This FC pigtail is a multimode cable with high-grade FC UPC fiber optic connector on one end, another end unterminated. A fiber optic pigtail is a short length of optical fiber —typically 0. The connector end is polished and tested under factory conditions, ensuring low insertion loss and high return loss. 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. A fiber optic pigtail is a short optical fiber cable that has a connector on one end and an exposed (unterminated) fiber on the other. The connector end plugs into devices like transceivers or patch panels, while the bare end is typically fusion spliced to a fiber optic cable.