Analysis of fiber directional couplers and coupler half-blocks using a new simple model for single-mode fibers

A model for a step-index fiber in the form of an equivalent slab guiding structure is presented. This model simplifies the analysis of fiber directional couplers and coupler half-blocks with dielectric and metallic superstrates. Simple empirical formulas to obtain the model parameters are also given. The use of this model is illustrated with some numerical examples.>