Effect of asymmetric refractive-index profile on skew in single-mode fiber ribbons

Low cost fiber ribbons with small skew value must be realized for high bitrate parallel optical transmission systems. The influence of asymmetric refractive-index profile is precisely investigated for this purpose. The previously proposed variational analysis can deal with the asymmetric profile. The accuracy of this analysis is checked theoretically and experimentally. The calculated skew values by the variational analysis are compared with ones by vector analysis using a multilayer approximation for symmetric profiles. The calculated values by the variational analysis are compared with the experimental data for asymmetric profiles. Considering the clarified accuracy of the analysis, skews of several asymmetric profiles are calculated. By measuring skew values of commercially available fiber ribbons, realization of low cost, small skew fiber ribbons is discussed.