Control of power-splitting ratio in asymmetric fused-tapered single-mode fibre couplers

The extent of coupling in asymmetric fused-tapered single-mode fiber couplers is found to vary not only with the initial cladding diameters of the fibers to be tapered but also with the degree of fusion in the coupler. It is thus possible to optimize the coupling efficiency of dissimilar-fiber couplers by adjusting the degree of fusion without resort to etching the fibers. A simple slab-waveguide model is described that can account for these trends in coupler performance