In this article, we will try to describe the most common optical connectors that are used in data networks and television networks.
The fiber ferrule is a ceramic part of a cylindrical connector. An optical fiber is inserted into the center of the ferrule. It is used to pass laser radiation through two optical fibers.
The most common fiber ferrule diameters are 2.5 mm (in FC, SC, ST type connectors) and 1.25 mm (in LC type connectors).
SC Connector was developed by Nippon Telegraph and Telephone. The invention has become the most popular due to lower production costs.
Features and applications of SC connectors:
FC Connector was developed by Nippon Telegraph and Telephone. It was the first optical connector, that used a ceramic tip. This was the first optical connector that used a ceramic tip. It is not currently used due to the more popular SC and LC connectors.
Features and applications of FC connectors:
LC connector was developed by Lucent Technologies and released in 1997.
Features and applications of LC connectors:
ST Connector was developed in the United States by AT&T and used in professional environments: corporate networks, in the military field.
Features and applications of ST connectors:
Over the years, experts have upgraded the shape and characteristics of optical connectors, trying to achieve minimal losses and reflections on the connector. It is no secret that losses on the connector connection reduce the signal power, which leads to a decrease in the distance to which it can be transmitted. The reflected part of the signal can also introduce errors (BER) and heat the SFP module, which in turn reduces the quality of the transmitted information and leads to a reduction in the service life of the transmitting equipment.
That is why the types of polishing of optical connectors have been changed. The most popular types of optical connector polishing are PC (physical contact), UPC (ultraphysical contact), and APC (angular physical contact).
You can determine the type of connector/port polishing by its color:
The ferrule is beveled and processed on a flat surface. This avoids empty spaces between the tips of the connected connectors and provides losses in the range from -30 dB to -40 dB. This type is not relevant now.
UPC polished connectors are widely used in data transmission systems.They have a lower cost, then APC. Because of the low signal power in such systems, the reflected signal also has a low value. The connectors are similar to the PC type. Due to a clearer bevel curve, losses are reduced to the limit of -40 to -55 dB.
APC polished connectors provide less reflected signal towards the source.The surface of the ferrule is beveled at an angle of 8-9 degrees. Because of this, the signal is not reflected from the connector at a 180-degree angle, so the reflected signal does not return to the transmitter at all, or returns with less power. APC polished connectors are used in systems with a high-power signal. This is why they are common in cable TV and PON networks.