Interferometric examination of spliced optical fibers

We used a Zeiss-Linnik interferometer to obtain interferograms of fusion-spliced optical fibers. A common feature is the presence of buckling of the fiber material on both sides of the splicing point. This resulted from the fusion splicing process. Their heights ranged from 1 to 10 μm, some 300 μm apart for graded-index optical waveguides of 50-μm core and 125-μm clad diameters. Few cases showed the presence of buckling 140 μm from the point of fusion splicing. The power loss resulting from fusion splicing for the specimens examined interferometrically was measured. It is found that the greater the buckling, the greater the power loss. A height of 2λ or less (λ = 535 nm) gave no detectable loss.