Optical vortices in nonlocal nonlinear media

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The use of light to transmit signals in telecommunication systems is now ubiquitous and, indeed, the telecommunications system would collapse without the use of laser light in optical fibres for transmission. A major drawback to fully utilising the vastly increased capacity opportunites presented by using light in telecommunication systems is that there are still no optical equivalents for most of the electronic devices used to process signals. This lack of optical equivalents presents a bottleneck in the telecommunication network in that electrical processing is slower than optical processing, in part due to the need to switch between opticsl to electrical, then back to optical signals. A major scientific and engineering problem is then to design optical equivalents to electrical signal processing devices. The present proposal deals with one such problem, the design of re-configurable circuits using so-called optical vortices. Optical vortices can form channels through which optical signals (solitons) can propagate. As these vortices can be formed anywhere and in any direction in an optical material, they then can be used as the equivalent of eletrical wires which can be changed at will. Before such optical vortices can be used, fundamental questions need to be addressed, such as for which parameter values and configurations are such optical vortices stable? How do such vortices evolve when they are perturbed? How easily can they be generated in the laboratory? It is known that for many materials, optical vortices are unstable due to these materials not having long range interactions. So what is needed is materials which possess long range interactions. One such material is a liquid crystal. It is then proposed to investigate the stability and evolution of optical vortices in liquid crystals as an example of such evolution in a non-local material. The results of this research will then be used to form and study optical vortices in the laboratory.