Fiber Optic Connectors
Fiber optic connectors terminate both ends of an optical fiber. A variety of fiber optic connectors are available. The differences between the types of connectors are the size as well as the methods of coupling. There are four types of fiber optic connector in use. The list of all types of fiber optic connectors is following. We should discuss the first four fiber optic connectors in detail.
- ST Connector (ST)
- Standard Connector (SC)
- Lucent Connector (LC)
- Ferrule Core Connector (FC)
- Bionic Connector
- SMA Connector
- E2000 Connector
- Enterprise Systems Connection Connector (ESCON)
- Plastic Fiber Optic Cable Connectors
- MT Connector
- Opti-Jack Connector
- Fiber Distributed Data Interface Connector (FDDI)
- LX-5 Connector
- Volition Connector
- MU Connector
- MT-RJ Connector
ST Connectors
The ST connector was one of the first connector types broadly implement in fiber optic networking applications. It 
was the most popular connector for the multimode network. It was originally developed by AT&T, it stands for Straight Tip connector. ST connectors use a 2.5mm ferrule with round plastic or metal body. The connector stays in place with a “twist-on/twist-off” bayonet-style mechanism.
Although extremely popular for many years, the ST connector slowly replaced with smaller, denser connectors in many installations. The SC/FC/FDDI/ ESCON connectors have the same ferrule size – 2.5 mm or about 0.1 inch – so they can be mixed and matched to each other using hybrid mating adapters. STs Connectors are spring-loaded, So it is necessary to make sure they are seated properly. If you have high loss, open the connector and reconnect it to see if it makes a difference.
SC Connector
Simple, rugged and low cost, SC connectors use a ceramic 2.5 mm ferrule to deliver accurate alignment of the SMF.
They use a push-on/pull-off mating mechanism which is usually easy to use than the twist-style ST connector when in tight spaces. The connector body of an SC connector is square-shaped.
Two SC connectors usually held together with a plastic clip (referred to as a duplex connection). Japanese telecommunications company NTT originally developed SC and believed to be an abbreviation for Subscriber Connector or possibly Standard Connector.
LC connector
The Lucent Connector sometimes called the Little Connector, the popular Small Form Factor (SFF) connector. This 
interface was developed by Lucent Technologies. It uses a retaining tab mechanism; similar to a phone or RJ-45 connector, and the connector body resembles the square type shape of SC connector.
LC connectors normally held together in a duplex configuration with a plastic clip. The ferrule of an LC connector is 1.25mm. There are 3 different types of LC connectors:
- Single Mode LC APC
- Single Mode LC UPC
- Multi-Mode LC UPC
Ferrule Core Connector (FC)
Ferrule Core Connector (FC) was the most popular single-mode connectors for several years. It uses a 2.5 mm ferrule 
core, but some of the early connectors use ceramic inside stainless steel ferrules.
It screws on firmly, but you must make sure you have the key aligned; in the slot properly before tightening FC connector is a pretty common choice for example in Video over Fiber Transmission Equipment.
