Termination Procedures

Whatever you do, always follow the manufacturer's termination instructions closely . 

Multimode connectors are usually installed in the field on the cables after pulling, while singlemode connectors are usually installed by splicing a factory-made "pigtail" onto the fiber. The tolerances on singlemode terminations are much tighter than multimode and the polishing processes are more critical, so singlemode termination  is better done in a factory environment using polishing machines (right). You can install singlemode connectors in the field for low speed data networks, but you may not be able to get losses lower than 1 dB and reflectance may be a problem!

Multimode Terminations: 

Several different types of terminations are available for multimode fibers. Each version has its advantages and disadvantages, so learning more about how each works helps decide which one to use.

Singlemode Terminations: 

Singlemode fiber requires different connectors and polishing techniques that are best done in a factory environment. Consequently most SM fiber is field terminated by splicing on a factory-terminated pigtail or using pre polished/splice connectors. Singlemode termination requires special connectors with much tighter tolerances on the ferrule, especially the hole for the fiber. Polishing requires special diamond polishing film on a soft rubber pad and a polishing slurry to get low reflectance.  But you can put SM connectors on in the field if you know what you are doing. Expect  higher loss and high reflectance.    

Adhesive Terminations: 

Most connectors use epoxies or other adhesives to hold the fiber in the connector ferrule and polish the end of the fiber to a smooth finish. Follow termination procedures carefully, as they have been developed to produce the lowest loss and most reliable terminations. Use only the specified adhesives, as the fiber to ferrule bond is critical for low loss and long term reliability! We've seen people use hardware store epoxies, Crazy Glue, you name it! And they regretted doing it. Only adhesives approved by manufacturers or other distributors of connectors should be used. If the adhesive fails, not unusual when connector ferrules were made of metal, the fiber will "piston" - sticking out or pulling back into the ferrule - causing high loss and potential damage to a mated connector. 

The polishing process involves three steps which only takes a minute: "air polishing" to grind down the protruding fiber, polishing on a soft pad with the fiber held perpendicular to the polishing surface with a polishing puck and a quick final fine polish.