Fiber Optic Connectors

Fiber optic connectors position fiber ends to receive or transmit light. The surfaces must be smooth and perpendicular to the fiber axis for greatest efficiency in accepting light rays. Rough, slanted or dirty end surfaces block and scatter light.

Because glue-and-polish connectors are widely used, the following discussion of cable termination procedures will be based on using this type of connector.

Termination Procedure

The first step in the termination procedure is to slide the heat-shrink tubing and connector retaining assembly over the cable jacket. Then, cable materials may be stripped to the appropriate lengths-- as specified by the connector manufacturer. The cable is now ready for termination.

Most glue-and-polish systems use two-part epoxy to fasten fibers into ferrules. Setting time can range from 5 minutes to 24 hours. Five-minute epoxies are useful for fast installation in non-critical environments. Longer setting epoxies are better suited for applications where fiber strain and temperature extremes are major concerns.

Heat setting epoxies are useful for situations where many connectors are to be attached. Since these epoxies set only when heat is applied, the need for mixing separate batches is often eliminated.

Before ferrules are filled with epoxy, a trial insertion of fiber should be made. Coating residue on the fiber, or a clogged ferrule may prevent insertion. detecting such problems at this stage will help save time and ferrules.

Apart from polishing, the most critical part of connector installation is cementing the fiber securely in the ferrule. If the fiber is not evenly glued on all sides, it may crack below the end surface. See connector manufacturer instructions for recommendation of quantity of adhesive to be used.

To provide strain relief, the connector retaining assembly is crimped over the aramid strength material. This type of strain relief can typically withstand pulling tension of up to 50 Ibs.