Silicon Photonics is currently transforming data communications, and beginning to impact longer reach applications. However, Silicon Photonics is now maturing and current commercially available transceivers mainly utilise modulators operating at 25Gb/s. Laboratory demonstrators for next generation systems either use multiple parallel lanes of 25Gb/s devices, or perhaps more complex modulation techniques to achieve higher aggregate data rates. Even the fastest research modulators, when integrated with drivers, operate up to approximately 50Gb/s OOK (or corresponding PAM4 modulation to reach a net aggregate speed of 100Gb/s). Researchers worldwide are trying to improve such modulators to squeeze the last few percentage points of improved performance out of these devices, or are turning to integration of other materials, which increases fabrication complexity and cost, and potentially reduces yield. In this work we have invented a way to improve the modulator/driver combination not by a few percent, but by 100%, which will lead to dramatic improvements in data rate, power consumption, and cost of implementation. We will demonstrate 100Gb/s OOK and 200Gb/s PAM4, as well as a novel Optical Time Division Multiplexing (OTDM) system. In effect, we have found a way to transfer functions that were traditionally done in the electronic domain, to the optical domain, saving cost and energy and dramatically improving performance. The proposal provides detailed simulations of the proposed work as preparatory demonstration of the viability of the new techniques. This includes typical characteristics of modulators previously fabricated at the Southampton, which will now be operated in a different mode. Consequently, we are confident that the chances of success are very high. Electronic drivers will be designed at Southampton and subcontracted to TSMC in Taiwan for fabrication. All optical devices will be fabricated at Southampton using the Silicon Photonics Foundry service called CORNERSTONE. The new approach has already led to 2 patent applications, and we suspect others will follow as we progress with the research. Both investigators and the research investigator are inventors, so the team is ideally placed to carry out the work.

From an Information and Communication Technology (ICT) perspective, the 21st century is characterized by an explosion of requests for communication capabilities, high-performance computing, and cloud storage. Over the last few years, global Internet traffic has been growing exponentially. In this picture, transporting such an amount of data with existing electrical- interconnects and switching technologies will soon reach the "bottleneck" in terms of thermal loading, capacity, latency and power consumption. Optical- interconnects and switch fabrics combined with photonic integrated circuits (PICs) are seen as one of the most promising routes to push such limits. Silicon (Si) photonics is now considered as a reliable photonic integration platform. The beauty of Si Photonics stems from its ability to integrate microelectronics and photonics on a single Si chip utilizing standard CMOS IC technology. An important subset of this area is hetero-integration of III-Vs on Si, where the aim is the make use of III-V materials, with superior optical properties, to provide an efficient optical gain medium to circumvent the fundamental physical limitation of Si, i.e. Si cannot efficiently emit light, yet keeping the capability of light-routing, modulating, detecting and cost advantages of Si. In a breakthrough development, the investigators' group in UCL have shown that it is possible to grow epitaxially high-performance quantum dot (QD) lasers directly on Si substrates, opening up the possibility to monolithically integrate various types of III-V optoelectronic devices on Si. The pace of research on monolithic III-V/Si integration has then been dramatically accelerated and an increasing number of prestigious research groups including Bowers' group at UCSB and Arakawa's group at Tokyo University, and major Si chip companies, i.e. Intel, are currently devoting considerable programmes in this area. In addition to III-V/Si lasers, monolithic III-V/Si semiconductor optical amplifiers (SOAs) are also attracting significant interest as the key components for next-generation photonic integrated optical- interconnects and switching fabrics, as the application of SOAs is not limited only to compensate for loss and maintain signal levels as the signal propagates throughout a large number of optical components within the PICs, it is also used as a mature gating element for optical switches and has the advantages of ease of control, smaller footprint, low operating voltage, high ON/OFF extinction ratio, and fast transition times of the order of nanoseconds. However, such a III-V/Si SOA has not been developed to date. Building on the established expertise in monolithic III-V/Si QD lasers at UCL, this project proposal aims to develop the world's first monolithic III-V QD SOA on CMOS-compatible on-axis Si (001) substrates. In contrast to conventional native substrate based SOAs or III-V/Si SOAs using either flip-chip bonding or wafer bonding, the proposed method is fundamentally different, since the III-V SOAs will be integrated on Si by direct epitaxial methods, offering the possibility to achieve high-yield, low-cost and large-scale Si-based PICs, which is expected to be the technology platform to address next-generation optical- interconnect and switching solutions. With further development in Si photonics, i.e., providing the microelectronics world with the ultra-large-scale integration of photonic components, there will be scope to target applications in important areas such as consumer electronics, high-performance computing, medical and sensor solutions, and defence. This project will benefit from guidance from and joint work with both industrial as well as academic partners and will leverage major UK-based industrial and academic strengths in materials (e.g., CSC, EPSRC NEF) device processing (e.g., EPSRC CSHub, Glasgow) and photonics (e.g., Rockley, Lumentum), who are also well positioned to exploit this research.

