Direct and inverse design of microstructured optical fibres
Microstructured optical fibres, where an arrangement of air holes running longitudinally along the fibre guides light in either a solid or a hollow core, have created new opportunities in diverse areas of science and technology. Applications range from the generation of supercontinuum light to optical sensing, nonlinear telecom devices and the generation and delivery of extremely high optical powers. Photonic bandgap fibres, allowing light guidance in a hollow core, are also extensively studied. The main issues preventing accurate simulations of the properties of fabricated fibres are identified and addressed. An ideal, accurate representation of a realistic fibre is then proposed and employed to obtain fundamental scaling rules and to study the interactions between air guided and surface guided modes. Anticrossings between these modes in slightly asymmetric structures are identified as the cause for the unusual polarisation effects experimentally observed in these fibres. And finally, guidelines for fabricating fibres with the widest possible operational bandwidth possible are developed and presented.