APC Connector is a type of fiber connector that minimizes backreflection due to a 5° to 15° angle-polish applied to end faces. Like illustrated in the following picture. Because of the angle, the reflected light does not stay in the fiber core but instead leaks out into the cladding. What are SC/APC, LC/UPC? You may have heard. PC, UPC and APC are the three ways to grind the inner collar of a fiber optic connector (as shown in the figure below). When the. As we know, physical contact is most important to ensure low IL and high RL for fiber connection. All the endfaces are spherically polished. Understanding fiber connector types—SC/APC, SC/PC, LC/UPC, LC/APC, ST/PC, FC/PC, and FC/APC—is essential for selecting the right interface for your application.