In a consortium led by Heriot-Watt with St Andrews, Glasgow, Strathclyde, Edinburgh and Dundee, this proposal for an "EPSRC CDT in Industry-Inspired Photonic Imaging, Sensing and Analysis" responds to the priority area in Imaging, Sensing and Analysis. It recognises the foundational role of photonics in many imaging and sensing technologies, while also noting the exciting opportunities to enhance their performance using emerging computational techniques like machine learning. Photonics' role in sensing and imaging is hard to overstate. Smart and autonomous systems are driving growth in lasers for automotive lidar and smartphone gesture recognition; photonic structural-health monitoring protects our road, rail, air and energy infrastructure; and spectroscopy continues to find new applications from identifying forgeries to detecting chemical-warfare agents. UK photonics companies addressing the sensing and imaging market are vital to our economy (see CfS) but their success is threatened by a lack of doctoral-level researchers with a breadth of knowledge and understanding of photonic imaging, sensing and analysis, 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 the high-growth export-led sectors of the economy whose photonics-enabled products and services have far-reaching impacts on society, from consumer technology and mobile computing devices to healthcare and security. Building on the success of our CDT in Applied Photonics, the proposed CDT will be configured with most (40) students pursuing an EngD degree, characterised by a research project originated by a company and hosted on their site. Recognizing that companies' interests span all technology readiness levels, we are introducing a PhD stream where some (15) students will pursue industrially relevant research in university labs, with more flexibility and technical risk than would be possible in an EngD project. Overwhelming industry commitment for over 100 projects represents a nearly 100% industrial oversubscription, with £4.38M cash and £5.56M in-kind support offered by major stakeholders including Fraunhofer UK, NPL, Renishaw, Thales, Gooch and Housego and Leonardo, as well as a number of SMEs. Our request to EPSRC for £4.86M will support 35 students, from a total of 40 EngD and 15 PhD researchers. The remaining students will be funded by industrial (£2.3M) and university (£0.93M) contributions, giving an exceptional 2:3 cash gearing of EPSRC funding, with more students trained and at a lower cost / head to the taxpayer than in our current CDT. For our centre to be reactive to industry's needs a diverse pool of supervisors is required. Across the consortium we have identified 72 core supervisors and a further 58 available for project supervision, whose 1679 papers since 2013 include 154 in Science / Nature / PRL, and whose active RCUK PI funding is £97M. All academics are experienced supervisors, with many current or former CDT supervisors. An 8-month frontloaded residential phase in St Andrews and Edinburgh will ensure the cohort gels strongly, and will equip students with the knowledge and skills they need before beginning their research projects. Business modules (x3) will bring each cohort back to Heriot-Watt for 1-week periods, and weekend skills workshops will be used to regularly reunite the cohort, further consolidating the peer-to-peer network. Core taught courses augmented with specialist options will total 120 credits, and will be supplemented by professional skills and responsible innovation training delivered by our industry partners and external providers. Governance will follow our current model, with a mixed academic-industry Management Committee and an independent International Advisory Board of world-leading experts.

This project addresses the need for an energy harvesting method compatible with economic deployment and extended battery life/ self powering for autonomous electronics, focussing on use of innovative patented high efficiency photovoltaics (HEPV) as the energy harvesting medium. The autonomous electronics platform used for the project comprises wireless multiple sensors (carbon dioxide (CO2) /temperature /humidity /light /dew point) combined with embedded data processing and datalogging electronics for use in applications such as building/ home automation, horticulture and medical devices. A key objective is demonstration of HEPV for use in various lighting scenarios, in particular indoor low lighting conditions. Other key activities include power management interface with sensors & embedded electronic modules and use with long life rechargeable thin film batteries and/or super capacitors. The HEPV power harvesting method provides potential for low cost “fit and forget” deployment of autonomous electronics based controllers in smart wireless sensor networks. The consortium includes end user assessment in the building, horticulture and medical sectors.

