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What is UPC and APC in Fiber Optic?

APC and UPC are common polish types in fiber optic connectors. Installing a connector on a fiber optic end face inevitably results in return loss, if the optical sinal loss is severe, it will seriously affect the reliability and stability of fiber optic transmission. In order to ensure better contact between the end faces of two optical fibers, the ferrule end faces of fiber optic patch cords are usually ground into different structures, and UPC and APC are two widely used polish types.

APC and UPC

APC vs UPC

UPC

UPC, that is, Ultra Physical Contact. The end face of UPC connector is not completely flat, with a slight curvature to achieve more precise docking. UPC has optimized the end face polishing and surface smoothness on the basis of PC, making the end face appear more domed. Therefore, surface and performance optimize the return loss to -50dB or lower.

UPC

APC

APC refers to Angled Physical Contact. Unlike UPC connectors, the end face of APC connectors is precisely ground to an 8° angle, allowing most of the return loss to be reflected into the cladding instead of directly returning to the light source, providing better connection performance. The return loss of APC polishing type is better than that of UPC type, which can reach -60dB.

APC

What is the Difference Between APC and UPC

Color

APC and UPC are the two most common polish types of fiber optic connectors, which can be judged by the color of the connector. UPC connectors are usually blue, while APC connectors are usually green.

Fiber End Face

The significant difference between UPC and APC connectors lies in the fiber end face. UPC connector end face has a slight curvature that reflects light directly back to the light source, while the APC connector end face has an 8-degree angle that can reflect light at a certain angle to cladding layer, rather than directly returning to the light source.

Return Loss

Different polish types determine the quality of fiber optic transmission, the return loss is a parameter that reflects the signal reflection performance. If the return loss is low, better matching performance can be achieved. The return loss of UPC connectors is usually -50dB or lower, while the return loss of APC connectors can reach -60dB or lower.

Application Scenario

APC connectors are generally used in situations that require higher performance connections, as well as applications with high bandwidth and long-distance links, such as FTTx, passive optical networks (PON), and wavelength division multiplex (WDM). UPC connectors are commonly used in basic networks, including LAN, WAN, digital TV and telephony.

Conclusion

The choice between UPC or APC connectors depends on specific application requirements and compatibility of the fiber optic system. However, it should be noted that UPC connector and APC connector cannot be connected to each other. Due to the different ways in which the fiber cores are docked and contacted, the mixed use may cause optical link damage and other issues.

Gcabling provides various types of fiber optic connectors, fiber patch cords, etc. including APC and UPC type, with low loss and high cost-effectiveness, making it the best choice for optical communication wiring. If there is a need, please contact us.

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