What are the common fiber optic connector types?

[Fiber Optic Connector Types:](

FC round with threaded coupling, ST bayonet-style round, SC bayonet-style square, LC similar to SC but half the size, PC micro-spherical polished, APC angled at 8° with micro-spherical polishing, MRTJ square, one end with dual-fiber transceiver integrated (mostly used on 3com), fiber optic modules: generally support hot-swapping, GBIC mostly uses SC or ST fiber interfaces, SFP small form-factor GBIC, uses LC type fiber. Single-mode: L, wavelength 1310; single-mode long-haul LH, wavelength 1310, 1550; multimode: SM, wavelength 850; SX/LH indicates compatibility with both single-mode and multimode fiber.
Common fiber patch cord connector types are shown in the figures below:

The figure above shows LC to LC. LC is the connector commonly used with SFP and mini GBIC on routers.

The figure above shows FC to FC, which is also one of the commonly used fiber patch cords.

FC to SC. The FC end plugs into the fiber distribution frame, and the SC end connects to the GBIC port on a Catalyst or other device.

ST to FC. For 10Base-F connections, the connector is typically ST type, and the FC end connects to the fiber distribution frame.

SC to SC, both ends are GBIC.

SC to LC, one end GBIC, the other end MINI-GBIC.

FC round with threaded coupling (most commonly used on distribution frames)
ST bayonet-style round
SC bayonet-style square (most commonly used on routers and switches)
PC micro-spherical polished
APC angled at 8° with micro-spherical polishing
MT-RJ square, one end with dual-fiber transceiver integrated (used on Huawei 8850)
Fiber optic modules: generally support hot-swapping
GBIC Giga Bitrate Interface Converter, mostly uses SC or ST fiber interfaces
SFP small form-factor GBIC, uses LC type fiber
Fiber types used:
Single-mode: L, wavelength 1310; single-mode long-haul LH, wavelength 1310, 1550
Multimode: SM, wavelength 850
SX/LH indicates compatibility with single-mode or multimode fiber

In the labeling of pigtail connectors, we often see "FC/PC", "SC/PC", etc. The meanings are as follows:
The part before "/" indicates the connector type of the pigtail.
The "SC" connector is a standard square connector made of engineering plastic, featuring high temperature resistance and resistance to oxidation. The optical interface on the transmission equipment side generally uses SC connectors.
The "LC" connector is similar in shape to the SC connector but slightly smaller.
The "FC" connector is a metal connector, generally used on the ODF side. Metal connectors have a higher number of insertion/withdrawal cycles than plastic ones.

There are many connector varieties. In addition to the three types mentioned above, there are also MTRJ, ST, MU, etc.
The part after "/" indicates the polishing process of the fiber end face, i.e., the grinding method.
"PC" is the most widely used in telecom operator equipment, and its end face is flat.
"UPC" has lower attenuation than "PC" and is generally used in equipment with special requirements. Some foreign manufacturers use FC/UPC for internal patch cords in ODF frames, mainly to improve the specifications of the ODF equipment itself.