The acronyms SC, LC, FC and ST refer to the most common types of optical connectors in FTTH applications and data networks. When choosing LC connectors, you may hear descriptions like LC UPC polished fiber optic connector or LC APC connector. Or when choosing a ST fiber optic patch cable, you can find the description like ST/ PC multimode fiber optic cable. What do these terms mean and what are the differences between these connectors?
Different Fiber Connector Types Introduction：
This article will simplify certain types of connectors and illuminate their differences for your better understanding.
PC, UPC and APC are acronyms for:
Physical Contact
Ultra Physical Contact
Angled Physical Contact
What is PC fiber optic connector?
PC (PHYSICAL CONTACT) FIBER CONNECTOR:
PC connector stands for the connector that is refined by physical contact. PC fiber connector is the most common type of polish observed on OM1 along with OM2 multiple mode fiber. The purpose of creating the PC fiber connector was to control the air space between two outward aspects from small defects in the actual plain fiber connector. In the configuration of PC fiber connector, there is to some extent a circular pyramid front with the purpose of getting rid of air space. For this reason, the usual reflection loss is around -40dB, which is more than the reflection loss of the actual plain polish technique. Now this polish technique has become outdated and its advanced UPC polish technique has been introduced.
What is UPC fiber optic connector?
UPC (ULTRA PHYSICAL CONTACT) FIBER CONNECTOR:
UPC is the abbreviation for ultra-physical contact. It is a developed form of the PC fiber connector with a stronger surface end after an increased refining and the reflection loss is good as compared to PC fiber connector, about -50Db or greater than that. Although it has a less back reflection comparatively, it is not as strong as sufficient. It should be noted that incessant links and detachments will become the cause of the decay of the exterior and final presentation.
What is APC fiber optic connector?
APC (ANGLED PHYSICAL CONTACT) FIBER CONNECTOR:
APC connectors were created beyond the activity of less back reflection. APC stands for Angled Physical contact, at an angle of 8° the ferrule edge surface area of which is made refined, reducing the back reflection subsequently. As a replacement for the remains in the core of the fiber, the reflected brightness will discharge into the covering as long as the angled edge surface is added. Instead of having a connection with non-angled refined connectors, APC fiber connectors should only be familiar with further angled refined fiber connectors, otherwise there will be great installation damage. APC fiber connectors have a reflection loss of -60Db or greater than this, which is good compared to other types of connectors.
PC vs. UPC vs. APC: What's the difference?
UPC vs PC
End face structure - The basic difference between UPC and PC is the structure of the end face of fiber connectors. The PC connector has an almost flat surface, while UPC looks like a more dome-shaped convex spherical surface.
Polish technology - UPC uses optimized extended polishing technology to give a better fiber surface finish than PC.
Return loss - The different structure and polish technology results in different performance of the return loss. The minimum return loss of the UPC connector is --50dB, while the PC connector is -40dB.
APC vs UPC
End face structure -- Similar to UPC and PC, the basic difference between APC and UPC is also their end face structure. The end face of the UPC connector is shaped as a flat-convex spherical without angle. Instead of flat, the APC connector end face is sloping, and the APC connector angle is 8 degrees. The 8-degree sloping surface allows a more accurate contact of two end face surfaces on two fibers, also efficiently reduces the back reflection by reflecting the light to the fiber cladding.
Appearance
In the expression of outward form, the main difference is the fiber edge surface. Although the edge surface of UPC has a small deflection, both PC and UPC fiber connectors are refined without any angle. APC fiber connector is preferably presented with an angle of 8° edge surface.
Color is another clear difference. In order to discriminate against the kind of Polish technique, which the connector presents by the color of the physique of the connector, the edges of APC connectors are often green. The connectors for an LC UPC SMF patch wire are usually blue. In addition, it is an easy way to determine the relevant connectors separately.
Performance
Formerly, it was found very difficult to attain less installation failure by utilizing APC fiber connectors for the sake of air space within the apex offsets, but these days the development in the formation of connector and production forces APC fiber connectors to show a good presentation. The difference in installation between UPC and APC has decreased.
As the functionality of reflection loss is considered, you might have observed that APC fiber connectors possess the cheapest back reflection among all the indicated connectors following the angled edge surface. On this basis, the advantages of reflection loss are of different kinds. According to the level of the manufacturing company, the reflection loss of APC, UPC and PC is sequentially around -60Db, -50Db and -40Db or greater. If the reflection loss is greater, the back reflection will be less and the functionality of the connector will be good. Among all the connectors mentioned, APC fiber connectors are of great value.
Application
APC fiber connectors are desired in certain ranges as few implementations are very touchy to reflection loss, for example in high-level wavelength reach as those utilized for video signs of RF, specifically FTTX implementations and for implementations like inactive optical systems and further WDM networks making use of high-level wavelength through SMF.
PC or UPC play a role for those implementations where the reflection loss is not given the required concentration. UPC fiber connectors are preferred in telegraphy, digital television and data networks, while PC fiber connectors are usually observed in the paraphernalia of telecommunications workers.
How to choose between APC and UPC?
Picking the right physical contact connector. Looking at current technology, it is clear that all of the connector end-face options mentioned in this blog post have a place in the market. If we take a sidestep across to Plastic Optical Fiber (POF) applications, this can be terminated with a sharp craft knife and performance is still deemed good enough for use in the high-end automotive industry.
When your specification also needs to consider cost and simplicity, not just optical performance, it is difficult to claim that one connector is better than the others. Therefore, whether you choose UPC or APC depends on your specific needs. For applications that require high-precision optical fiber signaling, APC should be the first consideration, but less sensitive digital systems will perform equally well using UPC.
Conclusion
It is not reasonable to suggest that the preferred fiber connectors are APC, UPC or PC. Connectors with physical contact (PC) polish style are not recommended for demanding and extensive applications. APC connectors are preferred for applications where maximum precision and minimum losses are desired. UPC connectors offer better performance than PC connectors. In terms of insertion loss, UPC connectors are superior to APC connectors. However, APC connectors are the best connector available, which is why they cost more than other types.