Fusion splicing is the act of joining two optical fibers end-to-end. The goal is to fuse the two fibers together in such a way that light passing through the fibers is not scattered or reflected back by the splice, and so that the splice and the region surrounding it are almost as strong as the intact fiber. The source of heat used to melt and fuse together the two glass fibers being spliced is usually an electric arc,but can also be a laser, a gas flame, or a tungsten filament through which current is passed.