Mid-infrared (mid-IR) absorption spectroscopy is a well-known and versatile analytical technique for uniquely identifying and measuring the concentrations of gases, chemicals, and biological molecules by measuring which wavelengths of mid-IR light an analyte absorbs. Existing mid-IR absorption sensors are however either bulky and expensive (e.g. benchtop spectrometers), or have poor sensitivity and specificity (e.g. LED based sensors). Miniaturising such sensors could be transformative for diverse medical, industrial, and environmental sensing scenarios. High performance, low cost, and small spectroscopic sensors could be created using mid-IR optical circuits on silicon chips. These chips would ideally combine all of the required optical functions of the sensor (i.e. light source, waveguides for routing light, interaction between the light and the analyte, and light detection), and could be fabricated at low cost in high volumes, thanks to existing silicon manufacturing infrastructure that has been developed for electronics and for near-infrared optical communications. The last few years have seen rapid development of many of the components that are needed to create these sensor systems: silicon photonic waveguides that can transmit light with low loss at almost any mid-IR wavelength have been developed, while lasers emitting high powers in the mid-IR are now readily available and have been successfully integrated with silicon waveguides. However, there remains a crippling lack of practical photodetector technologies; those that have already been integrated wilth optical circuits on silicon chips are either expensive to manufacture, are impractical because they have to be cooled to cryogenic temperatures, or do not work at all required wavelengths. This project will develop new waveguide integrated thermal photodetectors, which work by converting the incoming light into a temperature change that can be measured with an electronic circuit. They will be able to operate at room temperature at any mid-IR wavelength, and will be manufactured using low cost techniques. This project will also demonstrate that sensors employing these photodetectors can reach the sensitivities required for clinical and industrial uses, by using them to measure low concentrations of artificial sweeteners in soft drinks - an industrially important example application. These detectors will potentially transform mid-infrared sensor systems from an academic curiosity into a commercially viable technology.

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).

This fellowship is situated at the interdisciplinary boundary of chemistry, physics and crystallography and will deliver transformative insights into the crystal structure-functional property relationships in next-generation advanced materials. Advanced functional and quantum materials are an exciting frontier in current research. They are widely studied due to the intriguing properties they host such as ferroelectricity, multiferroicity, quantum magnetism and spin liquid phases. A number of them form a major part of our daily technology, ubiquitous in applications as wide ranging as touchscreens, loudspeakers in smartphones and sensors in medical ultrasound devices. At the cutting edge of materials discovery, compounds are becoming ever more complex in structure, with new mechanisms driving their properties. To enable further targeted development and rational design, it is paramount to understand the microscopic structure-property relationships in these current materials in order to develop design pathways for the next generation of advanced materials. However, these complex materials pose two key challenges to traditional approaches to studying these - complexity and sensitivity. Their complexity makes it difficult to deduce the crystal structure with the required accuracy, even with advanced synchrotron, electron and neutron based techniques. The sensitivity of the properties to subtle details of the crystal structure as a function of e.g. chemical composition, temperature and magnetic field makes it extremely hard to correlate the (traditionally separate) determinations of structure and physical properties. Through this fellowship I will apply a transformative cross-disciplinary approach to tackle these problems, combining (i) state-of-the art neutron diffraction, (ii) targeted materials synthesis, (iii) unique in-situ physical property measurements and (iv) isotopic enrichment to unravel the highly non-trivial structure-property relationships in advanced materials. My expertise in chemistry, physics and crystallography, along with access to state-of-the-art facilities and collaborations with world-leading groups will drive this interdisciplinary research programme which will provide the foundations for tailored rational design of novel advanced materials. The focus is on two key scientific themes. The first is the exploration and discovery of crystal structure-physical property relationships in a new generation of complex ferroelectrics and multiferroics. These have wide-ranging potential applications from specialised sensors and actuators in automotive and aerospace applications to affordable, sustainable mass-market devices for consumer technology. The second research theme will concentrate on materials in which atomic-level quantum phenomena coupled with unique structural motifs give rise to novel emergent quantum phases. These include complex quantum magnetism in non-centrosymmetric materials and elusive quantum spin liquid phases.