There is great worldwide interest in the mid-infrared spectral region (2-5 um) as it contains the fundamental absorption bands of a number of pollutant and toxic gases and liquids. These include gases such as carbon dioxide, carbon monoxide and hydrogen chloride which require accurate, in-situ multi-component monitoring in a number of industries such as oil-rigs, coal mines, land-fill sites and car exhausts. Strong absorption bands also exist for drug intermediates, pharmaceuticals, narcotics and biochemicals where the absorption strength is typically 2 orders of magnitude stronger than in the near-infrared allowing highly selective and sensitive detection in the fields of: environmental monitoring, bio-medicine, industrial process control and health and safety. There is also an atmospheric transmission window between 3.6 and 3.8 um which enables free space optical communication and thermal imaging in both civil and military situations as well as the development of infrared countermeasures for homeland security. However, these applications have yet to be fully exploited due to the lack of efficient and affordable light sources and detectors. This work proposes the growth and fabrication of a new light emitting diode (LED) architecture based on indium antimonide (InSb) quantum dots onto low cost silicon (Si) substrates. This will revolutionize how we utilize these devices and lead to a dramatic scaling in the cost and size of the optical systems to enable their widespread uptake. It will also enable the photonic components to be directly embedded into electronic circuits which would open up a new field of mid-infrared photonic integrated circuits. This would generate entirely new technology in areas such as integrated 'lab-on-a-chip' sensors and compact biochips bringing great commercial benefits and opportunities to the UK. In the last few years, there has been significant progress in the development of mid-infrared devices using interband cascade lasers and type II superlattices. However these structures are extremely complex and expensive to fabricate and are grown on gallium antimonide (GaSb) substrates which are of poor quality, high cost (~50 times the cost of Si) and are only available in small sizes. Growth onto silicon would be most desireable to enable cost effective manufacture and to ensure future commercial success. The major obstacle in direct epitaxial growth of III-Vs onto Si is the large lattice mismatch between the III-V/Si interface, resulting in a large density of threading dislocations (TDs) which strongly deteriorate the device performance. This project shall overcome this by implementation of a new device design based on InSb quantum dots on low defect density GaSb buffer layers grown on Si. The key advantages are the mechanical robustness and very low sensitivity of the quantum dots to TD compared to bulk or quantum well structures, and the suppression of non-radiative Auger recombination to increase the quantum efficiency. In a quantum well device, every threading dislocation which propagates through it will act as a non-radiative centre drastically reducing the device performance. However in a QD, each TD will only 'kill' one or a few isolated dots which will not significantly affect device performance providing the TD density in the buffer layer can be reduced to moderate-to-low levels. Low defect density GaSb buffer layers shall be realized through novel 'interfacial misfit arrays (IMF)' and dislocation filtering layers designed to bend and annihilate TD generated at the III-V/Si interface. The Si based mid-infrared LEDs will be developed in close collaboration with academic (University of Southampton and University of Montpellier) and industrial (Compound Semiconductor Technologies and Gas Sensing Solutions) project partners to evaluate device performance for use in practical applications which will help to achieve future commercialisation.

