Fiber Connector Types
Updated: Jan 3
When installing a fiber optic cable, choosing the most appropriate fiber connector type is crucial. This blog post will provide an overview of the most common fiber connector types, highlighting their pros and cons to help you make an informed decision. A fiber connector, also known as a termination, allows you to easily connect and disconnect fiber cables. Many fiber connector types feature a spring-loaded connection that maintains a constant force between the two fibers, ensuring a strong and reliable connection. These spring-loaded connections also eliminate air gaps between the connectors, which can impair light transmission.
Typically, there are three main components to the construction of a connector.
Ferrules are most commonly made of a material called zirconia. In the early days of connector manufacturing, the ferrules were constructed of stainless steel. Zirconia offers lots of advantages over other materials such as:
Free from cracks, chips, or imperfections
Because the grain is smaller on Zirconia, it will have a smoother finish
The thermal expansion coefficient is very close to that of fiber
A very high-impact resistance
A high modulus of elasticity
TODAY, WE WILL GO OVER THE ST, FC, SC, AND LC STYLES. WE WILL ALSO TOUCH UPON THE MTP/MPO CONNECTIONS.
ST FIBER CONNECTOR TYPES These connectors use a 2.5mm ferrule that is mounted on the inside of the housing. This is an older style connector but is still commonly used in multimode applications.
The ST connector, while older, is still commonly in use in today’s fiber installations due to it being extremely easy to install and its relatively low cost compared to some other connectors. This connector has a keyed “slot” on the end of the connector that helps keep it tightly mated to the fibers and in alignment when they are decoupled and recoupled.
ST Connectors have a round shape to them and are not as compact as more modern square-body connections. Also, with this being a spring-loaded connection, the installers must push the connector with quite a bit of force and turn the nut to use these connectors. If there is a tray with lots of connections this can get tedious as it may become hard to get into the tight spaces to decouple/recouple the connectors.
SC FIBER CONNECTOR TYPES
The SC connector was invented to directly replace the ST connectors and, as a result, has become one of the most common fiber connectors in the world. Similar to the ST connector, this SC style also utilizes a 2.5mm ferrule.
The SC connector is what is called a non-optical disconnect connector. This term means that once the connector has been installed, any pushing or pulling on the jacket of the cable will not cause the ferrule to disconnect, which is a prevalent problem with the ST model connectors. This ensures that the signal is not to be interrupted. Sometimes with the ST connectors, when they are pulled back, the spring mechanism will slam the fibers together. An SC connector can alleviate these problems.
The square shape of these connectors offers a more compact design which in turn means that more of these connectors can be installed in a smaller footprint of space. Sometimes there just is not enough room for the pull and twist connectors and that is where the SC connector becomes a lifesaver.
SC connectors are ideally suited for datacoms and telecoms.
The main disadvantage of an SC connector is that although its square body is easier to insert/take out, the body is larger than the LC connector which means it will take up more room than its newer cousin.
FC FIBER CONNECTOR TYPES
The FC connector also utilizes a 2.5mm ferrule. This connector shares a round profile like the ST connectors we reviewed but instead of coming equipped with a spring-loaded twist lock mechanism, this connector has a threaded connection.
Like the SC connector, the FC connector also has a non-optical disconnect advantage. Because this connector threads onto a connection, you can be sure that this connector will stay stable and mated to its connection, even during rougher environments.
Very similar to the ST, this connector can be hard to grab and twist to thread or unthread from a connection if there are lots of connectors in one receptacle.
LC FIBER CONNECTOR TYPES
LC Connectors were invented by Lucent Technologies (hence the LC name). This is a member of what is referred to as the small form factor (SFF) line of connectors. These SFF connectors were initially invented to fill a need for large fiber count applications. In some installations, there are dozens of connectors being plugged in and these connectors make life much easier. The LC connector uses a 1.2mm ferrule and has about half the footprint size of the other connectors we have reviewed. It does share the same non-optical disconnect as the SC and FC share. If for some reason you are looking to switch from an SC, ST, or FC connector there are some tools and adapters that can be used. Another plus for this connector is that the LC duplex connections have the same footprint as RJ45 connectors.
You can quickly convert these instruments from a simplex connector to a duplex connector with the use of a clip. They are low-loss connectors and are also pull-proof. LC connectors can quickly be terminated and have a couple of different methods to achieve that. The SFF design makes this the perfect connection for a high-density application, which is why this is the connection of choice for networking and transceivers.
The SFF design makes it hard to grasp as it is so tiny and often in a densely populated application. There are LC extraction tools that can help with this. It is probably a good idea to order an extraction tool when ordering this type of connector.
MTP/MPO FIBER CONNECTOR TYPES
These connectors are used for ribbon cables. In single-mode use, these will typically get about .25dB loss and about .20dB loss in multi-mode. These are also available in the smaller 8-fiber connectors in this configuration. Single-mode ferrules are angled at 8°. This is primarily used in very high-density applications with a ribbon cable to reduce the connector space that may be required.
MTP connectors are usually considered a high-performance option while MPO are better for mechanical uses.
MTP connectors are equipped with a housing that is removable so you can change, re-polish, or even change the gender of the connection from male to female.
MPO/MTP connectors combine 8, 12, or 24 fibers into one single and compact interface. They can put this amount of cable in the same space an SC connector would take up. This very effectively saves rack space on a high-density rack.
An MPO/MTP connector is not the easiest to clean because there are so many fibers in one connection.