The process of joining two fibers together permanently is Fiber splicing with fusion splicer. Fusion and mechanical splicing are two fiber splicing types.

Two optical fibers are not fused together physically in Mechanical splicing, rather inside a sleeve, two fibers are held butt-to-butt with some mechanical mechanism. You will get back reflection and worse insertion loss in mechanical splices as compared to in fusion splices. For fiber testing and emergency repairs, Mechanical splicing is mostly used. 

The second type splicing is called Fusion splicing. By an electric arc, two fibers are literally welded (fused) together in fusion splicing. As it provides for virtually no back reflection and the lowest insertion loss, Fusion splicing is the most widely used splicing method. The most reliable joint between two fibers is offered by Fusion splicing. Fusion splicing is done with an automatic machine called fusion splicer.

As we said above, the machine used to weld (fuse) two optical fibers together is fusion splicer. Fusion splicing is the other name for this process. In alignment fixtures, the fiber ends are placed, cleaved, and prepared on the fusion splicer from the fiber tool kit. The fiber ends are brought together after being heated with electrodes and fused at the press of a button.

Fusion splicers are automatic machines that you need to either set the splicing parameters yourself or choose factory recommended settings.

To inspect the two cleaved fibers, Optical fiber core alignment fusion splicers use multiple cameras before fusing. Multiple axis movement of the fibers is allowed by them.

Allowing users to store separate recipes or programs, Core alignment splicers are high-end units where factors such as temperature and splice time can be customized highly. Such high end fusion splicers visually display the splice after magnifying it and, and to line up the fibers, they use active core-alignment.

Resulting in a typical splice loss of only 0.02dB, this provides for precise fiber alignment. For all single mode fiber applications, this level of precision is required and performance of multimode fiber is also enhanced. Core alignment is usually used by Ribbon splicers. The fiber cleaner is also useful.