Introduction to common types and performance of fiber optic connectors

Optical fiber connector is a passive device that realizes the detachable connection between optical fibers and optical fibers, and connects the two end faces of optical fibers.

Under normal circumstances, optical fiber connectors can be plugged and unplugged more than 1000 times, have a long service life, and the tensile strength is generally not less than 90N, and can be used in the temperature range of -40°C to +70°C, with good performance .

At present, silicon-based and plastic materials are the common transmission media for optical fiber connectors, and the common types of connectors are FC type, SC type, LC type and so on.

Among the above-mentioned common models, the FC connector was first developed by NTT Corporation of Japan. Its external reinforcement method is a metal sleeve, and the fastening method is a turnbuckle, with high tensile strength. The FC connector can be used for single-mode fiber or multi-mode fiber. It has a simple structure, is convenient to operate, and is easy to make. However, its fiber end is sensitive to dust, and it is prone to Fresnel reflection and has a large return loss.

The SC type optical fiber connector is developed by NTT Corporation of Japan. Its shell is made of molded glass fiber plastic and is rectangular in shape by molding process. The structure size of the used pin and coupling sleeve is exactly the same as that of the FC type. Because it is fastened by the plug-in pin-bolt type, it does not need to be rotated, the plug-in operation is convenient, the price is low, the insertion loss fluctuation is small, the compressive strength is high, and the installation density is high.

The LC type connector was first developed by the famous American laboratory Bell. It is made of a modular jack (RJ) latch mechanism and is easy to operate. The size of the pin and sleeve used is only 1.25mm, which is an ordinary SC connector. , Half of the size of FC, etc., so it can increase the density of optical fiber connectors in the optical fiber distribution frame. For now, LC-type connectors have actually occupied a dominant position in single-mode SFF, and their applications in multi-mode are also growing rapidly.

In addition, according to the shape and degree of grinding of the end face of the optical fiber connector, the optical fiber connector can be divided into: PC (close contact) type, SPC (super close contact) type, UPC (extreme close contact) type and APC (angled physical contact) type. Contact) type, their return loss, that is, “at the optical fiber connection, the decibels of the ratio of the retroreflected light (scattered light continuously transmitted to the input end) relative to the input light” are: -35dB; -40dB; -55dB ; -65dB.

As the return loss is smaller, the reflected light has less impact on the light source and system. Therefore, among the above four, APC has the best performance and PC has the worst performance.