For jumpers with the same type of connector, whether the suffix is UPC or APC, the prices and uses are different. The difference is all in the geometry of the end face grinding and the resulting difference in return loss. The wrong choice will affect the entire link.
End face geometry determines reflection
PC is spherically polished, allowing the end faces of the two optical fibers to be in slight contact; UPC makes the end face flatter on this basis to reduce end face reflection; APC grinds the end face into an 8° bevel angle to allow the reflected light to deviate from the fiber core, so the return loss is significantly higher and is more friendly to reflection-sensitive systems.
Common ranges for return loss
Return loss is a measure of how weak the light is reflected back to the source, with the higher the number, the better. Common requirements ranges in engineering are as follows.
- UPC single-mode return loss generally requires more than 50dB.
- The APC can usually reach over 60dB, and the bevel angle makes the back reflection weaker.
- CATV and single-fiber bidirectional wavelength division links mostly use APC to avoid reflections that affect signal quality.
High reflection will degrade analog video and long-distance links, EB-LINKSC-SC single mode single core jumperThe models are divided into UPC and APC supplies, and you can place an order according to the scenario.
What will mixed penetration bring?
APC and UPC should not be forcibly inserted into each other: 8° contact between the end face and the flat surface will cause excessive local pressure, scratch the ferrule and even the ceramic hole of the adapter, and the more they are inserted, the worse it will be. The interface color is usually green for APC and blue for UPC. Color matching during construction can reduce mis-insertion.
Choose grinding based on the return loss requirements. Don't just swap the joints if they have the same appearance. The cost of rework is much higher than choosing the right one.