ber-optic cable. In addition to the use of SMA and ST connec- tors, some manufacturers use proprietary designs. The latter obviously restricts interconnection capability. Table 3.3 provides an alphabetical list of common connectors used with glass fiber-optic cable. This list should Chapter Three not be viewed as all-inclusive as many additional proprietary connectors have been introduced by vendors since 1990. Insertion Loss The insertion of a connector results in a loss of optical power. We can determine that loss, which is referred to as insertion loss, by measuring power before and after the insertion of a connection. Thus, the inser- tion loss becomes dB = 10 log P2 TABLE 3.3 Connector type Description Connectors Com- monly Used with Biconic Uses a tapered sleeve fixed to the fiber-optic cable; when the plug is Glass-Based Fiber- inserted into a biconic receptacle, a tapered end provides a mecha- nism for locating the fiber-optic cable in an appropriate position Optic Cable (although one of the earliest connector types used with fiber optics, this cable is little used today) Originally designed by Nippon Electric Corporation, the D4 is simi- lar to the FC connector; it uses threaded coupling and a 2.0-mm-diam- eter ferrule The FC connector uses a position locatable notch and a threaded receptacle to provide extremely precise positioning for single-mode fiber-optic cable Uses a spring-loaded full-ceramic ferrule A Lucent developed small form connector that fits into a standard RJ-11 jack; LC supports both single- and multimode fiber Employs a push-pull coupling method with a locking tab; the SC con- nector is used mostly with single-mode fiber-optic cable Uses a threaded cap and housing; considered the predecessor of the ST connector (the SMA connector has been rapidly replaced by the use of ST and SC connectors) Uses a keyed bayonet coupler similar to a BNC connector (the ST con- nector is in widespread use and can support both single-mode and multimode fiber); there are two versions, referred to as ST and S