Estimation of Coupling Power Parameters of 1X3 Directional Fused Fiber Couplers

The coupling characteristics of 1X3 directional fiber coupler are reported. Power distribution in coupling region has been calculated by using Transfer Matrix Method (TMM) based on coupling mode theory. It has shown that if the three fibers are electro magnetically isolated, propagation constant, and separation between the fibers are maintained constant, power distribution among three fibers are periodically normalized. By launching 1mW input power to the fiber 1, it will be transferred gradually to the fiber two then fiber three. Although, the input power will be symmetrically distributed to the two others fiber by launching power to the center fiber 2. However, the power exchange between the fibers in coupling region significantly depends on the coupling length and coupling coefficient between them. It has been shown in 3D that the coupling coefficient describes how strong the coupling can transfer its power to the others. It is found, the higher coupling coefficient, the shorter coupling length is required to transfer power.