How to Choose the Proper Fiber Optic Connector for Your FTTH (Fiber To The Home) Installation
Fiber optic connectors can be divided into three groups: simplex, duplex and multiple fiber connectors.
Simplex connector means only one fiber is terminated in the connector. Simplex
connectors include FC, ST, SC, LC, MU and SMA.
Duplex connector means two fibers are terminated in the connector. Duplex connectors
include SC, LC, MU and MT-RJ. (Note: SC, LC and MU connectors have both simplex and duplex version)
Multiple fiber connector means more than two fibers (for up to 24 fiber) are terminated
in the connector. These are usually ribbon fibers with fiber count of 4, 6, 8, 12 and 24.
The most popular ribbon fiber connector is MT connector.
Now let's examine each type of connector closely.
FC stands for Fixed Connection and it was developed by Japanese company NEC (Nippon
Electric Co.). It has a screw on locking mechanism and is more popular in single mode
applications than in multimode applications. FC connectors are popular in test environments
and long haul applications. FC was once the most popular connector but now is being replaced
by SC and LC connectors. FC connector is available only in simplex version.
Advantages: lowest insertion loss, excellent repeatability
Disadvantage: Bulky, simplex version only, screw-on mechanism is hard to operate in a
busy telecom closet.
ST stands for Straight Tip. ST connector has a bayonet twist locking mechanism and was
developed by AT&T in the 1980s. ST connectors were predominant in the early 1990s but now
they are being replaced by SC and LC connectors. ST connectors are most common for
multimode applications. ST connectors are available in simplex version only.
Advantages: ST connector can be easily inserted and removed thanks to its spring-loaded
bayonet locking mechanism.
Disadvantages: Its locking mechanism design are both a bless and a curse. You have to
make sure the connector is seated in its socket securely and properly. It may be necessary
to remove and reconnect your ST connector if you experience high insertion loss. But if
you did it correctly, less than 0.3dB connection loss could be easily achieved.
SC stands for Subscriber Connector and was developed by Japanese company NTT. It is a
square shaped push/pull type connector with a snap-in locking mechanism. Because of its
easy locking mechanism and excellent repeatability, SC connector has become the dominant
connector since late 1990s, especially in multimode applications. SC connectors are
available in both simplex and duplex version.
Advantages: Easy push/pull snap-in locking mechanism, low cost, excellent
repeatability, low insertion loss
Disadvantages: Bulky footprint. Modern high speed fiber optic networks need more
compact connectors. LC connector is almost half the size of a SC connector and is becoming
more popular, especially in single mode applications.