Pigtails are ultimately not cold-joined

Pigtails are fiber optic cables which are only terminated on one end. The other end is open fiber, which can then be spliced into a network by mechanical or fusion splicing. 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. Optical fibers can be joined together, such that light is efficiently transferred from one fiber to another. This method is typically used for permanent connections, but it allows for disassembly without damaging the fiber ends. [pdf]