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Fiber Optic Connector Applications

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:: What is the difference between UPC and APC fiber optic connectors ?

By definition, the above are acronyms for the following:

UPC: Ultra Physical Contact

APC: Angled Physical Contact

The typical reason for the APC connector is a lower light reflectance. Nominal specification are as follows:

-55 dB for UPC connectors


-65 dB for APC connectors

This makes APC cables ideal for system components that are light-sensitive. The design of an APC connector results in less insertion loss (0.2 dB) at the interface.

:: PC, UPC and APC fiber optic patch cable assemblies

Usually we hear about descriptions like "LC/UPC single mode duplex fiber optic patch cord 3 meters", or "FC/APC single mode fiber optic pigtails", "ST/PC multi mode duplex fiber optic jumper". What do these words PC, UPC, APC mean?

As we know, fiber optic cable assemblies are mainly with connectors and cables, so the fiber cable assembly names is related to the connector names, we call it LC fiber patch cord, because it is with LC fiber connector, here the words PC, UPC, APC also are related only to the fiber optic connectors and has nothing to do with fiber optic cables.

We have known that PC, UPC, APC is standard of the fiber optic connectors, PC, UPC, APC are short for:

Physical Contact (PC)


Ultra Physical Contact (UPC)


Angled Physical Contact (APC)


These are actually the polish style of fiber optic ferrules. Unlike copper cables with copper thread in the connectors as connection media, fiber optic connectors are with these ceramic ferrules for connection, and different fiber optic connectors the ferrule size and length and polish styles are different. Such ferrules are inside the fiber optic connectors.

The different polish of the fiber optic connector ferrules result in different performance, mainly on the back reflection (return loss). Generally, PC type is required to have -40dB return loss or lower, UPC is -50dB or lower, APC is -60dB or lower.

Insertion loss of them all should be less than 0.3dB, with the lower the insertion loss being the better the performance.

Single mode fiber optic cables can be with PC, UPC or APC polished connectors, while multimode fibers only made with PC connectors.

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