Fiber Optics Explained Connectors


    Now that we are more familiar with our fiber optic cables, we come to the important bits at either end - the connectors. Connectors serve to form active connection points between transmitters, receivers, and can even link optical lines to one another with the use of a coupler. As the name implies, connectors connect fiber optic cable to their assigned devices. That being said, a variety of connector types do exist but they all serve the same purpose and are all ultimately designed to minimize signal loss in their connection by maintaining physical contact of fiber ends and to protect fiber from mechanical and environmental harm. Most signal loss in fiber optic connections results from inexact end-to-end fiber mating, or faulty connection points, so it is important to have a basic understanding of your connectors and how to use them.


The Body of a Connector

While there are a wide variety of connector types around (see below), all connectors share these 3 common components:

1.Boot- a small rubber sleeve that hugs the cable and fits onto the connector itself, providing strain relief at this junction.


2.Body- the main plastic or metal component of the connector that provides mechanical attachment via push/pull (SC and LC), threaded (FC), or bayonet (ST) coupling mechanisms.


3.Ferrule- the direct physical housing and stabilizer of the optical fiber. Ferrules are usually made of hardened materials such ceramic, stainless steel, or tungsten carbide. Because the ferrule is the agent actually holding your sensitive fiber it is extremely important to keep them well protected and consistantly clean! Standard size (ST, FC, SC) ferrule are 2.5mm in diameter while small form factor (LC) ferrules are 1.25mm in diameter.


Connector Types

    LC (Lucent Connector)- Nicknamed the “little connector”, though properly identified as the Lucent Connector, LC connections were developed specifically to take up less space in patch panels and do so effectively.  In fact a duplex LC connector takes up the same space as a simplex SC connector. The LC offers an external clip/latch mechanism which has become a popular choice in part due to its typically low signal loss and small form factor. 

    SC (Subscriber Connector)- SC Connectors have become somewhat of a standard in the fiber optic world, being greatly appreciated and known for their durability, simplicity, and low cost. The SC connector design features a push/pull connector type, which means the end face, or ferrule, is housed when not in use and therefore protected at these times. SC connectors are color-coded beige for multimode and blue or green for single-mode.

    ST (Straight Tip) or Bayonet - The ST is a forerunner of fiber optic networking connection types and in its earlier days was easily the most widely used connecter. You may see ST’s referred to as bayonets, a moniker derived from their bayonet style twist-on/twist-off connections, which provide a sturdy and reliable connection once in place. ST’s remain in wide use today and provide excellent connections provided they are carefully connected- due to their spring loaded bayonet it is possible to experience light loss from an improperly inserted ST, so be sure to align your ST connector before locking it in for use.   

    FC (Fiber Channel)- The FC connector was designed for use in high-vibration surroundings and thus has a “floating” ferrule design that keeps your connection tight even among high activity. This feature can save the day if needed, but it is important to remember to make your connections with caution as the same feature can cause an improperly angled connection to be just as secure. Although FC’s have been largely supplanted by SC and LC connectors, when you need one, there is nothing like an FC.

    MTRJ (Mechanical Transfer Registered Jack)- The MTRJ was developed to more efficiently use space in your interface- its small physical body makes it a popular connector for use with small form factor devices. The MTRJ is also able to run two fiber lines in its single clip/latch connection point.


Multifiber Connectors- MPO and MTP ® Technologies

    MPO (Multifiber Push-On) - also known as an array connector, the MPO is a high density connector able to terminate up to 72 fibers simultaneously. The connector body itself uses a simple push/pull method akin to the SC connector and features fiber lane assignment with numbered designations for each strand; MPO high density connectors are typically used in large scale systems.

    MTP ®  ( Multifiber Terminal Push-On) - The MTP ®  connector is US Conec’s trademarked high density connector- similar to the MPO in many ways but different in a few important ways too; the MTP ® , for example, allows for free ferrule movement for easier mating, features elliptical guide pins to decrease wear and tear, and has a removable housing for ferrule re-polishing and male/female pin swapping. These unique features make the MTP ®  an excellent high density connector.   Please note that MTP ®  connectors will work with MPO equipment, however MPO connectors are not compatible with MTP ®  equipment.  

 Remember, whatever connector you are using, if the connecter does not house the ferrule ALWAYS USE YOUR PROTECTIVE FERRULE CAPS WHEN NOT IN USE. Clean your ferrules every time you handles them! Damage to your ferrule represents critical damage to the functionality of your whole cable.


Color Code for Connectors

    The above list is comprised of7 of the most widely used and effective connector types; however there are to date upwards of 100 connector styles. In order to inject some rhyme and reason among all of  these connector types, the TIA (Telecommunications Industry Association) established color code TIA-568-C3 that is often but not always followed. The graph provided notes the color of the connector and/or adapter and its associated fiber type.

Cable Type

Connector/Adapter Type



Multimode 62.5 micron



Multimode 50 micron Standard



Multimode 50 micron Laser Optimized






Single-mode Angled (APC)





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At Cables For Less we offer a variety of high quality Fiber Optic solutions at great prices!

Visit our Fiber Optics section and shop from our ever-growing selection of patch cables such as 62.5/125 or 50/125 Multimode, Singlemode with any combination of LC, SC, ST, FC, MTP / MPO and MTRJ connectors. Of course we also carry a complete line of OM1, OM2 as well as 10GB OM3 and OM4 up to 100 Meters  Don’t see the fiber cable you need pre-made? Not a problem with our custom calculator, which allows you to build your fiber to exact specification! See our assortment of pre-made and customizable patch panels, collection of fiber couplers and termination boxes. Don’t forget our networking converters and MTP/MPO trunks, cassettes, and fan-out kits we even carry fiber optic cleaning supplies