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Difference Between Four Fiber Optic Connectors ST, SC, FC, LC

Issuing time:2019-04-07 11:19Author:Cocoon Lee

Difference Between Four Fiber Optic Connectors ST, SC, FC, LC

ST, SC, FC fiber connector is the early industrial standard developed by different enterprises. The usage and effect of them are the same. each of them has its own advantages and disadvantages.

ST, SC connectors are commonly used in general networks. After the ST connector is inserted, it rotates for half a week and is fixed with a bayonet. SC connector can be directly plugged, it is easy to use, but it is easy to fall out; FC connector is generally used in telecommunication network, there is a nut screwed to the adapter, it is very strong and dustproof.

The MTRJ optic fiber patch cord consists of two high-precision plastic-formed connectors and cables. The external parts of the connector are precision plastic parts, including a push-pull type plug-in clamping structure. Suitable for indoor applications in telecommunication and data network systems.

fiber optic connectors

Types of optical fiber interface connectors

Fiber optic connectors, or fiber-optic connectors that connect to an optical module, also come in many varieties and are not interchangeable. People who are not regularly exposed to fiber optics may mistakenly assume that the fiber optic connectors for the GBIC and SFP modules are the same type, but they are not. The SFP module is connected to LC fiber optic connector, while the GBIC is connected to SC fiber optic connector. The following is a detailed description of several commonly used optical fiber connectors in network engineering:

(1) FC fiber optic connector: external strengthening is metal sleeve, fastening mode: screw. Generally used on the ODF side (the most used connector type);

(2) SC type fiber optic connector: used to connect the GBIC light module, its shell is rectangular, fastening mode is plug and pull pin latch, do not have to rotate (mostly used on router switch);

(3) ST type optical fiber connector: often used in optical fiber distribution frame, the shell is round, fastening mode: screw buckle. For a 10 Base-F connection, the connector is usually ST type (usually used on ODF);

(4) LC type optical fiber connector: connecting the SFP module, it is made of the convenient modular jack (RJ) latch mechanism (commonly used on routers);

(5)MT-RJ: square optical fiber connector with integrated transceiver, single end with dual fiber transceiver.

LC-LC fiber optic cable

SC-LC fiber optic cable

SC-SC fiber optic cable

ST-FC fiber optic cable

FC-SC fiber optic cable

Common types of fiber optic cables

Introduction to various types of fiber interface:

Optical fiber connectors

FC round with thread (the most commonly used on ODF)

ST snap type round

SC card type square (most used on router switch)

PC microsphere grinding and polishing

APC, 8 degree angle and microsphere grinding and polishing

MT-RJ square, single end dual fiber transceiver (used on Huawei 8850)

Optical fiber module: generally supports hot plugging,

GBIC Giga Bitrate Interface Converter, mostly SC or ST type

SFP small encapsulated GBIC, using optical fiber LC type

Fiber used:

Single mode: L, wavelength 1310;

Single mode long distance LH wavelength 1310, 1550

Multimode :SM, wavelength 850

SX/LH indicates that single-mode or multi-mode optical fibers can be used.

"FC/PC", "SC/PC", etc., are commonly seen in the labeling of tail fiber joints. Their meanings are as follows

The front part of "/" indicates the type of connector for the tailfin.

The "SC" connector is a standard square joint, which is made of engineering plastics and has the advantages of high temperature resistance and antioxidant. SC connector is generally used at the transmission equipment side.

The shape of "LC" joint is similar to that of SC joint, but smaller than that of SC joint.

"FC" joint is a metal joint, generally used on the ODF side, it can be plugged many more times than plastic material.

There are many kinds of signals for connectors. In addition to the three types introduced above, there are also MTRJ, ST, MU, etc. The specific appearance is shown in the figure below.

fiber optic connectors

The following part of "/" indicates the fiber joint cross-section process, or grinding mode.

"PC" is most widely used in telecom operators' equipment, the joint section is flat.

"UPC" has a smaller decay than "PC", generally used for equipment with special needs. Some manufacturers use FC/UPC for the internal patch cord of ODF frame, mainly to improve the index of ODF equipment itself.

In addition, the "APC" model is widely used in radio and television and early CATV. The tail fiber adopts the end face with inclination angle, which can improve TV signal quality. The main reason is that the TV signal is analog light modulation. Due to the uneven distribution of optical fiber refractive index, it will return to the coupling surface again. At this time, although the energy is very small, the analog signal cannot completely eliminate the noise, so it is equivalent to superimpose a weak signal with time delay on the original clear signal, which is shown in the picture as ghosting. The angle of the tail fiber strip can make the reflected light not return along the original path. General digital signal does not have this problem.

