In a fiber optic adapter, the internal ferrule sleeve holds the fiber in place and aligns the filament of one fiber ferrule with its mate. The ferrule sleeve is the most expensive component to manufacture in a fiber optic adapter, accounting for approximately 80% of the total adapter cost.

The ferrule alignment sleeves are also the most critical part of a fiber optic connection process. They provide the bridge between one cable’s ferrule and another cable’s ferrule interface. The precision of the ferrule sleeve and its hole determines how well the fibers align, which affects the light signal transmission.

Fiber optic adapters are generally made with ceramic or metal ferrule sleeves. Some adapters also feature ferrule sleeves that are a combination of these materials.

Ceramic ferrule sleeves are more precisely molded and fit close to the fiber ferrule. This precise molding gives the fiber optic connection a lower optical loss. As a general rule, use ceramic ferrule sleeves for critical network connections, such as backbone runs in highly secure networks or for connections that will be changed frequently, like those in wiring closets. Ceramic ferrule sleeves best suit single-mode cable connections.

Ferrule sleeves made of metal, such as bronze ferrules, offer more durability than ceramic sleeves, but they may not offer the same precision alignment as ceramic ferrule sleeves. Drilling an accurate hole through the metal ferrule sleeve can be difficult, and that can result in less accurate fiber alignment. The use of watch-jeweled centering improves alignment. But overall, metal ferrule sleeves are better suited for multimode fiber applications where absolute alignment isn’t crucial.