fluorine-doped or titanium coated) may cause white or black lines in splice region that are not faults. Splicing is required to create a continuous path for light transmission from one fiber to another. Two different methods exist for splicing fibers: Typical splice loss values (the measure of loss in optical power across the splice point) are usually lower for fusion splices (typically less than 0. Multimode fibers can be harder to fusion splice as the larger core with many layers of glass that produces the graded-index profile are sometimes harder to match up, especially with fibers of different types or manufacturers.