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Cablek industries Services News Technical reference
Fiber Optic PC, UPC, and APC Connector Polishes
In general Cablek ships multimode cables with PC connectors and singlemode cables with UPC connectors or APC when specified, click here for all our fiber optics products
By definition, the above are acronyms for the following:
PC       Physical Contact
UPC    Ultra Physical Contact
APC    Angled Physical Contact
The typical reason for the APC connector is a lower lightwave reflectance.
Nominal specifications are as follows:
-40 dB for PC connectors  vs  -50 dB for UPC connectors  vs  -60 dB for APC connectors
What is the difference between PC, UPC and APC fiber optic patch cable assemblies?
The different polishes of the fiber optic connector ferrules result in different performances of the cables, mainly on the back reflection (return loss).   Various polish profiles are used, depending on the type of fiber and the application.
RETURN LOSS:  Whenever a connector is installed on the end of fiber, loss is incurred. Some of this light loss is reflected directly back down the fiber towards the light source that generated it. These back reflections, or Optical Return Loss (ORL), will damage the Laser Light Sources and also disrupt the transmitted signal.

PC polish,  the fiber ends are typically polished with a slight curvature, such that when the connectors are mated the fibers touch only at their cores. This is known as a "physical contact" (PC) polish. A typical hand polished connector will measure at –30dB.

UPC polish, to reduce the back reflection of a connector, it can be polished to UPC (Ultra Physical Contact) polish  SPC or (Super Physical Contact) polish. Industry standard is a minimum of –40dB for SPC back reflection measurement and –50dB for UPC back reflection measurement.

APC polish, If even less back reflection is required, an APC, or Angled Physical Contact polish, might be necessary. An APC connector has an 8º angle cut into the ferrule. These connectors are identifiable by their green color. APC-FIBER-GREEN-CONNECTOR.jpgAn APC polished connector has an Industry Standard Minimum of –60dB ORL measurement. APC fiber ends have low back reflection even when disconnected.


APC (Green) VS UPC (Blue)
Generally, PC type is required to have at least a 40dB return loss or higher, UPC is 50dB or higher, APC is 60dB or higher. (The higher the return loss the better the performance).
Insertion loss:  should be less than  0.3dB, the lower the insertion loss the better the performance.
Single mode fiber optic cables can be with PC, UPC or APC polished connectors, while multimode there is no APC ones.

PC, UPC, APC are short for:
Physical Contact (PC)
Ultra Physical Contact (UPC)
Angled Physical Contact (APC)

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