SFP Optical Module with PC/APC/UPC Optical Fiber Patch Cord

Fiber optic patch cord is an indispensable connection in fiber optic wiring. When choosing optical fiber patch cord, we always see the words PC/APC/UPC, such as LC/APC, FC/APC, SC/PC, ST/UPC optical fiber patch cord, etc. Do you know what PC/APC/UPC stands for? Are the SFP optical modules compatible with PC/APC/UPC optical fiber patch cords?

What is PC/APC/UPC?

PC/APC/UPC refers to different grinding modes of fiber optic connectors on fiber optic patch cord lines, and different grinding modes determine the fiber transmission quality, mainly reflected in return loss and insertion loss. So what's the difference between these three grinding methods?

1.What is PC?

PC (Physical Contact) is the most common grinding mode of fiber optic connector on optical fiber patch cord line, which is widely used in telecom operator equipment. Although the end face of the optical fiber connector looks like a plane, in fact, the end face is slightly curved and polished, and the highest point of bending is the center of the fiber core, which can effectively reduce the air gap between the fiber components. Generally, the return loss of the fiber hopper with PC grinding mode is -40dB.

2.What is UPC?

UPC(Ultra Physical Contact) is an evolutionary version of PC, which optimizes end face polishing to achieve better surface finish. Like PC, UPC has its highest bending point at the center of fiber core, but UPC has higher return loss than PC, generally at -50db (or even higher).It is commonly used on Ethernet network devices (such as ODF fiber distribution racks, media converters, and fiber optic switches), as well as in telephone systems.

3.What is APC?

APC (Angled Physical Contact) is the latest technology for the grinding of optical fiber end face. Its end face is angled at 8 degrees, so that it is more accurate and can effectively reduce the reflection. The return loss is about -60dB.APC is commonly used in optical RF applications with CATV equal wavelength range.

Note: return loss (reflection loss) refers to the reflection caused by impedance mismatching in the optical fiber link, which is the reflection of a pair of lines themselves. This percentage of reflected light is usually represented as -dB, and the higher the value, the better.

What is the difference between PC/APC/UPC?

After the above detailed introduction of PC/APC/UPC, you will find that PC/APC/UPC has differences in terminal face, return loss, application and other aspects.

Both PC and UPC are flat interface types. PC is the earliest grinding mode with poor return loss. UPC is based on PC structure evolution, its return loss is better than PC;APC is a grinding method with an 8-degree Angle on the end face, which can effectively reduce reflection and return loss. Compared with PC and UPC, APC is better and more suitable for high-bandwidth and long-distance links.

How to correctly select PC/APC/UPC optical fiber patch cord for SFP optical module?

As is known to all, the SFP optical module has two ports for transmission channels, one for sending signals and the other for receiving signals. Usually, the signal transmission needs to be realized through optical fiber patch cord. The above mentioned PC/APC/UPC optical fiber patch cords with different grinding types, can these three optical fiber patch cords be used together with the SFP light module? In fact, it is not. Because the connection port of SFP optical module is flat, it can only be connected with the optical fiber patch cord of PC and UPC. If it is connected with the optical fiber patch cord of APC, it will cause invalid connection or network failure.

In principle, the fiber optic connectors of PC/APC/UPC with three different grinding modes cannot be interlinked. However, since the fiber optic end structures of PC and UPC are flat (with slight bending), they are compatible and interchangeable, but there will be polishing quality problems, without any damage to the connector. Although the SFP light module can be connected with PC and UPC optical fiber patch cord, it is recommended to use the SFP light module with UPC optical fiber patch cord in order to ensure the good performance of the fiber link.

The optical fiber terminal structure of APC is completely different from that of PC and UPC, so APC cannot be interconnected and compatible with them. If forced connection, it will cause damage to the connector. If you want to connect the APC and UPC/PC, you must pass the APC-UPC/APC-PC convert optical fiber patch cord wire connection between them. But considering the waste of resources and the difficulty of wiring and other reasons, you are not suggested to do so. Do not use the SFP optical module on the APC optical fiber patch cord unless the SFP optical module specification on allowing APC optical fiber patch cord. It is recommended that you use the UPC optical fiber patch cord.

Conclusion

In a word, PC and UPC optical fiber patch cords can be used in Ethernet devices such as optical fiber switches and used together with SFP optical modules. APC optical fiber patch cord is mainly used in FTTx, PON and WDM. It is better not to be used with SFP optical module. The choice depends on what the network needs.