Recognizing that there are quite a few connectors on market that are actively being used in fiber optic installations, there are  also some older types and discontinued connectors, not being used in the main stream of data and telco markets, but used in more specialized applications.

In addition to the mainstream connectors are variants on the end face geometry such as Angle and Radius end faces for specific applications.

The most common of currently used connectors are:

LC, SC, MT/MPO and FC, while the older types such as SMA, ST , D4, Escon , Biconic , VF45 and MTRJ are still being used in the specialty applications and older installed fiber bases of similar connector types.


  • LC

A high density connector for fiber optic applications used in both public and private networks. This high performance connector is available in both singlemode and multimode.

  • SC

Subscriber connector, a push/pull connector style that is recognized as the preferred optical fiber connector standard. It is available in simplex, duplex, hybrid, or hardened styles. The SC (Subscriber Carrier) fiber optic connector is one of three connectors (the other two are ST and SFF) approved by ANSI/TIA/EIA 568-B.3. The SC Connector’s main advantage is polarization since the connectors can be paired and keyed.

  • MT/MPO

Multi-channel (4 to 72) connector from USConec (MPO is generic version).

  • FC

A connector type used primarily for Singlemode fiberoptic cable. It offers precise alignment of the cable with respect to the transmitter and detector. Using a threaded receptacle and a locator notch, once installed the position is maintained with absolute accuracy.

  • SMA

(Subminiature A):  50 ohm - subminiature coaxial connector with screw type coupling mechanism. Frequency range DC-18 GHz.

  • ST

Type of connector used on fiber optic cable utilizing a spring loaded twist and lock coupling similar to the BNC connectors used with coaxial cabling.

  • D4

D4 connectors are made from a 2.5mm diameter ceramic (zirconia) ferrule for durability and one of the older generation connectors which is keyed, and spring loaded and has a 2mm diameter ferrule.


ESCON (Enterprise Systems Connection) is a data connection created by IBM, and is commonly used to connect their mainframe computers to peripheral devices such as disk storage and tape drives. ESCON is an optical fiber, half-duplex, serial interface. … ESCON was introduced by IBM in the early 1990s.

  • Biconic

A phenolic-bodied, threaded, spring-loaded, non-keyed connector with a cone-shaped alignment area.

  • VF45

Duplex fiber connectors primarily used in fiber-to-the-desk LAN applications.

  • MTRJ

MT-RJ connector. MT-RJ connector. A fiber-optic cable connector that is very popular for small form factor devices due to its small size. Housing two fibers and mating together with locating pins on the plug, the MT-RJ comes from the MT connector, which can contain up to 12 fibers.

European and Japanese Connectors

European and Japanese Connectors are more widely used in specific parts of the world beside Europe and Japan. These are the DIN, E2000 and MU connectors.

  • DIN

DIN connector is an electrical connector that was originally standardized in the early 1970s by the Deutsches Institut für Normung (DIN), the German national standards organization. … Some DIN connector standards are: DIN 41524, for circular connectors often used for audio signals.

  • E2000

E2000 connector looks like a miniature SC connector. The connector is easy to install, with a push-pull latching mechanism which clicks when fully inserted. It features a spring-loaded shutter which fully protects the ferrule from dust and scratches.

  • MU

MU Connector is a small form factor SC that looks like a miniature SC with a 1.25 mm ferrule. It is a popular connector type in Japan.

Fiber Optic Contacts

Fiber optic contacts, similar to the installation/processing of standard connectors, are widely used in “multi contact Hybrid circular connectors” that contain from 2- 12 Fiber Optic contacts alongside electrical contacts. Examples are the Luxcis 801, Mil 29504, and others under various names and applications such as:

  • Broadcast Industry
  • Oil and Gas
  • Defense/Military
  • Commercial and Mil Aviation
  • Medical
  • Industrial

FOC Glossary includes Glossary Definitions, Acronyms, and Military Specifications for Connectors


EDITOR’S NOTE: This is the third article in an ongoing series, “Introduction to Fiber Optic Cable Assembly Manufacturing.”:


This article includes

  • Key components of Fiber Optic Connectors and Key Specifications of Connectors
  • Key components of fiber optic connectors
  • Key specifications of connectors
    • Connector housing
    • Ferrule
    • Flange
    • Crimp sleeve
    • Strain relief boot
    • Spring
    • Backshell
  • Key specifications of connectors
    • Ferrule hole diameter
    • Ferrule hole
    • Ferrule hole to outside diameter (OD)


FOC Technical Paper for Download:

The “Ideal” Fiber Height for a Fiber Optic Connector – and How to Achieve It


From the FOC Library of Blog Articles on Connectors: 


Additional resources to continue your education:


Follow Mario Goduco @PolishExprtFOC

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