2 X 2 fused fiber evanescenttype couplers are analysed for distributed coupling depending on arc temperature profile. During fusion core-to-core fiber spacing and hence coupling coefficient between the two fibers varies along the interaction length. The analysis is based on the surface tensile and viscous force equilibrium during fusion. Arc current determines a particular temperature profile. Functional dependance of coupling coefficient c(z) on position z along the coupling length is derived for various arc currents. A theoretical model is developed to analysis the coupling for 2 x 2 and twin-core single -mode(SM) fiber couplers. Effective interaction length determined by arc currents and number of arcstrokes is calculated. Coupled power is finetuned by controlling initial clad thickness arc current and fusion time. The excess loss and devia tion for 2 x 2 SM fiber coupler are0. 12 and0. 04 dB respectively. The strength becomes maximum for a fusion time of 2. 5 sec. N x N couplers are proposed finally. Preservation of cores and their finite separation in a single plane reduces loss deviation and nearly preserves the state-of-polarization (SOP) of the input signal.