Ultra-parallel visible light communications

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.

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