An old article on the site, "Introduction to the Four Types of Fiber Optic Patch Cords," has listed the appearance differences of the four types of connectors. Here we go one step further from an engineering perspective: buckle structure, typical insertion loss, and adaptation scenarios to help you select the specific connector location.

Divide size first according to port density

The LC ferrule is about 1.25mm, which is half of the SC. The same 1U panel can accommodate more ports, so almost all data centers and SFP optical modules use LC. SC uses push-pull buckle, which is common on FTTH and ODF sides. ST is locked by a rotating bayonet, and is used in old parks and security areas. FC is fastened with screws and is resistant to vibration. It is often found on distribution frames and test instruments.

Typical insertion loss and return loss reference

The joint itself isn't everything, the quality of the grind is just as critical as whether it locks into place. The following are generally available reference levels.

  • Well-ground PC or UPC single-mode patch cords typically have an insertion loss of less than 0.3dB.
  • Due to the 8° bevel angle of the APC end face, the return loss can reach over 60dB.
  • If the buckle of FC or ST is not locked, the insertion loss fluctuation will be more obvious than that of LC and SC.

The actual value is strongly related to the grinding quality. EB-LINK factoryLC-LC single mode dual core jumperThe measured insertion loss will be marked one by one to facilitate acceptance comparison.

Scenario selection suggestions

It is safer to put the connectors back into the scene: LC is preferred for switches and modules, with high density and clear buckles; SC is used for home entrances and distribution frames, which is convenient for manual plugging and unplugging; FC is selected in situations where there is vibration or frequent measurements are required, because the screws are not easy to loosen.

Rely on when cross-type docking is requiredLC-SC single mode dual core jumperTransfer is more reliable than forced redirection. The essence of choosing a connector is to choose the density, locking method and maintenance habits. Draw the port diagram first and then determine the model.