Fiber optic connector

Fiber optic connector is a removable connection part between optical fiber and optical fiber, it puts the two surface of fiber with precision docking, so that the output light energy of the transmitting fiber can be maximally transferred to the receiving fiber, and minimize the effects on the system due to its interference to the optical link--which is the basic requirement of optical fiber connector. To some extent, fiber optic connectors also affect the reliability and performance of optical transmission systems.

Fiber optic connectors can be divided into the common single-mode and multi-mode connectors of silicon-based fiber according to the different transmission media. And other fiber optic connectors such as those that use plastic as the medium of transmission. According to the connector structure can be divided into: FC, SC, ST, LC, D4, DIN, MU, MT and other forms. Among them, ST connector is usually used for wiring equipment terminal, such as optical fiber distribution frame, optical fiber module, etc.; SC and MT connectors are typically used on network devices. FC, PC (including SPC or UPC) and APC according to the shape of fiber end face; single core and multi-core (such as MT-RJ) according to the fiber core number. Fiber optic connectors are widely used and of various varieties. In the practical application, they are divided according to the different structure of optical fiber connector. Here are some common fiber optic connectors:

(1) FC fiber optic connector

Abbreviation of Ferrule Connector. The connector was first developed by Japan's NTT, which indicates that its external reinforcement is of the form of a metal sleeve with screw fastening mode. This kind of connector is simple in structure, easy to operate and easy to make. But the optical fiber end is sensitive to dust and easy to produce Fresnel reflection, so it is difficult to improve the performance of return loss. Later, this type of connector was improved by adopting a spherical pin (PC) on the butt surface, while the external structure was not changed, which greatly improved the performance of insertion loss and return loss.

(2) SC type fiber optic connector

This is a fiber optic connector developed by the Japanese company NTT. Its shell is rectangular, and the structure size of the plunger and coupling sleeve is exactly the same as FC type. PC or APC grinding mode is usually adopted for the end faces of the pins. Fastening method is plug and pull pin latch type, do not need to rotate. This kind of connector has the advantages of low price, convenient operation, small fluctuation of insertion loss, high compressive strength and high installation density.

ST and SC interfaces are two types of fiber optic connectors. For 10 Base-F connections, the connector is usually ST type, and for 100 Base-FX, the connector is mostly SC. The core of ST connector is exposed, and the core of SC connector is inside the connector.

(3) Biconic Connector

The most representative product of this type of fiber optic connector is developed by Alcatel-Lucent Bell Labs in the United States. It consists of two precision molded tapered cylindrical plugs with truncated ends and a coupling assembly with a plastic sleeve with a double cone inside.

(4) DIN47256 optical fiber connector

This is a connector developed in Germany. The structure size of the plunger and coupling sleeve adopted by this connector is the same as FC type. And the end face processing adopts PC grinding mode. Compared with FC connector, its structure is more complex. The internal metal structure has a pressure control spring, which can avoid the damage of the end face due to too much pressure plug. In addition, the mechanical precision of the connector is higher, so the insertion loss is small.

(5) MT-RJ connector

MT - RJ started in MT connectors developed by NTT. Wear the same latch mechanism of RJ-45 LAN electric connector. Alignment of the optical fiber with guide pins mounted on both sides of the small sleeve for easy connection to the optical transceiver. The connector end face fiber is designed as a dual-core (0.75mm interval) arrangement, mainly used for data transmission for the next generation of high density optical fiber connector.

(6) LC connector

LC connector is developed by the famous Alcatel-Lucent Bell Labs and is made by the convenient modular jack (RJ) latch mechanism. The size of the inserted needle and sleeve is one half of the size of ordinary SC, FC, etc., which is 1.25mm.This increases the density of fiber optic connectors in the fiber distribution frame. At present, in terms of single-mode SFF, LC type connectors have actually occupied a dominant position, and their applications in multi-mode are also growing rapidly.

(7) MU connector

MU(Miniature unit Coupling) connector is based on the SC connector that has been used the most, and has been developed by NTT as the world's smallest single-core fiber connector. The connector uses a 1.25mm diameter casing and self-retaining mechanism, which has the advantage of high density installation. Using MU's l.25mm diameter casing, NTT has developed a MU connector family. They have socket connectors (MU-A series) for optical cable connections; baseplate connectors with self-retaining mechanism (MU-B series) and simplified sockets for connecting LD/PD modules to plugs (MU-SR series) etc. With the rapid development of fiber network to larger bandwidth and larger capacity and the wide application of DWDM technology, the demand for MU connector will also grow rapidly.

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