Optical fiber connector

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Duplex LC connector

Duplex MT-RJ connector

SC connectors

ST connector

TOSLINK connector

An optical fiber connector terminates the end of an optical fiber, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so that light can pass. A variety of optical fiber connectors are available. The main differences among types of connectors are dimensions and methods of mechanical coupling. Generally, organizations will standardize on one kind of connector, depending on what equipment they commonly use, or per type of fiber (one for multimode, one for singlemode).

1 Types
- 1.1 Notes
- 1.2 Mnemonics
2 Analysis
3 References
4 External links

Types

Fiber connector types
Short name	Long form	Coupling type	Ferrule diamaeter	Typical applications
Avio (Avim)		Screw		Aerospace and avionics
ADT-UNI		Screw	2.5 mm	Measurement equipment
Biconic		Screw	2.5 mm	Obsolete
D4		Screw		Telecom in the 1970s and 1980s, obsolete
Deutsch 1000		Screw		Telecom, obsolete
DIN (LSA)		Screw		Telecom in Germany in 1990s; measurement equipment; obsolete
DMI		Screw	2.5 mm	Printed circuit boards
E-2000		Snap, with light and dust-cap	2.5 mm	Telecom, DWDM systems; becoming less common
ESCON	Enterprise Systems Connection	Snap (duplex)	2.5 mm	IBM mainframe computers and peripherals
F-3000		Snap, with light and dust-cap		Not as popular as LC
FC	Ferrule Connector	Screw	2.5 mm	Datacom, telecom, measurement equipment, single mode lasers (becoming less common)
LC	Lucent Connector or Local Connector	Snap	1.25 mm	High-density connections, SFP transceivers
LX-5		Snap, with light- and dust-cap		High-density connections, rarely used
MIC	Media Interface Connector	Snap	2.5 mm	Fiber distributed data interface (FDDI)
MPO	Multi-Fibre Push On	Snap
MT	Mechanical Transfer	Snap (12-plex)		Pre-terminated cable assemblies
MTP/MPO		Snap		multi fiber
MT-RJ	Mechanical Transfer Registered Jack	Snap (duplex)		Duplex multimode connections
MU		Snap	1.25 mm	Common in Japan
NEC D4		Screw		Common in Japan telecom in 1980s
Opti-Jack		Snap (duplex)
OPTIMATE		Screw		Platic fiber, obsolete
SC	Subscriber Connector or Standard Connector or Siemon Connector	Snap	2.5 mm	Datacom, telecom, becoming less common
SMA	Sub Miniature A	Screw	3.14 mm	Industrial lasers, military applications
SMC	Sub Miniature C	Snap	2.5 mm
ST / BFOC	Straight Tip / Bayonet Fiber Optic Connector	Bayonet	2.5 mm	Multimode networks
TOSLINK	Toshiba Link	Snap		Digital audio
VF-45		Snap		Datacom

Notes

If the fiber-end is angled to reduce back reflections this is usually described by adding "APC" (Angled Physical Contact) to the name.
SMA 905 features a "step" in the ferrule, while SMA 906 uses a straight ferrule

Mnemonics

LC connectors are sometimes called "Little Connectors".
MT-RJ connectors look like a miniature 8P8C connector — commonly (but erroneously) referred to as RJ-45.
ST connectors have a mnemonic of "Stab and Twist", referring to how it is inserted (the cable is pushed into the receiver, and the outer barrel is twisted to lock it into place). Also they are known as "Square Top" due to the flat end face.
SC connectors have a mnemonic of "Square Connector", and some people believe that to be the correct name. This refers to the fact the connectors themselves are square. Another term often used for SC connectors is "Stick and Click".
FCA are referred to as "Fiber Connector Angled".

Analysis

FC connectors' floating ferrule provides good mechanical isolation. FC connectors need to be mated more carefully than the push-pull types due to the need to align the key, and due to the risk of scratching the fiber endface while inserting the ferrule into the jack. FC connectors have been replaced in many applications by SC and LC connectors.^[1]
There are two common types of FC connectors, FCA and FCU. FCAs, unlike their FCU counterparts, have an angled end face which reduces the amount of light reflected back to the transmitter by bending the wave at the connectors. Similar to shining a flashlight directly at a mirror as opposed to angling it down. FCAs are distinguished with a green boot for strain relief. FCUs look identical but have a flat top.
FC connectors come with two different key diameters: 2 mm and 2.14 mm
SC connectors offer excellent packing density, and their push-pull design reduces the chance of fiber endface contact damage during connection.
LC connectors are replacing SC connectors in corporate networking environments due to their smaller size; they are often found on small form-factor pluggable transceivers.
ST connectors have a key which prevents rotation of the ceramic ferrule, and a bayonet lock similar to a BNC shell.
In general the insertion loss should not exceed 0.75 dB and the return loss should be higher than 20 dB. Typical insertion repeatability, the difference in insertion loss between one plugging and another, is 0.2 dB.
On all connectors, cleaning the ceramic ferrule before each connection helps prevent scratches and extends the connector life substantially.
Only connector with the same ferrule diameter can be mated with special adapters. E.g. a 1.25 mm ferrule diameter LC connector can not be connected to a 2.5 mm ferrule diameter SC connector.