The vision of this project is to develop practical quantum technology for the accurate measurement of electrical currents and to develop high sensitivity detectors for gases such as carbon dioxide, methane (the gas used to heat homes) and carbon dioxide. Single electron transistors allow only one electron to travel through the device when switched on to form the electrical current. If the control gate is switched at a high frequency then the current through the device is simply the frequency times the charge on an electron and by counting the number of electrons, the current can be accurately measured. All such devices to date only work at low temperatures due to the small energy difference between the quantum states required for the transistor. I am proposing to make a single electron transistor which is far smaller than any previous reported device that will have large energies between the quantum states and operate at room temperature. Gas molecules absorb light at very specific wavelengths which in the mid-infrared part of the electromagnetic spectrum correspond to vibrational energy of the bonds which hold the atoms together to form the gas molecule. This provides a molecular fingerprint as each molecule only absorbs specific wavelengths which can therefore be used to identify the gas. Gas detectors already exist for carbon dioxide, carbon monoxide and methane gas by measuring the absorption of light at the molecular fingerprint wavelength but the sensitivity for small battery powered detectors in the home is at the level of parts per million. For many scientific, healthcare, industrial and security applications sensitivities require to be at least a thousand times better. To date systems for measuring at this accuracy are large, bulky and require large lasers. This proposal will use quantum technology to build a far smaller and cheaper chip scale gas detector with parts per billion sensitivity that could be integrated into mobile phones or used for battery power sensors. I am proposing to use the quantum nature of light to produce 2 individual packets of light called photons which will be at the same wavelength and at the same phase where the peaks and troughs of the waves are at the same points in space as the light travels through a waveguide. Heisenburg's uncertainty principle only allows us to measure the amplitude or the phase of the photons with a specific accuracy and the product is a constant. If we squeeze the phase of the light so that the accuracy in measuring the phase is reduced then we can measure the amplitude more accurately since it is only the product of the two that we cannot measure at a higher accuracy. This quantum approach of squeezing light allows far more sensitive measurements that are forbidden in classical measurement systems. The project brings together a range of UK companies, government agencies, standards laboratories and universities to deliver the portable current standard and the high sensitivity gas detector. I will be supplying demonstrators to a range of collaborators who will evaluate the performance with successful devices being transferred to UK companies to help develop next generation products. The project will also train 2 research associates and 2 PhD students in quantum technology.

Semiconductor materials power much of the current economy, through their use in the ubiquitous computer and much else besides. The most common semiconductor is silicon, and this accounts for about 90% of the world market. There are some other types of semiconductor, however, that provide functions that silicon can't address but which are also very important. Examples of these include: gallium arsenide, which is used in satellite receivers and mobile phones for the communications parts; materials based on indium phosphide, which are used in lasers in CD and DVD players and for long distance communications along optical fibres; and materials based on gallium nitride, which are used to make the white light emitting diodes that are now being used for a range of energy efficient lighting and even in car headlights. All of these materials belong to a family known as III-V semiconductors, because they contain a mixture of elements from group 3 and group 5 of the periodic table. III-V semiconductors account for most of the remaining 10% of the electronics industry, and are worth approximately £25bn per year worldwide and growing at about 7%p.a. Unlike the silicon industry, the UK has a significant presence in the manufacture of electronic components based on these materials, as well as systems based upon them, and is in a good position to benefit from the rapid growth in the market. Another member of this III-V semiconductor family in indium antimonide, a compound of indium and antimony, which has the formula InSb. InSb has several interesting properties. Charge carriers can be made to go faster than in any other member of the family and take less voltage to do so. Consequently, this material has the potential to make components that will operate at very high frequencies whilst consuming very little power and so, for example, enable future mobile devices to download massive amounts of data, such as streaming high definition video, without draining the battery or clogging the network. Another application is to enable imaging for detection of illicit explosives or firearms, without use of any harmful radiation. These materials might even find their way into future computers to enable the doubling of computing power to continue every two years, as it has for the last forty years. Other properties of the material mean that we can make infrared sensors for thermal imaging or detection of harmful gases, or photovoltaic devices that would make much more efficient solar energy systems. A corollary of these properties is that heat can cause the materials to "leak" charge, even at room temperature, so currently the only commercial applications are in high performance thermal imaging systems, where the application can tolerate the cost of having to provide cooling to -200C to make them work. This need to cool was previously assumed to be fundamental, however Ashley and co-workers have shown that this is not necessarily the case, and that uncooled operation is possible in several applications. This research will put in place the core technology that would enable a range of devices to be made that will work without any cooling. This technology includes being able to make features on the devices that are more than one thousand times smaller than a human hair and still have the devices operating effectively. It includes the addition of "nano-antennas" to the devices to improve their sensitivity to infrared light by orders of magnitude. It also includes work to show that the devices could be integrated with silicon, to benefit from the system cost savings derived from the massive investment in the silicon industry. The successful outcome of this research would be that various industries in the UK are able to quantify the benefits that the technology offers and make decisions to develop it into products. These would include the sensor manufacturers; prospective new companies in the mobile communications field; and renewable energy community.