Fiber Optic Connector Assembling – Ferrule

Most popular fibre optic connectors being used today possess some common elements. The most critical part, where the fiber is mounted, is the ferrule. Ferrule can be a long, thin cylinder using the fiber mounted in the center hole. The center hole is sized to match fiber’s cladding diameter which can be usually 125um.

The ferrule is mounted inside the connector body and therefore the connector body is attached to the fiber optic cable structure. Finally, a strain-relief rubber boot protects the connector-cable junction. Its job is always to center and align the fiber and protect it from mechanical damage. No more fiber reaches no more the ferrule, where the fiber end is polished smooth either flat or using a curvature. Fiber connector ferrules are made from several kinds of materials including ceramic(Zirconia), stainless steel and plastic.

Unlike most electronic connectors, fiber optic connectors normally do not have the male-female polarity. Most fiber connectors are male only. Instead, fiber connectors mate together in fiber adapters, which are often called mating sleeves or coupling receptacles. Fiber optic adapters used to mate different connector types, such as a FC connector to some SC connector are known as hybrid adapters, plus a bare fiber adapter will be the medium to link the bare fiber to fiber optic equipment.

Although this approach necessitates the use of separate adapters, it otherwise reduces fiber connector inventory requirements since you now need to stock one type of connector only. An additional is that fiber adapters could be made to mate one kind of connector to another, which is a big plus when compared with electronic connectors.

The fiber’s plastic coating is stripped first prior to the fiber is inserted in the ferrule. The middle hole with the ferrule is big enough to match the fiber cladding (that is usually 125um after fiber coating stripped off) but tight enough to keep the fiber in a fixed position without any further moving.

Standard bore diameters are 126 1/-0 um for single mode connectors and 127 2/-0 um for multimode connectors. As a result of fiber cladding diameter’s variation from manufacturing, some fiber connector manufacturers also supply a selection of ferrule bore sizes for example 124um, 125um, 126um and 127um.

Fiber optic epoxy or adhesive is injected in to the ferrule hole ahead of the fiber is pushed directly into hold the fiber in place. The epoxy or adhesive is then cured rich in temperature oven based on adhesive manufacturers’ instruction. Finally the fiber end is polished to some smooth face on polishing films.

The ferrule is then slipped inside another hollow cylinder before it is mounted inside the connector body. The connector body includes more than one pieces that are assembled to carry the cable and fiber in place. Connector person is made of metal or plastic.

The ferrule end protrudes beyond the connector body so that it can slip into the mating sleeves (fiber adapters). A stain-relief rubber boot is finally slipped within the cable end from the connector to protect the cable-connector junction point.

In fiber optic cross connect boxes or fiber patch panels, a range of connector adpators are mounted inside, ready so that you can plug a port fiber cable in a single side as well as an output cable in the other. Fiber connector adapters may also be mounted in wall outlets, just like standard phone jacket.

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