What is an APC connector and how is it measured?
The single-mode fiber connector we encounter most in our work is the one with the main body in blue, but if it is a passive optical network (PON), carrier network or very large-scale data center, you may encounter the main body as Green single-mode fiber connectors-These green connectors are used more and more.
Single-mode connectors use UPC (super spherical) fiber end faces, while green single-mode connectors use APC (oblique spherical) fiber end faces. It is very important to understand the difference between the two different colors and different fiber end faces. If the termination is incorrect, it may cause damage to the fiber and even damage the light source port of the device. For UPC connectors, the fiber end face is an approximately circular surface. In contrast, the end face of the APC connector is inclined at 8 degrees. This tiny angle allows the reflected light to be absorbed by the cladding, which reduces the back reflection in the core and provides excellent return loss performance.
Although for fiber optic links, we usually care about insertion loss, some applications are more susceptible to reflection (return loss). For example, high-power lasers used in long-distance fiber links are very sensitive to reflections, and severe reflections may even damage them. Fiber applications that operate at higher wavelengths (typically 1500 nanometers and above) are also more susceptible to reflection, including wavelength division multiplexing (WDM) applications that use multiple wavelengths to transmit signals, and use of RF signals at higher wavelength Applications for sending video include PON / GPON deployment.
These applications explain why we see APC connections deployed in service provider networks. As more and more corporate customers deploy PON for their LANs, more and more cable companies turn to optical fiber to provide broadband services, more data centers are connected to operator networks and longer single-mode fiber links are deployed With WDM applications, we are beginning to see more and more applications of APC connectors and more and more application environments.
It is important to note that the UPC and APC connectors cannot be docked. Not only will the cores not be aligned, resulting in severe performance degradation, but if you try to dock the two, you may damage the end faces.
When using APC connection to test a single-mode fiber system, you need to understand a few things. When performing a level 1 insertion loss test, Fluke Networks ’CertiFiber Pro only supports APC connectors at the input ports—the output ports use UPC connectors. Although no damage will occur, you will receive a warning from the tester that the received power is too low. The input port uses non-contact docking, so it can accept any type of connector. Therefore, when testing an APC system, you need two UPC-APC hybrid cables and two APC-APC cables to connect.
If you are using Fluke Networks FI-7000 FiberInspector Pro or FI-500 FiberInspectorMicro to check the APC connector, you need to use the APC probe tip (purchased separately). If you try to use the UPC probe tip to check the APC end face, you cannot focus on the core and end face. On the other hand, the geometry of the tip of the APC probe can be adapted to the 8-degree tilt angle of the APC end face, so the end face can be observed correctly.
If you want to know more, our website has product specifications for connector, you can go to ALLICDATA ELECTRONICS LIMITED to get more information