A New Formulation Of The Coupling Coefficient For The Fused Fiber Optical WDM Couplers

The fused fiber optical WDM couplers have been widely used in optical communications industry. A new formulation of the coupling coefficient for these kinds of couplers is proposed in the paper. The new coupling coefficient formula is based on the unique combination of those of two models:weakly fused coupling model and strongly fused coupling model. The wavelength channel spacing of the WDM at different pulling stop cycles based on the new formula is then calculated and compared to the experimental results obtained by using the industrial-standard coupler making machine. Good agreements in the channel spacing from400nm down to40nm are achieved. The two parameters which are introduced in the new formulation are found directly related to manufacturing parameters:hydrogen gas flow rate and pulling speed. These new relations can provide direct guidance for the optimized fabrication of the fused fiber optical WDM couplers.