Causes include poor fusion splicing, misalignment of fiber cores, excessive cleave angle, or contamination in the splice. Re-splice the fiber if necessary and ensure proper alignment and cleanliness before fusing. The guide provides the complete workflow, covering safety precautions, tool selection, fiber preparation, fusion operation, quality control, and. The performance of a fiber optic splice is determined by a number of factors, including the quality of the fiber, the cleanliness of the splice, and the techniques used to make the splice. Intrinsic factors, such as the refractive index of the fiber, are those that are inherent to the fiber itself.