Fiber optic connector is a device that allows detachable (movable) connections between optical fibers. It precisely connects the two end faces of the optical fibers to maximize the coupling of the optical energy output from the transmitting fiber to the receiving fiber, and minimize the impact on the system caused by its intervention in the optical link. This is the basic requirement of fiber optic connector. To some extent, fiber optic connectors affect the reliability and performance of optical transmission systems.

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 method is to use a metal sleeve and the fastening method is a screw buckle. Initially, FC type connectors used ceramic pins with planar contact (FC) on the mating end face. This type of connector has a simple structure, easy operation, and easy production, but the fiber end is sensitive to fine dust and prone to Fresnel reflection, making it difficult to improve the return loss performance. Later on, improvements were made to this type of connector by using pins (PC) with spherical mating faces, while the external structure remained unchanged, resulting in significant improvements in insertion loss and return loss performance.

SC type fiber optic connector

This is a fiber optic connector developed by NTT Corporation in Japan. Its shell 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 often polished using PC or APC grinding methods; The fastening method adopts a plug-in pin latch type, which does not require rotation. This type of connector is inexpensive, easy to plug and unplug, with small fluctuations in insertion loss, high compressive strength, and high installation density.

ST and SC interfaces are two types of fiber optic connectors. For 10Base-F connections, connectors are usually ST type, while for 100Base-FX, connectors are mostly SC type. The core of the ST connector is exposed, while the core of the SC connector is inside the joint.

Biconic Connector

The most representative product of this type of fiber optic connector was developed and researched by Bell Laboratories in the United States. It consists of two cylindrical plugs with precision molded truncated cone shaped ends and a coupling component with a double cone plastic sleeve inside. DIN47256 fiber optic connector is a connector developed in Germany. The structural dimensions of the pins and coupling sleeves used in this connector are the same as those of the FC type, and the end face treatment adopts PC grinding method. Compared with FC type connectors, its structure is more complex, and there are springs in the internal metal structure that control pressure, which can avoid damaging the end face due to excessive insertion pressure. In addition, this type of connector has high mechanical accuracy, resulting in lower insertion loss values.

MT-RJ type connector

MT-RJ started with the MT connector developed by NTT, which has the same latch mechanism as the RJ-45 LAN electrical connector. It aligns with the optical fiber through guide pins installed on both sides of a small sleeve. In order to facilitate connection with optical transceivers, the connector end fiber is designed with a dual core (0.75mm interval) arrangement, and is mainly used for the next generation high-density optical fiber connector for data transmission.

LC type connector

The LC type connector is developed by the renowned Bell Institute and is made using a modular jack (RJ) latch mechanism that is easy to operate. The size of the pins and sleeves used is half of the size used for ordinary SC, FC, etc., which is 1.25mm. This can increase the density of fiber optic connectors in the fiber optic distribution frame. Currently, LC type connectors have taken the dominant position in single-mode SFF, and their applications in multi-mode are also growing rapidly.

MU type connector

The MU (Miniature Unit Coupling) connector is the world's smallest single core fiber optic connector developed by NTT based on the most commonly used SC type connector,. The connector adopts a 1.25mm diameter sleeve and a self retaining mechanism, which has the advantage of achieving high-density installation. NTT has developed the MU connector series using MU's 1.25mm diameter sleeve. They have socket type connectors (MU-A series) for fiber optic cable connections; Bottom plate connectors with self retaining mechanisms (MU-B series) and simplified sockets for connecting LD/PD modules and plugs (MU-SR series). With the rapid development of fiber optic networks towards larger bandwidth and capacity, and the widespread application of DWDM technology, the demand for MU type connectors will also grow rapidly.

MC connector

In 2012, a domestic communication company independently developed an MC connector that is smaller in size and higher in density than LC connectors. The Rihai MC fiber optic connector is a high-density single core fiber optic connector suitable for various high-density applications, such as large capacity center data centers and high-density data centers. The MC fiber optic active connector has a high density, which can reach up to twice that of an LC connector in the same space, making it the smallest and highest density connector in the world.