Fusion Splicer Termination: Fiber optic pigtails are used in fusion splicing, a process that involves permanently joining two optical fibers together. Get the wrong connector type, the wrong polish, or skip proper fusion splicing technique—and you're looking at elevated signal loss, increased back reflection, and a. Fiber pigtails are simple in appearance, yet essential in function. By combining factory-installed connectors with spliced bare fiber, pigtails ensure that network installers can create. The fiber optic pigtail is a type of fiber optic cable with a pre-installed connector on one end while the other remains unterminated.