Optical fibre facets: a vector analysis

A full vector, semi-analytical, yet accurate, analysis of coated optical fibre facets is presented, based upon the free space radiation mode method. This yields a simple final expression for the modal reflectivity. A highly efficient algorithm has been developed to implement this analysis. Example results for the reflectivity of the fundamental HE11 mode supported by typical single-mode fibres are given, which are compared to those obtained from an equivalent scalar investigation. Results show that correct modelling of the low reflectivities of coated facets requires a full vector analysis.