We are on the verge of a global revolution in lighting, as efficient and robust light emitting diode (LED) based 'solid state lighting' (SSL) progressively replaces traditional incandescent and even fluorescent lamps and finds its way into new areas including signage, illumination, signalling, consumer electronics, building infrastructure, displays, clothing, avionics, automotive, sub-marine applications, medical prosthetics and so on. This technology has tended to be viewed, so far, primarily as a way to improve energy- and spectral-efficiency, but what has been relatively little studied or appreciated is its profound implications for the future of communications. We envisage the tremendous prospect of an entirely new form of high bandwidth communications infrastructure to complement, enhance and in some cases supercede existing systems. This LED-based technology will utilise the visible spectrum, largely unused for communications at present and more than 10,000 broader than the entire microwave spectrum. This promises to help address the 'looming spectral crisis' in RF wireless communications and to permit deployment in situations where RF is either not applicable (e.g. in underwater applications) or undesirable (e.g. aircraft, ships, hospital surgeries), but the implications are more fundamental even than that. The key point, in our view, is that lighting, display, communications and sensing functions can be combined, leading to new concepts of 'data through illumination' and 'data through displays'. Imagine, for example, a 'smart room', where 'universal illuminators' provide high-bandwidth communications, sensors monitoring the environment and people within it, provide positioning information and display functions, and monitor the quality of the light. Imagine novel forms of personal communications system that combine display functions and video with multiple, high-bandwidth communications channels. These could be through mobile personal communicators (developments of mobile phones or personal digital assistants) or even wearable and mechanically flexible displays. Our ambitious programme seeks to explore this transformative view of communications in an imaginative and foresighted way. The vision is built on the unique capabilities of gallium nitride (GaN) optoelectronics to combine optical communications with lighting functions, and especially on the capability of the technology to implement new forms of spatial multiplexing, where individual elements in high-density arrays of LEDs provide independent communications channels, but can combine as displays. We envisage ultra-high data density - potentially Tb/s/mm2 - arrays of LEDs in compact and versatile forms, and will develop novel transceiver technology on this basis on both mechancially rigid and mechanically flexible substrates. We will explore the implications of this approach for multi-channel waveguide and free-space optical communications, establishing guidelines and fundamental assessments of performance which will be of long-term significance to this new form of communications.

The goal of this proposal is to develop advanced fabrication processes for Gallium Nitride (GaN) and related materials (AlN and InN), collectively the III-Nitrides, for the 21st Century manufacturing industries. The III-Nitrides are functional materials that underpin the emerging global solid state lighting and power electronics industries. But their properties enable far wider applications: solar energy conversion by photovoltaic effect and water splitting, water purification, sensing by photonic and piezoelectric effects and in non-linear optics. Many applications of these functions of the III-Nitrides are enhanced, even enabled by creating three dimensional (3D) nanostructures. As such, the particular focus of the proposed research is to develop and nanostructuring processes on a manufacturing scale and to unlock the potential of these properties of the III-Nitride semiconductors in a range of innovative materials and devices. The research will address and resolve 1) the need of industry to be able to scale-up laboratory-based results based on individual piece or wafer fragments to batches of wafers of up to 6 inches in diameter, 2) the need to be able to design devices that are robust with the manufacturing tolerances, and 3) the need to rapidly characterise the devices to increase packaging yield. Potential commercial exploitation of the manufacturing processes and innovative materials and devices will be aided and led by the applicants' company partners. The programme of research opens with developing the core capability of wafer-scale (up to 6 inch) nanopatterning by nanoimprint lithography and the newly developed technique of Displacement Talbot Lithography, a potentially disruptive technology for generating nanostructures. These lithographic techniques will then be integrated with additive and subtractive processes to form 3D nanostructures across whole wafers. In a major application, the developed nanofabrication techniques will be used in developing manufacturing processes for the growth by metal organic vapour phase epitaxy (MOVPE) of non-polar and semi-polar GaN templates to address the persistent problem of the quantum confined Stark effect limiting the efficiency of light emitting diodes (LEDs) and GaN based laser diodes. The computer aided design method known as Designing Centering will be developed for process optimisation to maximise the yield of nanostructured devices (initially LEDs). Another activity will be to explore the use of electron beam and optical techniques, which are capable of characterising materials and devices on the deeply sub-micron scale, as production tools for screening materials and part-processed devices. The combination of wafer-scale nanofabrication techniques, advanced MOVPE growth, characterisation methods and Design Centering will then be deployed in the design and manufacture of innovative and emerging devices including core-shell structures for LEDs and photovoltaic applications, and nano-beam sensors that incorporate photonic crystals. Having established the core capability for the III-Nitrides, it will be extended to nanostructuring other semiconductors, notably InP and related materials as used in the manufacture of devices for optical fibre telecommunications.