Ultra Physical Contact, a polish in which the ferrule end face is domed and finished very smoothly so the two fiber cores touch with no air gap. Reflectance is typically around minus 50 to minus 55 dB, good enough for most Ethernet and SONET singlemode links. Singlemode UPC connectors are blue; the plain PC grade has reflectance of only about minus 40 dB.
Switch optics are LC/UPC, so the data center side stays blue and only the PON plant goes green.
Also heard as
- ultra polish
- blue connector
Do not mix it up with
- APC: APC adds an 8 degree angle for much lower reflectance, and the two styles must never be mated together.
Related terms
APC
Angled Physical Contact: a singlemode connector polish with an 8 degree angle that sends reflections into the cladding.
Reflectance
The fraction of light reflected by a single event such as a connector, in dB, where more negative is better.
End face
The polished tip of a connector ferrule and fiber, where light leaves one fiber and enters the next.
Connector
A removable termination that aligns the end of one fiber with another so light passes between them.