A practical model of fused fibre couplers

Describes a simple analysis of fused couplers which successfully models effects associated with the geometry of the fused device cross-section. The analysis is based upon an effective index technique, whereby geometrical features are mimicked by corresponding features in the refractive index profile of an equivalent waveguide. A brief account of the computational technique is followed by some examples of the application of the model. Particular attention is given to environmentally insensitive wavelength multiplexing couplers and the operation of asynchronous wavelength-flattened couplers