Unlike a patch cord—which has connectors on both ends—the bare fiber end of a pigtail is designed to be permanently spliced (either by fusion or mechanical splicing) to the incoming fiber cable in the field. 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. The most efficient way to terminate a fiber run is by using a pigtail. A fiber pigtail is a short length of optical fiber that comes with a high-quality, factory-polished connector already installed on one end, leaving a length of exposed glass on the other. This article will show you what a fiber optic pigtail is.