Choosing Fiber Connectors

At first, the question of fiber and connector type can seem very confusing. Think of it this way: when working with RG6 coax you can terminate with an F connector, RCA, or BNC, for example, based on what type of connectors the electronics you are working with offer. When terminating fiber, the two most common styles of connectors are SC or LC. The equipment you are hooking up to will determine the type of connector. Adapters are available, but it is always easiest to determine both fiber type and connector style ahead of time.

There are quite a few different styles of connectors. In the audio/video industry, the three most popular styles are SC, LC, and ST.

  • SC: A 2.5mm snap-in connector widely used in single mode systems for its excellent performance and in multimode systems because it was the first connector chosen as the standard for TIA-568. It is a snap-in connector that latches with a simple push-pull motion. It is also available in a duplex configuration.
  • LC: A Lucent connector uses a 1.25mm ferrule, half the size of the ST and SC. Otherwise,it is a standard ceramic ferrule connector, favored for single mode. It is also the connector of choice for multimode transceivers gigabit speeds and above.
  • ST: A 2.5mm AT&T™-designed connector for single mode and multimode networks. It has a bayonet mount and a long cylindrical ferrule to hold the fiber. Most ferrules are ceramic, but some are metal or plastic.

Connector style is determined by the equipment that the fiber cable will be plugged into. Many people will standardize on SC connectors due to their lower cost and ease of use. If you know what equipment you will be using, you will be able to determine which style of connector to install up front.

Connectors are available from many manufacturers. They are designed specifically for the type of fiber you are using. Single mode uses a 9/125 connector, and multimode utilizes a 62.5/125 (older technology) or 50/125 connector.

There are actually multiple types of connection methods for fiber optic cables. The most common for inside premise and in the audio/video world are mechanical splice connectors.

  • Mechanical Splice: Connectors with a short stub of fiber already epoxied into the ferrule and polished, along with a mechanical splice in the back of the connector. Simply cleave a fiber and insert it like a splice. This process can be completed very quickly. Cleerline SSF™ connectors are all mechanical splice.
  • “Hot Melt” Adhesive/Polish: This is a 3M™ trade name for a connector that already has the epoxy (actually a heat set glue) inside the connector. Insert the connector in a special oven. The glue quickly melts, allowing you to remove the connector and insert the stripped fiber. Let it cool, and it is ready to polish
  • Anaerobic Adhesive/Polish: These connectors use a quick setting “anaerobic” adhesive to replace the epoxy or Hot Melt adhesive. Anaerobic adhesive cures faster than other types of adhesives.
  • Crimp/Epoxy/Polish: Fiber is affixed into the connector using epoxy or by mechanically crimping. The end is polished with special polishing film by hand or with a mechanical tool.
  • Fusion: Fusion splicing is widely used as it provides the lowest loss and least reflectance, as well as providing the strongest and most reliable joint.

If you have a SC-style connector installed and find that you need LC instead, you can purchase a SC-SC coupler, then purchase a pre-terminated patch cable with SC on one end and LC on the other. This is a very common solution. Patch cables can be purchased with all various configurations (SC-SC, SC-LC, SC-ST, etc). Again, the type of equipment you are installing will determine your connector needs. There are also various adapters and patch cable configurations that can be utilized to connect fiber optic based equipment.