Applications of Holey Fibre: Splicing, Spot-size conversion and Coupling

This thesis investigates properties and applications of Holey Fibre (HF), a recent innovation in the field of optical waveguiding. HF is an all-silica optical fibre with a solid core surrounded by an array of air holes that provide a low-index cladding. The strong guidance of HF and the numerous degrees of freedom available in design give rise to novel properties, including the capability of single mode behaviour over an unprecedented range of wavelengths, and anomalous dispersion below 1.27 µm. Numerical analysis of any fibre type is important in providing a better understanding and predicting properties more cheaply and quickly than manufacturing larger quantities for testing. It is of crucial importance to HF because manufacturing remains at a prototyping stage and cannot provide the variety of HF required for experimentation over a broad range of parameters. In order to investigate longitudinally varying HF structures and nonlinear processes the finite difference time domain (FDTD) method was used to develop a new model for the study of HF's. Results obtained from this model correlated well with existing experimental and analytic results. The model was applied to provide the first investigation of splice loss between standard fibre and HF, and to optimise HF design to minimise such loss. The model also provided the first demonstration of HF for low-loss spot size conversion. A modified version of the model was used to analyse coupling effects in HF. Theoretical analysis is presented for each investigation.