Fiber optic interface standards

1) FC-type fiber optic connector: This type of connector was first developed by NTT in Japan. FC is the abbreviation for Ferrule Connector, indicating that its external reinforcement is achieved using a metal sleeve, and the fastening method is screw coupling. Initially, FC-type connectors used ceramic pins at their mating ends. Such connectors have a simple structure, are easy to operate, and straightforward to manufacture. However, the fiber end face is sensitive to dust, and Fresnel reflection tends to occur, making it difficult to improve the return loss performance. Later, improvements were made to this type of connector by using pins (PC) with spherical mating ends, while the external structure remained unchanged, which resulted in a significant improvement in insertion loss and return loss performance. (2) SC-type fiber optic connector: This is a fiber optic connector developed by the Japanese company NTT. Its housing is rectangular, and the structural dimensions of the pins and coupling sleeves used are exactly the same as those of the FC type. The end faces of the pins are usually ground using the PC or APC method ； The fastening method is a plug-and-latch type, requiring no rotation. Such connectors are inexpensive, easy to plug in and out, have low insertion loss variations, high compressive strength, and a high installation density. ST and SC interfaces are two types of fiber optic connectors; for 10Base-F connections, the connectors are usually of the ST type, while for 100Base-FX connections, they are mostly of the SC type. The core of the ST connector is exposed, while the core of the SC connector is inside the connector. (3) Biconic Connector: The most representative product among this type of fiber optic connector was developed by Bell Labs in the United States. It consists of two precisely molded, frustum-cone-shaped cylindrical plugs, along with a coupling component that contains a biconic plastic sleeve inside. (4) DIN47256 type fiber optic connector: This is a connector developed in Germany. The plug pins and coupling sleeve of this connector have the same dimensional specifications as those of the FC type, and the end faces are treated using PC grinding. Compared to FC-type connectors, its structure is more complex; it features springs within the internal metal structure to control pressure, thereby preventing damage to the end faces due to excessive insertion force. Furthermore, this type of connector has high mechanical precision, resulting in low insertion loss. (5) MT-RJ connector: The MT-RJ connector originated from the MT connector developed by NTT. It features the same latching mechanism as the RJ-45 LAN electrical connector. Optical fibers are aligned using guide pins mounted on both sides of a small sleeve. To facilitate connection with optical transceivers, the optical fibers on the connector’s end face are arranged in a dual-core configuration with a spacing of 0.75 mm. It is a next-generation high-density optical connector primarily used for data transmission. (6) LC-type connector: The LC-type connector was developed by the renowned Bell Research Institute, and it is constructed using a modular RJ latch mechanism that facilitates easy operation. The dimensions of the pins and sleeves it uses are half of those used in standard SC, FC, etc., at 1.25 mm. This can increase the density of fiber connectors in the fiber optic distribution frame. Currently, in the field of single-mode SFF, LC-type connectors have actually taken a dominant position, and their use in multi-mode applications is also growing rapidly. (7) MU-type connector: The MU (Miniature Unit Coupling) connector is the smallest single-fiber optical connector in the world, developed by NTT based on the SC type connector, which is currently the most widely used. This connector uses a 1.25mm diameter sleeve and a self-retaining mechanism, and its advantage is the ability to enable high-density installation. Using MU’s 1.25mm diameter sleeve, NTT has developed a series of MU connectors. They have socket-type connectors for optical cable connections (MU-A series) ； Bottom plate connectors with self-retaining mechanisms (MU-B series), as well as simplified sockets for connecting LD/PD modules to plugs (MU-SR series), etc. With the rapid development of fiber optic networks toward higher bandwidth and greater capacity, as well as the widespread use of DWDM technology, the demand for MU-type connectors will also increase rapidly.

All the optical cable terminal boxes exported by our factory use ST connectors; it is said that ST was chosen after consulting experts! If the device is not of type ST, use an optical fiber patch cable for conversion!