Silicon Photonics, the technology of electronic-photonic circuits on silicon chips, is transforming communications technology, particularly data centre communications, and bringing photonics to mass markets, utilising technology in the wavelength range 1.2 micrometres - 1.6 micrometres. Our vision is to extend the technical capability of Silicon Photonics to Mid -Infrared (MIR) wavelengths (3-15 micrometres), to bring the benefits of low cost manufacturing, technology miniaturisation and integration to a plethora of new applications, transforming the daily lives of mass populations. To do this we propose to develop low-cost, high performance, silicon photonics chip-scale sensors operating in the MIR wavelength region. This will change the way that healthcare, and environmental monitoring are managed. The main appeal of the MIR is that it contains strong absorption fingerprints for multiple molecules and substances that enable sensitive and specific detection (e.g. CO2, CH4, H2S, alcohols, proteins, lipids, explosives etc.) and therefore MIR sensors can address challenges in healthcare (e.g. cancer, poisoning, infections), and environmental monitoring (trace gas analysis, climate induced changes, water pollution), as well as other applications such as industrial process control (emission of greenhouse gases), security (detection of explosives and drugs at airports and train stations), or food quality (oils, fruit storage), to name but a few. However, MIR devices are currently realised in bulk optics and integrated MIR photonics is in its infancy, and many MIR components and circuits have either not yet been developed or their performance is inferior to their visible/near-IR counterparts. Research leaders from the Universities of Southampton, Sheffield and York, the University Hospital Southampton and the National Oceanography Centre will utilise their world leading expertise in photonics, electronics, sensing and packaging to unleash the full potential of integrated MIR photonics. We will realise low cost, mass manufacturable devices and circuits for biomedical and environmental sensing, and subsequently improve performance by on-chip integration with sources, detectors, microfluidic channels, and readout circuits and build demonstrators to highlight the versatility of the technology in important application areas. We will initially focus on the following applications, which have been chosen by consulting end users of the technology (the NHS and our industrial partners): 1) Therapeutic drug monitoring (e.g. vancomycin, rifampicin and phenytoin); 2) Liquid biopsy (rapid cancer diagnostics from blood samples); 3) Ocean monitoring (CO2, CH4, N2O detection).

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 sensing, processing and transport of information is at the heart of modern life, as can be seen from the ubiquity of smart-phone usage on any street. From our interactions with the people who design, build and use the systems that make this possible, we have created a programme to make possible the first data interconnects, switches and sensors that use lasers monolithically integrated on silicon, offering the potential to transform Information and Communication Technology (ICT) by changing fundamentally the way in which data is sensed, transferred between and processed on silicon chips. The work builds on our demonstration of the first successful telecommunications wavelength lasers directly integrated on silicon substrates. The QUDOS Programme will enable the monolithic integration of all required optical functions on silicon and will have a similar transformative effect on ICT to that which the creation of silicon integrated electronic circuits had on electronics. This will come about through removing the need to assemble individual components, enabling vastly increased scale and functionality at greatly reduced cost.