The material presented in this thesis is based on some of the research work I have conducted since I completed my PhD in 2006. The totality of this research work takes the form of 41 technical papers that are cited in the References section. These papers are both conference proceedings and journal papers as well as several book chapters. Naturally the work of a great many researchers the world over and over many generations have contributed to a very broad literature in optics, which are liberally cited in my own publications but are not cited in this thesis. Here I have decided to emphasise my own contributions to the field. All of the arguments I make in this thesis are based on conclusions and insights from my own research work and hence it is only that work which I reference. I hope that the interested reader will understand my motivation for this unusual approach and can find extra supporting material in my own papers.