Differences Between PC, APC and UPC Connectors
Hello everyone. Today I will introduce three types of connectors and the differences between them. Let’s get started.
PC Fiber Optic Connectors
PC fiber optic connectors refer to connectors that are polished in physical contact. It is the most common type of polish on OM1 and OM2 multimode fibers. The PC fiber optic connector is created to overcome the air gap between the two surfaces by overcoming the tiny imperfections in the original flat fiber optic connector. In the PC fiber connector design, there is a slightly cylindrical conical head designed to eliminate the air gap, so the typical return loss in single mode applications is about -40dB, which is higher than the return loss of the original flat polished style (-14 dB or about 4%). Until now, this polishing style was outdated and evolving – the UPC polishing style came into being.
UPC Fiber Optic Connectors
UPC is an acronym for Ultra Physical Contact. This is an improvement over PC fiber optic connectors, with better surface finish after prolonged polishing and better return loss than PC construction, approaching -50dB or higher. Although it has relatively low back reflection compared to PC connectors, it’s not as robust. Be aware that repeated connection and disconnection will result in reduced surface quality and eventual performance.
APC Fiber Optic Connectors
In pursuit of low back reflection, APC fiber optic connectors were developed. APC refers to an angled physical connection with a ferrule end face radius polished at an 8° angle to minimize back reflections. Due to the addition of the sloped end face, the reflected light will leak into the cladding instead of staying in the fiber core. It should be noted that APC connectors can only mate with other angle-polished connectors, not non-angle-polished connectors, which will cause high insertion loss. The optical return loss of APC connectors is -60dB or higher, which is superior to other types of connectors.
PC vs UPC vs APC: What’s the Difference Between Them?
Having defined the three connector types, you will find that PC, UPC and APC connectors differ in many ways. Their differences in appearance, performance, and application categories are listed below.
1. Appearance
In terms of appearance, the main difference is the fiber end face. Although the end faces of the UPC are slightly curved, both the PC connector and the UPC connector are polished without an angle. Instead, APC connectors have 8° angled end faces. Another obvious difference is the color. The finish style of the connector can be distinguished by the color of the connector body. Take the FS LC APC single-mode fiber patch cord as an example, the connectors at both ends of the fiber are green. For LC UPC single-mode fiber patch cords, the connector is usually blue. This is also an easy way to differentiate these connectors.
2. Performance
Low insertion loss used to be difficult to achieve with APC connectors due to the air gap in the apex offset, but today improvements in connector design and manufacturing push APC connectors to perform better. The insertion difference between APC and UPC has been reduced. As for return loss performance, you may have noticed that APC connectors have the lowest back reflections of all the fiber optic connectors mentioned above due to the sloped end face. Therefore, the value of return loss is different. According to industry standards, the return loss of PC, UPC and APC connectors is about -40dB, -50dB and -60dB or more, respectively. The higher the return loss, the lower the reflection and the better the connector performance. Demonstrated the higher performance of the APC connector among the connectors listed.
3. Application
Since some applications are more sensitive to return loss, in these areas, for example, in the higher wavelength range, APC connectors such as for RF video signals are preferred, especially FTTx applications as well as passive optical networks and other uses For high bandwidth WDM system applications, APC connectors are preferred over single-mode fiber wavelengths. For those applications where no particular attention is paid to return loss, a UPC or PC comes into play. PC connectors are commonly found in telecom operator equipment, while UPC connectors are popular in digital TV, telephone and data systems.
The above is all my introduction. If you have any questions you want to discuss, please leave a message.
