Introduction of grinding method of fiber patch cord

Why should fiber optic patch cord be ground?

When a connector is installed on the end face of an optical fiber, the return loss is inevitable, which is caused by the reflection of the light source. Serious light loss will damage the laser source and interrupt the transmission signal. In order to make the end faces of two optical fibers contact better, the insert end faces of optical fiber jumpers are usually ground into different structures.

Generally, there are PC, UPC and APC grinding methods for fiber end face

PC (physical contact) is physical contact. The surface of PC microsphere is ground and polished, and the surface of insert core is ground into a slight spherical surface;

UPC (ultra physical contact) is the super physical end face. UPC is based on PC to optimize the end face polishing and surface finish, and the end face looks more dome like;

APC (angled physical contact) is the physical contact of inclined plane. Fiber ends are usually ground to 8 ° Slope.

What are the differences in grinding methods of optical fiber patch cord?

â‘  Color difference: APC connector is usually green, UPC / PC connector is usually blue;

â‘¡ Insertion loss: insertion loss refers to the decibels of the output optical power relative to the input optical power after the optical signal passes through the optical fiber jumper. In general, the typical insertion loss of PC, UPC and APC connectors should be less than 0.3dB. Compared with APC connector, UPC / PC connector is easier to achieve low insertion loss due to smaller air gap;

â‘¢ Return loss: return loss, also known as reflection loss, refers to the decibels of the backward reflected light power relative to the incident light power when the optical signal passes through the fiber jumper connection. The return loss is usually expressed as a negative dB value, and the higher the parameter is, the better. The return loss of PC lapping fiber jumper is - 40dB. The return loss of UPC is higher than that of PC, which is generally - 55dB. The return loss of APC industrial standard is - 60dB.

The return loss of APC connector is better than that of UPC connector, and UPC connector is better than PC connector

â‘£ Application scenarios: PC is the most common grinding method of optical fiber connector on optical fiber jumper, which is widely used in telecom operators' equipment;

UPC is usually used in Ethernet network equipment, such as digital, cable TV and telephone systems;

APC is generally used in high wavelength range of optical RF applications, but also for optical passive applications, such as PON network structure or passive optical LAN

Because the end face of APC is grinded into an 8 degree angle, APC can not be connected with UPC, which will lead to the performance degradation of connector. However, the fiber ends of PC and UPC are flat, and the difference lies in the quality of grinding. Therefore, the hybrid connection of PC and UPC will not cause permanent physical damage to the connector.


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