Several optical fiber connectors (ST, SC, LC, FC) and the difference between PC, APC and UPC

Introduction of several types of optical fiber interfaces

Fiber optic connector (also known as fiber jumper) means that both ends of the optical fiber are equipped with connector plugs to realize the active connection of the optical path; the transceiver wavelengths of the optical modules at both ends of the optical fiber jumper must be the same, that is to say The simple way to distinguish optical modules of the same wavelength is to have the same color. Generally, short-wave optical modules use multi-mode fibers (orange fibers), and long-wave optical modules use single-mode fibers (yellow fibers) to ensure the accuracy of data transmission.
One end with a plug is called a pigtail. The function of the pigtail is mainly to connect the connectors at both ends of the optical fiber. One end of the pigtail is fusion spliced with the optical fiber connector, and the other end is connected to the optical fiber transceiver or the optical fiber module through a special connector (FC, ST, SC, LC, MTRJ). Data transmission path.

Optical fiber connector (FC/APC, FC/UPC, SC/UPC, etc.)the back part of “/” indicates the cross-section process of the fiber connector, that is, the grinding method. The front part of “/” indicates the connector model of the pigtail
FC round with thread (most used on patch panels)
ST snap-on round
SC card-connected square type (most used on router switches)
PC microsphere grinding and polishing
APC is at an angle of 8 degrees and is microspherically polished
MT-RJ square type, one dual fiber transceiver integrated

Fiber optic connectors can be divided into: FC, SC, ST, LC, D4, DIN, MU, MT-RJ and other types according to the structure of the connector. Among the eight types of connectors, we are most commonly used in the usual LAN engineering and the industry. The most popular ones are FC, SC, ST, LC, MT-RJ. Only when we know these interfaces, can we correctly purchase fiber optic jumpers, pigtails, GBIC fiber modules, SFP (mini GBIC) fiber modules, and fiber optic cables in the project. Interface switches, fiber optic transceivers, couplers (or adapters). The pin grinding

FC round with thread (most used on patch panels)
ST snap-on round
SC card-connected square type (most used on router switches)
PC microsphere grinding and polishing
APC is at an angle of 8 degrees and is microspherically polished
MT-RJ square type, a dual-fiber transceiver integrated (useful on Huawei 8850)

Optical fiber module: generally supports hot swap,
GBIC Giga Bitrate Interface Converter, the optical fiber interface used is mostly SC or ST type
SFP small package GBIC, the optical fiber used is LC type
Fiber used:
Single mode: L, wavelength 1310 Single mode long distance LH wavelength 1310, 1550
Multimode: SM wavelength 850
SX/LH means single-mode or multi-mode fiber can be used
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In the label indicating the pigtail connector, we can often see “FC/PC”, “SC/PC”, etc. The meanings are as follows
The front part of “/” indicates the connector model of the pigtail
The “SC” connector is a standard square connector, using engineering plastics, which has the advantages of high temperature resistance and not easy to oxidize. The optical interface of the transmission equipment side generally uses the SC connector
The “LC” connector is similar in shape to the SC connector, but smaller than the SC connector.
The “FC” connector is a metal connector, which is generally used on the ODF side. The metal connector can be plugged in more times than plastic.

In the label indicating the pigtail connector, we can often see “FC/PC”, “SC/PC”, etc. The meanings are as follows
The front part of “/” indicates the connector model of the pigtail
The “SC” connector is a standard square connector, using engineering plastics, which has the advantages of high temperature resistance and not easy to oxidize. The optical interface on the transmission equipment side generally uses an SC connector. The “LC” connector is similar in shape to the SC connector, but smaller than the SC connector.
The “FC” connector is a metal connector, which is generally used on the ODF side. The number of plug-in times of the metal connector is longer than that of plastic
There are many types of connector signals, in addition to the three introduced above, there are MTRJ, ST, MU, etc.
“/” indicates the cross-section process of the fiber connector, that is, the grinding method.
“PC” is the most widely used in telecom operators’ equipment, and its joint section is flat.

“SC” means that the pigtail connector is SC connector. The optical interface on the transmission equipment side in the industry generally uses SC connector. The SC connector is engineering plastic, which has the advantages of high temperature resistance and not easy to oxidize; ODF side optical interface generally uses FC connector, FC It is a metal connector, but the ODF will not have high temperature problems. At the same time, the number of plug-in times of the metal connector is more than that of plastic. The maintenance of the ODF pigtail is more than that of the optical fiber pigtail. Other common connector models are: ST, DIN, FDDI.
“PC” stands for the cross-section process of optical fiber connector, and PC is the most common. The APC model is widely used in radio and television and early CATV. The pigtail head uses an end face with an inclination angle. The slope is generally invisible, which can improve the quality of the TV signal. The main reason is that the TV signal is analog light modulation. When the coupling surface of the connector is vertical, the reflected light returns along the original path. Because the non-uniformity of the fiber refractive index distribution will return to the coupling surface again, at this time, although the energy is small, the analog signal cannot completely eliminate noise, so it is equivalent to superimposing a weak signal with time delay on the original clear signal. It is ghosting on the screen. The inclination of the pigtail headband prevents the reflected light from returning along the original path. Generally, digital signals generally do not have this problem.
There is also a “UPC” process. Its attenuation is lower than that of PC. Generally, the enamel plate of equipment with special needs is generally FC/UPC. Foreign manufacturers use FC/UPC for fiber jumpers inside ODF racks to improve the ODF equipment’s own indicators.

Optical fiber interface
Optical fiber interface is a physical interface used to connect optical fiber cables. Usually there are SC, ST, FC and other types, they are developed by Japan NTT company. FC is the abbreviation of Ferrule Connector. The external reinforcement method is a metal sleeve and the fastening method is a turnbuckle. The ST interface is usually used for 10Base-F, and the SC interface is usually used for 100Base-FX.