What is Optical Fiber Connector?

The main function of the optical fiber connector is to quickly connect two optical fibers, so that the optical signal can be continuous to form an optical path. Fiber optic connectors are movable and reusable, and are also indispensable and the most used passive devices in current optical communication systems. The two end faces of the optical fiber can be precisely butted through the optical fiber connector, so that the optical energy output by the transmitting fiber is coupled to the receiving fiber to the maximum extent, and it is necessary to minimize the impact of its intervention on the system.

 

 

Core Component: Ferrule

Through the role of fiber optic connectors, the core component that affects the performance of the connector is the ferrule. The quality of the ferrule directly affects the precise center connection of the two optical fibers. The ferrule is made of ceramic, metal or plastic. Ceramic ferrules are widely used. The main material is zirconium dioxide, which has the characteristics of good thermal stability, high hardness, high melting point, wear resistance, and high processing accuracy. The sleeve is another important part of the connector. The sleeve plays an alignment role to facilitate the installation and fixation of the connector. The inner diameter of the sleeve is slightly smaller than the outer diameter of the ferrule, and the slotted sleeve tightens the two ferrules to achieve precise alignment.

 

In order to make the end faces of two optical fibers better contact, the ferrule end faces are usually ground into different structures.

(1) Physical contact (PC) refers to micro-sphere grinding and polishing. The ferrule surface is ground into a slightly spherical surface, and the optical fiber core is located at the highest point of bending, so that the two optical fiber end faces reach physical contact.

(2) Angled physical contact (APC) is called the physical contact of the inclined plane, and the end face of the optical fiber is usually polished into an 8° inclined plane. The 8° angled bevel makes the end face of the fiber more compact, and reflects the light to the cladding through its bevel angle instead of directly returning to the light source, providing better connection performance.

(3) Ultra physical contact (UPC) optimizes the polishing and surface finish of the end face on the basis of PC, and the end face looks more domed. The connection of connectors needs to have the same end structure. For example, APC and UPC cannot be combined together, which will cause the performance of the connector to degrade.

 

 

Basic Parameters: Insertion Loss, Return Loss

Due to the different end faces of the ferrule, the performance of the connector loss is also different. The optical performance of optical fiber connectors is mainly measured by the two basic parameters of insertion loss and return loss.

 

Insertion loss (IL) is the optical power loss caused by the connection. It is mainly used to measure the optical loss between two fixed points in an optical fiber.It is usually caused by the lateral deviation between the two optical fibers, the longitudinal gap in the optical fiber connector, and the quality of the end face. The smaller the value is, the better, and the general requirement should be no more than 0.5dB.

 

Return loss (RL) refers to the parameter of the signal reflection performance, which describes the power loss of the return of the optical signal. The larger the value is, the better. The typical RL value of the general APC connector is about -60dB, and the typical RL value of the PC connector is about -30dB.

 

 

Optical fiber connector can realize low loss connection between optical fibers or between optical fiber and cable, and effectively reduce the impact of optical fiber connection on signal.