optical fiber jumpers
Why do Fiber Optic Patch Cord need to be polished? When a connector is installed on an end face of an optical fiber, return loss is inevitable, which is caused by the reflection of the light source. Severe light loss can damage the laser light source and interrupt the transmission signal. In order to allow the end faces of the two optical fibers to better contact, the end faces of the ferrule of the fiber jumper are usually ground into different structures.
What are the polishing methods for optical fiber jumpers? Generally, there are three types of polishing methods for fiber end faces: PC, UPC, and APC
PC (Physical Contact) means physical contact. PC is micro-spherical grinding and polishing, and the surface of the ferrule is ground into a slight spherical surface;
UPC (Ultra Physical Contact) is the super physical end face. UPC optimizes the end surface polishing and surface finish on the basis of PC, and the end surface looks more dome-shaped; APC (Angled Physical Contact) is the physical contact of the inclined surface. The fiber end face is usually polished to an 8° bevel.
What are the differences in the polishing method of jumpers?
①Color difference: APC connectors are usually green, and UPC/PC connectors are usually blue;
②Insertion loss: Insertion loss (InserTIon Loss) refers to the number of decibels of the output optical power relative to the input optical power after the optical signal passes through the fiber jumper. In general, the typical insertion loss of PC, UPC and APC connectors should be less than 0.3dB. Compared with APC connectors, due to the smaller air gap, UPC/PC connectors are usually easier to achieve low insertion loss;
③Return Loss: Return Loss, also known as reflection loss, refers to the number of decibels of the backward reflected optical power relative to the incident optical power at the connection point of the optical signal through the fiber jumper. Return loss is usually expressed as a negative dB value, and the higher the value of the parameter, the better. The return loss of the PC-polished fiber jumper is -40dB. The return loss of UPC is higher than that of PC, generally -55dB. The return loss of the APC industry standard is -60dB.
The return loss of the APC connector is better than the UPC connector, and the UPC connector is better than the PC connector
④ Application scenarios: PC is the most common polishing method for optical fiber connectors on optical fiber jumpers, and is widely used in telecom operators’ equipment;
UPC is usually used in Ethernet network equipment, digital, cable TV and telephone systems, etc.;
APC is generally used for optical radio frequency applications in the high wavelength range, and also used for optical passive applications, such as PON network structure or passive optical local area network
Since the end face of the APC is ground to an 8 degree angle, the APC cannot be connected to the UPC, which will cause the performance of the connector to decrease. However, the fiber end faces of PC and UPC are flat, and the difference lies in the quality of the grinding. Therefore, the mixed connection of PC and UPC will not cause permanent physical damage to the connector.
