In order to provide customers with high-quality fiber optic jumpers, manufacturers conduct a series of tests during the design and manufacturing process. These fiber optic patch cord tests are crucial for any type of fiber optic network. Not only suppliers, but also end users need to understand the testing of these fiber optic jumpers in order to better judge the quality of fiber optic jumpers and ensure the feasibility of their applications. This article will introduce four types of testing: 3D testing, insertion loss (IL) testing, return loss (RL) testing, and end face testing. The fiber optic patch cords that have typically undergone these four tests have excellent quality and can be used with confidence by end users.
3D testing: guarantee of high-quality connector end face
3D testing is a key test to ensure the performance of fiber optic connectors. When producing fiber optic jumper components, suppliers will use a 3D interferometer (an optical interferometry measuring instrument) to inspect the fiber optic connector end face and strictly control the size of the connector end face. 3D testing mainly measures curvature radius, vertex offset, and fiber height. The details are as follows:
Curvature radius
The radius of curvature refers to the radius from the core axis to the end face, as shown in the figure below, which is the curve radius of the end face of the ferrule. The curvature radius of the end face of high-quality fiber optic jumper connectors should be controlled within a certain range. If the curvature radius is too small, it will exert significant pressure on the optical fiber, while if the curvature radius is too large, it will not be able to exert pressure on the optical fiber, resulting in an air gap (i.e. air gap) between the connector and the end face of the optical fiber. Whether the curvature radius is too large or too small, it can lead to insufficient light scattering or physical contact, which cannot guarantee optimal transmission performance. Only an appropriate curvature radius can ensure correct pressure application and optimal transmission performance.
Apex offset
Vertex offset refers to the distance from the highest point of the polished insert end face curve to the axis of the fiber optic core. This is a key item in the polishing process, and inaccurate polishing can lead to vertex offset.
In technical standards, it is generally required that the vertex offset of fiber optic jumpers is ≤ 50 μ M. If the top offset is large, an air gap will be formed, resulting in high insertion loss (IL) and return loss (RL) of the fiber optic jumper. In an ideal situation, the vertex offset of PC and UPC fiber optic connectors is almost zero, as they align the ferrule end face perpendicular to the polished surface and the vertex coincides with the fiber core axis during the polishing process. However, for APC type fiber optic connectors, their end faces are at an angle of 8 degrees to the fiber axis and are not completely perpendicular.
Fiber height
The height of the optical fiber is the distance from the end face of the optical fiber to the cross-section of the insertion core, which is the extension height from the fiber core to the end face of the ferrule. Similarly, the height of the optical fiber should not be too low or too high. If the height of the optical fiber is too high, it will increase the pressure inside the optical fiber when docking two optical fiber connectors, thereby damaging the optical fiber; If the height of the optical fiber is too low, there will be gaps when docking two optical fiber connectors, leading to increased insertion loss. This must be avoided for transmission with strict requirements for insertion loss.