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The contact method of optical fiber connector has three types, PC——Physic Contact, UPC——Ultra Physical Contact and the APC——Angled Physical Contact, the difference among them are return loss besides physical property, return loss PC<UPC<APC. PC is widely used in the telecom equipments, UPS is mainly used to the special equipments, while APC is applied to radio, television and early CATV system.

SM stands for single optical fiber of 9/125um, MM refers to multimode optical fiber, including 50/125um,62.5/125um and 100/140um.

The optical fiber can be divided into FC、SC、ST、LC、D4、DIN、MU、MT type according to connector structure.

FC is the abbreviation of ferrule connector, it means the outside enhanced method is adopting metal sleeve, the fastening way is turnbuckle, this connection structure is simple, easy to operate, however it is easy produce Fresnel reflection and is difficult to improve the return loss performance, later, the using of physic contact (PC) improve the inserting loss and return loss greatly.

SC is rectangular in shell, the contact type and sleeve structure and size is same with FC, the fastening way is push-pull pin latch without rotation. SC connector has characters of low cost, low inserting and extracting force, low inserting loss, high compressive strength and high mounting density.

ST and SC interface are two types for optical fiber connectors, for 10Base-F connection, the connector is usually ST type, for 100Base-FX, in most case is the SC type.

Started from MT connector developed by NTT, MT-RJ has the same latch mechanism with the RJ-45 type LAN electrical connector, and direct to optical fiber by the guide pin assembled on the two sides of the small sleeve, which is convenient to connect the optical transceiver machine. The ended fiber is double-core arrangement design of 0.75 spacing, which is the high-density optical fiber connector to transmiss data.

LC connector are developed by the famous Bell Institute of Research and Development, its latch mechanism is modular jack (RJ) which is easy to operate, the size of the pins and sleeves are same with SC、FC, 1.25mm, which can increase the density of optical fiber.

MU (Miniature unit Coupling) connectors are the world smallest single-core optical fiber connector based on the SC-type connector and developed by NTT .This connector uses 1.25mm diameter of sleeve and the self-holding mechanism, its advantage is the realization of high-density mounting.