Optical fiber ferrule polishing: PC, UPC and APC
* PC: Physical Contact. The ferrule is beveled and finished in a plain surface. This avoids empty spaces between the ferrules of the connectors being coupled, and achieves insertion losses among -30 dB and -40 dB. Its use is increasingly falling out.
* UPC: Ultra Physical contact. They are similar to the PC connectors, allowing decreasing return losses to a margin between -40 and -55 dB thanks to the sharper curve of the bevel. The current trend is using it in dead lines to allow operators to perform networks tests for example by using an OTDR.
* APC: Angled Physical Contact. The ferrule ends in a plain, 8 degree angled surface making it the connector that achieves a best optical link because it cuts down the return losses up the -60 dB thus allowing increasing the number of users in single mode fibers. For this reason, combined to its constantly decreasing manufacturing costs, APC has become the most used polishing type.