A Light Modulator Technology for Spatio-Temporal Coherence Control

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The spatio-temporal coherence characteristics of a light source are of critical importance in a range of applications including:1) The formation of microscopic images in high-resolution imaging systems;2) The propagation of signals through atmospheric turbulent conditions in free-space optical communications;3) The quality of images generated in projection and augmented reality/virtual reality displays;4) Beam propagation in laser manufacturing and material processing;5) Optical Trapping;6) Imaging through turbulent media;7) Holography;8) Optical trapping; and9) Non-line of sight imaging - 'seeing around corners'. For many applications it would be advantageous if one could exert a level of control over the spatio-temporal coherence characteristics of the light source in a programmable way so that it could be precisely tailored to any of the applications outlined above. Conventional laser sources typically exhibit a high level of coherence. However, depending on the application, high spatial and/or temporal coherence is not always desirable. Even though it is possible to control the spatial and temporal coherence of incoherent light sources through spatial or spectral filtering, they are still fundamentally different from a laser which exhibits poissonian photon statistics, rather than Bose-Einstein photon statistics. Furthermore, for many of the applications listed above, incoherent sources are either not suitable or they exhibit other properties, such as reduced spectral control and poorer collection efficiency, which makes them unattractive.A rudimentary level of control of the spatio-temporal characteristics can be achieved using off-the-shelf technologies, but these tend to be less than ideal as they involve mechanically-moving components, are not scalable, and offer limited control of the degree of coherence. In general, they do not provide analogue control nor are they compatible with a pixelated device architecture, which would enable precise control of the coherence across the beam. To truly revolutionise the applications described above, and to take full advantage of the benefits of partial-coherence, an as-yet-unrealised level control of the spatio-temporal characteristics is required. The development of a disruptive new technology that would offer fine control of the spatio-temporal characteristics would be an extremely exciting prospect for both academic researchers and industrialists working in the fields of biomedical imaging, communications, AR/VR projection displays, and 3d laser manufacturing. Moreover, as a disruptive new technology it would have considerable impact both in terms of enabling new scientific discoveries in applied optics as well as promoting technological breakthroughs in biomedical, display, and communication engineering. The key objective of this proposal to develop a new photonics technology that would offer unprecedented control of the spatio-temporal characteristics of a laser source. This new technology will be designed and developed to be readily deployable in a range of applications, and it will be electrically addressable and pixelated so that the coherence properties can be altered independently across the light beam, leading to radically new behaviour and characteristics. The technology will be based upon electrically-responsive soft matter. The research proposed herein offers a unique opportunity to create a disruptive world-leading coherence modulator technology that could have far-reaching impact both scientifically and commercially in applications ranging from imaging to free-space visible communications. A secondary benefit of this project is that the development of this transformative technology would provide us with an exceptionally powerful tool with which to study the properties of optical coherence.