An APC connector is a fiber optic connector whose ferrule end-face is polished at an 8-degree angle, rather than flat. Either of them is physical contact fiber connectors. Angle-polished. The singlemode fiber connectors you likely encounter the most feature a blue connector body, but if you're working with any passive optical networks (PONs), carrier networks or large cloud/colo or hyperscale data centers, you may encounter singlemode fiber connectors with a green connector body –. PC, UPC and APC are the three ways to grind the inner collar of a fiber optic connector (as shown in the figure below).