What is the difference between SC/APC and SC/UPC?

20/02/2023 Langzhi


1、 The treatment of plug end face is different

The end face of UPC is a plane with a certain radian, while the end face of APC is an inclined plane with an angle of 8 degrees.

The end face of APC (Angled Pressed Connector) is ground to an angle of 8 degrees, which is inclined to reduce reflection. Its industrial standard return loss is - 60dB, and APC can only be connected with APC.

2、 Different structure

The structure of APC is completely different from that of UPC. If the two connectors are connected with flanges, the fiber end face of the connector will be damaged. The way to connect APC to PC: through the optical fiber jumper of PC to APC conversion. In addition, it should be noted that the APC connector is usually green (while the yellow optical fiber is only single-mode optical fiber), and the tilt of the end face of the optical fiber can be seen by the human eye. The PC connector is usually blue.

3、 Connector color is different

Optical fiber jumpers have SC  FC  LC  ST interfaces, which are generally indicated in blue or black, and their interfaces are flat. UPC is a step plane developed based on PC structure. At present, the connectors of the optical fiber patch cord plane interface are UPC.

Extended data:

The return loss specified in PC, SPC and UPC industrial standards is - 35dB, - 40dB and - 50dB respectively (return loss refers to the proportion of light reflected by the end face of the connector. The smaller the return loss is, the better. Of course, you can also say that the larger the return loss is, the better, regardless of the previous negative sign).

In principle, different connectors cannot be mixed, but the optical fiber end faces of PC, SPC and UPC are flat and different in grinding quality. Therefore, the mixed connection of PC, SPC and UPC will not cause permanent physical damage to the connector.

APC is completely different. Its end face is ground to an 8 degree angle to reduce reflection. Its industrial standard return loss is - 60dB. APC connector can only be connected with APC. Because the structure of APC is completely different from that of PC, if the two connectors are connected by flange, the fiber end face of the connector will be damaged.

The way to connect APC to PC: through the optical fiber jumper of PC to APC conversion. In addition, it should be noted that the APC connector is usually green (while the yellow optical fiber is only single-mode optical fiber), and the tilt of the end face of the optical fiber can be seen by the human eye. The PC connector is usually blue.

Therefore, in order to avoid confusion in the use of connectors during the experiment (to avoid damaging input ports such as spectrometer), we should uniformly require the manufacturer to provide APC connectors when purchasing lasers, jumpers, etc. in the future.

FC/PC FC/UPC FC/APC can be connected in a mixed way, and the signal attenuation will not be large. According to the national standard, the insertion loss should be less than 0.5dB. The application mainly depends on the type of adapter. Generally, more FC is used for communication ODF rack, more SC is used for equipment optical port, and more ST is used in LAN and radio and television.



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