A Loss Model for Parabolic-Profile Fiber Splices

Abstract

In the past, measurement results of splice loss of optical fibers have corresponded poorly to existing theory, which assumes a uniform power distribution across the cone of radiation defined by the local numerical aperture. In this paper, a model is developed in which a Gaussian power distribution across the local numerical aperture is assumed. Transmission through a splice at each point on the transmitting core is found to depend on the ratio of receiving to transmitting numerical aperture at that point. Numerical integration of these “point” transmission functions over core areas of interest yields both splice loss and the additional loss that occurs in a long fiber following the splice. This model cannot be theoretically rigorous, since it is inconsistent with boundary conditions required by the laws of light propagation. However, it has been found to predict splice loss under varying conditions with much greater accuracy than existing theory. The model has the further virtue of being able to calculate how variations in many intrinsic and extrinsic splice parameters combine to produce an overall splice loss.