Fusion splicing is the most widely used method of splicing as it provides for the lowest loss and least reflectance, as well as providing the strongest and most reliable joint between two fibers. Virtually all singlemode splices are fusion. 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. The splice is necessary to create a continuous path for light signals to travel through, but it's not always perfect. The estimate, called a "loss budget" is calculated using typical component losses for. Fiber splicing means joining two optical fibers (permanently or temporarily) such that light guided in one fiber and reaching the joint (splice) can be transferred into the second fiber with low insertion loss.
[PDF Version]