# Optical fiber connector

An optical fiber connector is a device used to link optical fibers, facilitating the efficient transmission of light signals. An optical fiber connector enables quicker connection and disconnection than splicing.
They come in various types like SC, LC, ST, and MTP, each designed for specific applications. In all, about 100 different types of fiber optic connectors have been introduced to the market.
These connectors include components such as ferrules and alignment sleeves for precise fiber alignment. Quality connectors lose very little light due to reflection or misalignment of the fibers.
Optical fiber connectors are categorized into single-mode and multimode types based on their distinct characteristics. Industry standards ensure compatibility among different connector types and manufacturers. These connectors find applications in telecommunications, data centers, and industrial settings.

## Application

Optical fiber connectors are used to join optical fibers where a connect/disconnect capability is required. Due to the polishing and tuning procedures that may be incorporated into optical connector manufacturing, connectors are often assembled onto optical fiber in a supplier's manufacturing facility. However, the assembly and polishing operations involved can be performed in the field, for example, to terminate long runs at a patch panel.
Optical fiber connectors are used in telephone exchanges, for customer premises wiring, and in outside plant applications to connect equipment and fiber-optic cables, or to cross-connect cables.
Most optical fiber connectors are spring-loaded, so the fiber faces are pressed together when the connectors are mated. The resulting glass-to-glass or plastic-to-plastic contact eliminates signal losses that would be caused by an air gap between the joined fibers.
Performance of optical fiber connectors can be quantified by insertion loss and return loss. Measurements of these parameters are now defined in IEC standard 61753-1. The standard gives five grades for insertion loss from A (best) to D (worst), and M for multimode. The other parameter is return loss, with grades from 1 (best) to 5 (worst).
A variety of optical fiber connectors are available, but SC and LC connectors are the most common types of connectors on the market. Typical connectors are rated for 500–1,000 mating cycles. 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.
In many data center applications, small (e.g., LC) and multi-fiber (e.g., MTP/MPO) connectors have replaced larger, older styles (e.g., SC), allowing more fiber ports per unit of rack space.
Outside plant applications may require connectors be located underground, or on outdoor walls or utility poles. In such settings, protective enclosures are often used, and fall into two broad categories: hermetic (sealed) and free-breathing. Hermetic cases prevent entry of moisture and air but, lacking ventilation, can become hot if exposed to sunlight or other sources of heat. Free-breathing enclosures, on the other hand, allow ventilation, but can also admit moisture, insects and airborne contaminants. Selection of the correct housing depends on the cable and connector type, the location, and environmental factors.

