An Analytic Connector Loss Model for Step-Index Polymer Optical Fiber Links

The authors report on an analytic connector loss model for step-index polymer optical fibers (SI-POF). The model describes the non-linear dependencies for combinations of the most important intrinsic and extrinsic influence parameters like Fresnel reflections, mismatches in numerical aperture (NA) and core diameters, as well as lateral, longitudinal and angular offsets. As connector losses strongly depend on the mode distribution, expressions for the mode-dependent coupling efficiencies for the various influence parameters are derived. This way, the model can handle any rotationally symmetric mode distribution including the uniform mode distribution (UMD) and the equilibrium mode distribution (EMD) in the steady-state. It is shown that for step-index fibers, lateral and longitudinal offsets can be handled in a similar way, which reduces the overall effort for the mathematical description. For the typical case of identical fibers, the authors also derive easy-to-apply approximations for a combination of lateral and longitudinal offsets under UMD and EMD conditions. The results are in good agreement with ray-tracing simulations and are evaluated for the cases of identical fibers and the worst case parameter constellation for the SI-POF in the IEC A4a.2 fiber class.