Optical fiber connector is a device for detachable (movable) connection between optical fiber and optical fiber. It precisely connects the two end faces of the optical fiber so that the light energy output by the transmitting fiber can be coupled to the receiving fiber to the maximum extent. And to minimize the impact on the system due to its intervention in the optical link, which is the basic requirement of optical fiber connectors. To a certain extent, fiber optic connectors affect the reliability and performance of the optical transmission system.
classification
Optical fiber connectors can be divided into common silicon-based optical fiber single-mode and multi-mode connectors according to different transmission media, as well as other optical fiber connectors such as plastics as transmission media; according to the structure of the connector, it can be divided into: FC , SC, ST, LC, D4, DIN, MU, MT, etc. various forms. Among them, ST connectors are usually used for wiring equipment, such as optical fiber distribution frames, optical modules, etc.; and SC and MT connectors are usually used for network equipment. According to the shape of the fiber end face, there are FC, PC (including SPC or UPC) and APC; according to the number of fiber cores, there are also single-core and multi-core (such as MT-RJ). Optical fiber connectors are widely used and have many varieties. In the actual application process, we generally distinguish according to the structure of the optical fiber connector. The following are some common optical connectors:
FC type optical fiber connector
This connector was first developed by NTT of Japan. FC is the abbreviation of Ferrule Connector, indicating that the external reinforcement method is a metal sleeve and the fastening method is a turnbuckle. At the earliest, FC-type connectors used flat contact (FC) for the mating end faces of the ceramic pins. This type of connector has simple structure, convenient operation, and easy manufacture, but the fiber end is more sensitive to fine dust, and is prone to Fresnel reflection, which makes it difficult to improve the return loss performance. Later, this type of connector was improved by adopting a pin (PC) with a spherical mating end surface, and the external structure did not change, which greatly improved the insertion loss and return loss performance.
SC fiber optic connector
This is an optical fiber connector developed by NTT Corporation of Japan. Its shell is rectangular, and the structural dimensions of the pins and coupling sleeves used are exactly the same as the FC type. Among them, the end face of the pin mostly adopts the PC or APC type grinding method; the fastening method is the plug-in bolt type, without rotation. This type of connector is cheap, easy to plug and unplug, small fluctuations in insertion loss, high compressive strength, and high installation density.
ST and SC interfaces are two types of optical fiber connectors. For 10Base-F connections, the connectors are usually ST type, and for 100Base-FX, the connectors are mostly SC type. The core of the ST connector is exposed, and the core of the SC connector is inside the connector.
Double cone connector
The most representative product of this type of optical fiber connector was developed by Bell Laboratories in the United States. It consists of two precision molded cylindrical plugs with frusto-conical ends and a double-cone plastic sleeve inside. The tube is composed of coupling components. DIN47256 optical fiber connector is a connector developed by Germany. The structure size of the pin and coupling sleeve used in this connector is the same as that of the FC type, and the end face treatment adopts the PC grinding method. Compared with the FC type connector, its structure is more complicated. The internal metal structure has a spring to control the pressure, which can avoid damage to the end surface due to excessive insertion pressure. In addition, the mechanical accuracy of this connector is high, so the insertion loss value is small.
MT-RJ type connector
MT-RJ started from the MT connector developed by NTT. It has the same latch mechanism as the RJ-45 LAN electrical connector. The guide pins installed on both sides of the small sleeve are aligned with the optical fiber to facilitate the transmission and reception of light. It is connected by machine, and the end face of the connector has a dual-core (0.75mm spacing) arrangement design. It is a next-generation high-density optical fiber connector mainly used for data transmission.
LC type connector
The LC connector is researched and developed by the famous Bell Research Institute, and is made of a convenient modular jack (RJ) latch mechanism. The size of the pins and sleeves used is half the size of ordinary SC, FC, etc., which is 1.25mm. This can increase the density of optical fiber connectors in the optical fiber distribution frame. At present, in terms of single-mode SFF, LC-type connectors have actually occupied a dominant position, and their applications in multi-mode have also grown rapidly.
MU type connector
MU (Miniature unit Coupling) connector is the world's smallest single-core optical fiber connector developed by NTT based on the most used SC connector. The connector uses a 1.25mm diameter sleeve and self-retaining mechanism, and its advantage is that it can achieve high-density installation. Using MU's 1.25mm diameter sleeve, NTT has developed the MU connector series. They have socket type connectors (MU-A series) for optical cable connection; backplane connectors with self-holding mechanism (MU-B series) and simplified sockets (MU-SR series) for connecting LD/PD modules and plugs Wait. With the rapid development of optical fiber networks towards greater bandwidth and greater capacity and the widespread application of DWDM technology, the demand for MU connectors will also grow rapidly.
MC connector
In 2012, a domestic communications company independently developed a MC connector that is smaller and denser than the LC connector. Sunsea MC optical fiber connector is a high-density single-core optical fiber connector, suitable for various high-density occasions, such as large-capacity central computer room and high-density data center. The MC optical fiber connector has a high density, which can be up to twice the LC connector in the same space. It can be called the smallest and highest density connector in the world.
