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.

Modal Analysis of Loss and Mode Mixing in Multimode Parabolic Index Splices

“…Uniform-power distribution results do not agree with realistic splice loss measurements," Figure 2 demonstrates 1088 versus transverse offset for several power distributions, the Gaussian splice 1088 model, 2 and experimental data," The experimental data shown were obtained using 0.82-p.m laser excitation of a 7-km input fiber containing about 14 splices into a final splice that was offset in both x andy orthogonal axes. The offset data are in good agreement with previous data and should represent a realistic "steady-state" condition.…”

“…(1) can still be expressed byeq. (2) for both fibers. However, the radial and azimuthal variations of the receiving fiber (rR, q,R) need to be expressed in terms of the transmitting fiber (rT, q,) and the transverse offset, r», of the axes.…”

A General Characterization of Splice Loss for Multimode Optical Fibers

“…2 This model assumes that a steady-state power distribution (after a long length of fiber) can be modeled as a Gaussian distribution of the power within the solid angle defined by the local numerical aperture, NA, at any point on the fiber core ( Fig. 1).…”

“…The development of a phenomenological Gaussian point loss model 2 allows an approximate analytic treatment of the loss induced by a butt-joint splice between fibers which differ in one or more intrinsic parameters. Previous models based on the uniform power distribution assumption 1 have exhibited only limited agreement between calculated and measured splice loss, 3,4 whereas the Gaussian model gives good agreement with experimental data.…”

Split-spectrum intensity-based optical fiber sensors for measurement of microdisplacement, strain, and pressure

“…A number of simplified analytical models for evaluation of the excess loss of step-index multimode fiber splices have been proposed in the past. [9][10][11] However, because of the complexity of the MPD, only two specific MPD's, namely a uniform MPD and a steady or equilibrium MPD, typically are considered in these models. The model in which a uniform MPD is assumed has a very simple expression.…”