Hello, everyone!
Today, I will start to write about testing the IL of optical cables. In this article, I will explain testing IL of installed optical cable or double-ended method.
All optic cables require IL (Insertion Loss) testing. Tests are done at the wavelengths that will be used in that telecommunications system. This testing includes the measurement of losses in optical fiber, fusion splices, optical connectors, etc. There are three methods of IL testing, it depends on the optical cable. A double-ended method is used to test the installed optical cable. A single-ended method is used for patch cords or shorter optical cables. The special test method is used for optical cables with different optical connectors, it requires three reference cables.
Testing IL of installed optical cable – double-ended method
As I said before, the double-ended method is used to test the installed optical cable. A test source, optical power meter, and launch and receive referent cables are required. Test source for MM fibers emits 850 nm and 1300 nm, for SM fibers emits 1310 nm and 1550 nm.
Figure 1. Double-ended method
Reference optical cables are tested cables, with 0 dB attenuation, that have the same fiber type and size as the installed optical cable for test and have optical connectors compatible with optical connectors of installed optical cable.
Before the testing, all optical connectors from the test source, optical power meter, and reference cables should be cleaned. There are many methods for cleaning optical connectors, we can use one-click cleaners for this procedure. The next step is connecting the reference cables to the test source and to the optical power meter. When connecting the reference cable to the test source, it is recommended not to disconnect, otherwise, the measurements will be incorrect.
Special methods are used to set 0 dB (referent methods), there are three options – with one, two, or three referent optical cables. Only after all of these procedures, we can start to measure. In figure 1, we can see this method for measuring installed optical cables.
During the measurement and the end of the measurement, documentation is made. It must contain the date of the test, the name of the operator, the equipment used for the test, the 0 dB setting method (referent method), the type of fiber, cable, and optical connector, the test wavelength, and the loss measured.
This is the end of this article. In the next article, I will continue to write about this topic >> Testing IL of optical cables (2).
Thank you!
