The ferrule is a rigid tube used to confine and support the stripped end of a fiber as found in connectors.
The ferrule, usually made of metal or ceramic, is the central part of the male connector. It is designed to both align and protect the fiber Core during connection. The ferrule tip is polished to ensure a smooth finish on the fiber end. Polish can also minimize Connector Loss or backreflection, depending on the angle used.
There are four types of polish: PC, super PC (SPC), ultra PC (UPC) and angled PC (APC).
A ferrule is a long cylinder mounted on the end of the fiber and acts as a fiber alignment tool to ensure proper fiber optic connections to either another Cable or to a Transmitter or receiver. Ferrules can be made of glass, metal, plastic or ceramic.
The ferrule keeps the fibers accurately aligned within the connector. Ceramic is the best material because it bonds well to Glass and its expansion coefficient is close to that of the glass fibers, making it environmentally stable.