Photonic crystals in planar waveguides
In this thesis the properties of waveguide modes in photonic crystal planar waveguides are considered. These are waveguides that have been etched with multi-dimensional gratings to create new wavelength dispersive and spatially dispersive behaviours. Analytical models have been developed for the modes in one and two-dimensional photonic crystal waveguides. These describe many of the rich phenomena that may be observed. Weak two-dimensional photonic crystal planar waveguides have been fabricated and their properties have been measured with a specially developed conical prism coupling technique. This thesis demonstrates the advantages of combining photonic crystals with planar waveguides. While future lithographic systems will have sufficient resolution to incorporate photonic crystal regions in integrated optical devices, it has been shown that the waveguide geometry increases the actual grating period required for optical band gaps and so lessens technological difficulties. It is also shown that there are stationary modes which could act as microresonators and that ranges of modes can be suppressed in multimode waveguides. Prism coupling has demonstrated the strong dispersive and frequency selective behaviour of weak photonic crystal waveguides. The future application of this work to efficient, broadband, nonlinear wavelength conversion is proposed.