How to Test Fiber Splice Loss

When we talk about the methods of testing splice loss, many people would take OTDR (Optical Time Domain Reflectometer) as the best fiber optic equipment to test splice loss. But instead, OTDR is not specifically used to test splice loss. If you use OTDR to test splice loss, the measured loss value will be inaccurate. So in this article, we will talk about how to test splice loss.

Why OTDR is not specifically used to test splice loss?

Firstly, after a fiber is fused, if it is a long distance fiber, the splice loss will be too low for the OTDR to detect on the splice point. Secondly, even if there is a high loss point detected on the fiber, it may be caused by error operation, that is to say the fiber is not spliced correctly. After calibrating the arc, you can clean the fiber and re-splice the fiber.

OTDR 3000 testing

The right step to measure splice loss is as follow:

  1. Take out a length of optical fiber.
  2. Use a Light Source on one side, and an Optical Power Meter on the other side, to measure the loss of this fiber.
  3. Cut the optical fiber into two pieces

4.Use Fiber Fusion Splicer to splice the two pieces of the optical fiber.

BD-FS-41B Optical Fiber Fusion Splicer

5.After splicing, use Light Source and Optical Power Meter to measure the fiber loss again.

After Splicing

  1. The subtraction of the two fiber loss values will be the real splice loss of the fiber.


  1. You should use high precision Light Source and high precision Optical Power Meter, or the value would be inaccurate.
  2. You should keep the output power of Optical Light Source stable and in the same value.

Baudcom offers all types of fiber optic test equipment and fusion splicers. For more information, please feel free to contact us.

Post time:2023-07-07


Lomoveishiy – Finland

I needed those to connect my PC on the third floor to have internet access in that room, and ISP installed their modem on the first floor only. After dropping fiber patch cables, plugged in all cables into these media converters at both sides, and link came up instantly. Was much easier than I thought!

Raymond – USA

Great experience – units worked straight out of the box – just needed plug in cables and we were done. I also like the possibility to enable jumbo frames, while we do not have a need for this feature at the current moment it’s great to have this option.

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