A general characterization of splice loss for multimode optical fibers

The Gaussian point transmission model for calculating optical fiber splice loss is extended to the general case of splice loss between fibers which differ in one or more intrinsic parameters–core radius, index of refraction profile shape, and maximum index of refraction difference between core and cladding. The model is first verified for splices with index-of-refraction, profile mismatch. The average difference between calculated and measured splice loss due to profile parameter mismatch is 0.04 dB. Comparisons are also made between calculated and measured splice loss for ten different splices with mismatch in all three intrinsic parameters. The average difference between the calculated loss and the average of several measured losses for these ten cases was 0.06 dB. The additional losses introduced by transverse offset measured for one set of mismatched fiber splices agree with the calculated values within 0.1 dB. Loss due to misalignment of elliptical core fibers is calculated and measured with agreement within 0.06 dB for the maximum toss case. Both the model and the experimental data show that, for a given percentage mismatch, index of refraction profile parameter mismatch and core ellipticity contribute significantly less to splice loss than mismatch of core radius or numerical aperture. A family of curves for splice loss vs transverse offset is presented for various numerical aperture mismatches and core radius mismatches, since these parameters are typically the largest components of splice toss in practical fiber optic systems.