Physical-contact connectors

Physical-contact connectors, sometimes referred to as butt-coupled connectors, have a polished end-face surface with a slight outward (convex) curvature. When inserted into the receptacle, the fibers are precisely aligned and touch each other, thereby allowing maximum light transfer and minimum return loss. The IBM® duplex connectors, the ST connector, the SC Duplex connector, the FC/PC connector, the MT–RJ connector, and the LC Duplex are types of physical-contact connectors.

IBM duplex connectors, which combine the transmit and receive signals in one housing, provide high reliability and have low loss characteristics. They are keyed to provide correct orientation and use release tabs to prevent accidental removal.

Some IBM duplex connectors and receptacles used for single mode fiber have additional keying. This prevents the plugging of multimode IBM duplex connectors into IBM products having single mode receptacles.

The SC Duplex connector is another type of connector which may be keyed to prevent accidental plugging of a multimode fiber into a single mode receptacle, and to provide correct orientation to the TRS.

The MT–RJ connector has distinct male ends (with metal guide pins) and female ends (with guide holes). Only male to female connections will transmit optical signals. Since all MT–RJ transceivers have a male interface, only female jumper cables are required for most installations.