Analysis of splitting ratio of a symmetric directional coupler fabricated with triangular-index fibers in nonlinear condition-a design perspective

Abstract

We report here one of the significant performance parameters of a 2 × 2 symmetric directional coupler, the splitting ratio, in the nonlinear conditions considering the coupler fabricated with two similar mono-mode triangular index fibers. Different sets of physical aspects like V-number, core-radius of the fibers used, core-to-core distance of separation between the fibers in coupler structure, operating wavelength, index of refraction of the core have been considered for evaluating the splitting ratio at different lengths of fused fiber coupler. This analytical exercise is an effort for extending an indication to the optical device design engineers. This has been worked out involving the reliable mathematical instrument, the Chebyshev technique. The change of behavior of the splitting ratio in different linear and nonlinear conditions and with different physical parameters has been studied rigorously. Our theoretical analysis goes superbly with that derived using the complicated and lengthy finite element technique. This exercise needs modest computation. Hence, this report on splitting ratio analysis of 2 × 2 symmetric directional coupler composed of two mono-mode triangular- index fibers will prove its feasibility as a ready reference in the area of nonlinear photonic design engineering.