Fiber Optic Testing: Common Fiber Endface Problems

As network speeds increase, more and more optical fibers are used in our networks, and optical fibers also have to carry higher network speeds than before. In this case, those links that we once ignored are very likely to cause network problems, and one of the most important links is the problem of the optical fiber end face.

Among all the cases we received regarding fiber link test failures, as many as 95% of them were related to unclean fiber end faces. So how will these fiber end face problems appear in fiber link tests?

In actual fiber optic testing, especially high-speed fiber optic link testing, if the fiber end face is not clean, when doing OTDR testing of the link, the instrument will show that the reflection value is too high and phantoms are likely to occur.

What is more serious is that the dirty fiber end face will shorten the life of the fiber optic transceiver, and will also increase the bit error rate of the fiber optic transmission data, which will lead to an increase in network retransmission and a slower application experience. Therefore, in the high-speed fiber optic link test, the fiber end face detection link is very important.

Whether the end face of an optical fiber is clean cannot be seen with the naked eye. A fiber optic microscope is needed. So let's take a look at what the end faces of various optical fibers look like under a microscope.

Fiber Optic Testing: Common Fiber Endface Problems

As shown in the above figure, the leftmost picture is a good end face, which is clearly visible; the second picture is a fiber end face that has been gently touched by hand. Even if it is gently touched, we can see that it is also very dirty; the third picture is a stained fiber end face; the last picture is the fiber end face after being cleaned with alcohol. Nowadays, many people still use this habit of cleaning with alcohol, but is cleaning useful? If you don't check it with a microscope, you won't know that the fiber end face is still very dirty.

Therefore, if there is no microscope inspection, the optical fiber cleaning effect cannot be guaranteed even if it is cleaned, because it cannot be judged by the naked eye.

A dirty fiber end face will not only affect the data transmission of the fiber link, but also contaminate or even damage the clean fiber end face or device interface. We have encountered such a case, a clean fiber end face, the test result is passed, connected to a dirty fiber end face, and when you test it again, you will find that the clean end face is dirty. Therefore, develop good usage habits and formulate correct maintenance specifications to avoid such problems.

Fluke FI-3000 Fiber Optic Inspection Microscope

The Fluke FI-3000 Fiber Inspection Microscope offers a wide range of features that make it easy and efficient to test MPO fiber trunks. The multi-camera design provides a fast live view, allowing you to move from the entire trunk to each end face in real time using simple touch screen gestures. Automatically get a pass/fail result in just seconds. Save the results on your phone and share them via text or email, or use the industry-leading LinkWare platform to save a complete project report, including copper cable, fiber loss, OTDR and end face images*. The compact, ergonomic design and autofocus allow you to comfortably test hundreds of cables or ports.