Analytical expression for measurement of intrinsic coupling loss in multistep index optical fibers

The aim of this paper is to obtain an analytical expression for intrinsic coupling losses in multistep index (MSI) fibers. For this purpose, a uniform power distribution is assumed. In order to validate the theoretical expression, the obtained results were compared with computer simulations using the ray-tracing method as well as with results obtained using existing models for step index (SI) and clad power-law profile graded index (GI) fibers. This analytical expression will provide fiber manufacturers with a very valuable tool for the assessment of fiber quality in terms of waveguide tolerances