growth in the transmission, manipulation and storage of data. Integration is the key to low-cost components and systems. The Hub will address the grand challenge of optimising multiple cross-disciplinary photonic platform technologies to enable integration through developing low-cost fabrication processes. This dominant theme unites the requirements of the UK photonics (and photonics enabled) industry, as confirmed by our consultation with over 40 companies, Catapults, and existing CIMs. Uniquely, following strong UK investment in photonics, we include most of the core photonic platforms available today in our Hub proposal that exploits clean room facilities valued at £200M. Research will focus on both emerging technologies having greatest potential impact on industry, and long-standing challenges in existing photonics technology where current manufacturing processes have hindered industrial uptake. Platforms will include: Metamaterials: One of the challenges in metamaterials is to develop processes for low-cost and high-throughput manufacturing. Advanced metamaterials produced in laboratories depend on slow, expensive production processes such as electron beam writing and are difficult to produce in large sizes or quantities. To secure industrial take up across a wide variety of practical applications, manufacturing methods that allow nanostructure patterning across large areas are required. Southampton hosts a leading metamaterials group led by Prof Zheludev and is well positioned to leverage current/future EPSRC research investments, as well as its leading intellectual property position in metamaterials. High-performance special optical fibres: Although fibres in the UV and mid-IR spectral range have been made, few are currently commercial owing to issues with reliability, performance, integration and manufacturability. This platform will address the manufacturing scalability of special fibres for UV, mid-IR and for ultrahigh power sources, as requested by current industrial partners. Integration with III-V sources and packaging issues will also be addressed, as requested by companies exploiting special fibres in laser-based applications. In the more conventional near-infrared wavelength regime, we will focus on designs and processes to make lasers and systems cheaper, more efficient and more reliable. Integrated Silicon Photonics: has made major advances in the functionality that has been demonstrated at the chip level. Arguably, it is the only platform that potentially offers full integration of all the key components required for optical circuit functionality at low cost, which is no doubt why the manufacturing giant, Intel, has invested so much. The key challenge remains to integrate silicon with optical fibre devices, III-V light sources and the key components of wafer-level manufacture such as on line test and measurement. The Hub includes the leading UK group in silicon photonics led by Prof Graham Reed. III-V devices: Significant advances have been made in extending the range of III-V light sources to the mid-IR wavelength region, but key to maximise their impact is to enable their integration with optical fibres and other photonics platforms, by simultaneous optimisation of the III-V and surrounding technologies. A preliminary mapping of industrial needs has shown that integration with metamaterial components optimised for mid-IR would be highly desirable. Sheffield hosts the EPSRC III-V Centre and adds a powerful light emitting dimension to the Hub.