## Types

Many types of optical connector have been developed at different times, and for different purposes. Many of them are summarized in the tables below.
Fiber connector types :
| Short name | Full name | Coupling type | Screw thread | Ferrule diameter | Standard | Applications and notes |
| Avio (Avim) | Aviation Intermediate Maintenance | Screw | | | | Aerospace and avionics |
| ADT-UNI | | Screw | | 2.5 mm | | Measurement equipment |
| CS | Corning/Senko | Latch, push-pull | — | 1.25 mm | | Listed in SFF-8024 |
| DMI | Diamond Micro Interface | Latch, separate | — | 2.5 mm | | Printed circuit boards |
| LSH or E-2000 | | Latch, push-pull, integral dust cap | — | 2.5 mm | IEC 61754-15 | Telecom, DWDM systems |
| ECCF08 | | Latch, push-pull | — | | IEC 1754-8 | Telecom and CATV networks |
| ELIO | | Bayonet | — | 2.5 mm | ABS1379 | PC or UPC |
| ESCON | Enterprise Systems Connection | Latch, integral shroud | — | 2.5 mm | | IBM mainframe computers and peripherals |
| F07 | | | | 2.5 mm | Japanese Industrial Standard (JIS) | LAN, audio systems; for 200 μm fibers, simple field termination possible, mates with ST connectors |
| F-3000 | | Latch, integral light- and dust-cap | — | 1.25 mm | IEC 61754-20 | Fiber To The Home (LC compatible) |
| FC | Ferrule Connector or Fiber Channel | Screw | M8×0.75 | 2.5 mm | IEC 61754-13 | Datacom, telecom, measurement equipment, single-mode lasers |
| Fibergate | | Latch, integral dust-cap | — | 1.25 mm | | Backplane connector |
| FJ | Fiber-Jack or Opti-Jack | Latch | — | 2.5 mm | | Building wiring, wall outlets |
| LC | Lucent Connector, Little Connector, or Local Connector | Latch | — | 1.25 mm | IEC 61754-20 | High-density connections, SFP and SFP+ transceivers, XFP transceivers. Duplex LC is comparable in size to RJ-45. |
| Luxcis | | | | 1.25 mm | ARINC 801 | PC (straight physical contact) or APC (angled physical contact) configurations |
| LX-5 | | Latch, integral light- and dust-cap | — | | IEC 61754-23 | High-density connections; rarely used |
| M12-FO | | Screw | M16 | 2.5 mm | EN 61754-27, ISO/IEC 61754-27 | Machine, process and plant engineering. IP-67 dust and water resistant |
| MICFDDI | Media Interface ConnectorFiber distributed data interface | Snap | — | 2.5 mm | | |
| MPO orMTP | Multiple-fiber Push-On/Pull-off | Snap, push-pull, gendered | — | 2.5×6.4 mm | IEC-61754-7; EIA/TIA-604-5 (FOCIS 5) | SM or MM multi-fiber ribbon. Same ferrule as MT, but more easily reconnectable. Used for indoor cabling and device interconnections. MTP is a brand name for an improved connector, which intermates with MPO. |
| MT | Mechanical Transfer | Latch, gendered | — | 2.5×6.4 mm | | Pre-terminated cable assemblies; outdoor applications |
| MT-RJ | Mechanical Transfer Registered Jack or Media Termination - recommended jack | Latch, gendered | — | 2.45×4.4 mm | IEC 61754-18 | Duplex multimode connections |
| MU | Miniature unit | Latch, push-pull | — | 1.25 mm | IEC 61754-6 | Common in Japan |
| SC | Subscriber connector, square connector or standard connector | Latch, push-pull | — | 2.5 mm | IEC 61754-4 | Datacom and telecom (most widely deployed); GPON; EPON; GBIC; MADI |
| SC-DCSC-QC | SC-Dual ContactSC-Quattro Contact | Latch, push-pull | — | 2.5 mm | IEC 61754-4 | Datacom and telecom; GPON; EPON; GBIC |
| SMA 905F-SMA I | Sub Miniature A | Screw, optionally keyed | ⁠1/4⁠″-36 UNS 2B | 3.17 mm | IEC 60874-2 | Industrial lasers, optical spectrometers, military; telecom multimode |
| SMA 906F-SMA II | Sub Miniature A | Screw | ⁠1/4⁠″-36 UNS 2B | Stepped; 0.118 to 0.089 in 3.0 to 2.3 mm, typ. | IEC 60874-2 | Industrial lasers, military; telecom multimode |
| SMC | Sub Miniature C | Snap | — | 2.5 mm | | |
| ST orBFOC | Straight Tip or Bayonet Fiber Optic Connector | Bayonet | — | 2.5 mm | IEC 61754-2 | Datacom |
| F05 | | Snap-in, clip | — | | JIS C 5974 | Digital audio, used in select TOSLINK devices |
| VF-45SG | Volition Fiber | Latch | — | None, V-grooves as guidance | | Datacom |
| 1053 HDTV | Broadcast connector interface | Push-pull coupling | — | 1.25 mm ceramic | | Audio & data (broadcasting) |
| V-PIN | V-System | Snap-fit, push-pull | — | | | Industrial and electric utility networking; multimode 200 μm, 400 μm, 1 mm, 2.2 mm fibers |