Analysis of splice loss in single-mode fibres using a Gaussian field approximation

By using a Gaussian field approximation to the fundamental mode in a single-mode fibre, a very simple formula is derived for the splice loss in the two fibres when transverse, longitudinal and angular misalignments exist simultaneously. It is shown that the effects of the three misalignments on the splice loss are more significant for step-index fibres than for parabolic-index fibres, and also that matching oil in the gap between the fibres is effective for the end separation, but produces a reverse effect for the tilt. Calculated coupling efficiency between step-index fibres is compared with the experimental data reported so far, and good agreement between them is observed.