Since there are many types of fiber optic connectors available, choosing the right one might seem confusing. To help you determine which connector would work best for you, think about these questions:
- What are your installation requirements?
- What equipment are you using?
- What type of optical fiber is being installed?
Of course you can always use an adapter, but it’s easier to determine the fiber and connector styles ahead of time to ensure proper selection. Let’s learn more about the different types of fiber optic connectors.
Fiber Optic Connector Types
As we’ve mentioned above, there are several various connectors available. The three most popular choices in the U.S for networking as well as audio/video are LC, SC and ST.
LC Connectors, or Lucent Connectors, are great for high-density installations and feature a clip design. They are smaller than SC or ST connectors; the ferrule measures 1.25mm. Very often SFP modules and fiber optic extenders require LC connectors.
SC stands for a snap-in connector. It’s a regular push-pull connector that’s larger than the LC type, measuring 2.5mm. SC connectors are most commonly used with certain styles of fiber optic extenders. It should, however, be noted that LC connectors are more common that SC ones.
ST Connectors measure 2.5mm and were designed by AT&T. They have bayonet mounts and long ferrules shaped like cylinders to hold the fiber. Ferrules can be ceramic, metal or plastic.
How to choose the right fiber optic connector
The type of the fiber being used as well as the equipment that the fiber cable will be plugged into determine the style of the connector needed. Once again, LC connectors are a popular choice in high-density installations. Additionally, they are almost exclusively used in network applications.
It’s important to remember that fiber connectors are designed with the type of fiber being used in mind. That being said, a single mode needs a 9/125 connector, while a multimode fiber requires either a 50/125 µm (OM2/OM3/OM4) or 62.5/125 (OM1) connector.
Types of polish
Now that we’ve talked about the different types of connectors, let’s focus on the various ways the endfaces are polished. After all, the polish affects the connector’s level of return loss, or back reflection.
Single mode connectors are marked as either UPC (Ultra Physical Contact) or APC (Angled Physical Contact). UPC connectors are used most often. They’re blue and have a slightly domed endface. APC connectors are green and have an 8 degree angle at the endface. They are used by service providers and only with specific applications or long distance transmissions.
Since these endfaces are very different, they cannot be used interchangeably. It’s necessary to verify which connector – UPC or APC – is required for proper installation.
To help you identify them and distinguish between multimode and single mode APR or UPC, connectors are often color-coded. The colors may vary between manufacturers, so it’s always important to double check cables and connectors. General guidelines, however, are as follows:
- Blue: single mode UPC
- Green: single mode APC
- Aqua: 50/125 Multimode (OM3/OM4, compatible with OM2 fibers as well)
- Beige (variable): 62.5/125 Multimode (OM1)
- Black: 50/125 Multimode OM2 (varies by manufacturer)
As you’re getting ready to get the right fiber optic connector, make sure you consider several factors. Do you need an LC, SC, or ST connector? Is a single-mode or a multimode fiber being installed? If it’s a multi-mode, what grade is it (OM2/OM3/OM4)? If it’s a single mode fiber, check for any special indications (like APC). If there aren’t any, UPC connectors (blue) are considered to be default.