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10 Most Common Causes of Loss in a Fiber Optic Connection

Optical Time-Domain Reflectometers are used by technicians to test the integrity of fiber optic cables. These instruments need to be durable for use in the field, easy to use, and powerful enough to determine if there is a bend or break in a fiber optic cable.

Here are the top ten ways in which loss can occur in a fiber optic cable.

1. Backhoe Fade (aka JCB Fade) occurs when construction equipment, such as a Backhoe, accidentally severs a fiber optic cable. This creates an instant loss of connection due to a sudden break when the fiber is dug up or damaged by the machinery.

2. Attenuation Fade occurs when there is a reduction of signal amplitude, to the extent that the signal becomes too weak to travel. Attenuation fade can be caused by light absorption, where the light is absorbed by the fiber itself, and scattering, where the light is scattered by irregularities in the glass structure.

3. Bend Loss occurs when the fiber optic cable is handled improperly and is literally bent. This can be caused at any point in the handling of the cables, from manufacturing to the laying of the cables, to environmental factors such as temperature and humidity.


4. Splice Loss occurs when fiber optic cables are not spliced perfectly. This type of loss can be avoided with proper handling of fiber optic cables and high-quality fusion splicing.

5. Over-Amplification occurs when the receiver is overwhelmed by too much signal, and can no longer function properly.

6. Dispersion Loss occurs when the signal’s frequency components get “smeared” due to the different speeds at which they travel through the fiber.

7. Loss of Timing causes loss when the frequencies between the receiver and transmitter are not aligned. Occasionally the phase-locked loop (PLL) system used to ensure that both ends are aligned will glitch.

8. Cosmic radiation can cause loss when a fiber is exposed to high radiation for an extended period of time, and the fiber’s Radiation-Induced Attenuation (RIA) accumulates. This occurs as the electrons are trapped in the glass due to ionizing radiation. The fiber optic cables may fully recover from this type of loss.


9. Polarization creates loss when a fiber is carrying a polarized signal is rotated or manipulated, and the receiver is dependent on that polarization.

10. Imperfections in the fiber can interrupt the signal and cause loss. Examples include: an air gap between fiber ends, a mismatch of core sizes, a deviation between the fiber axis directions, or a parallel offset of the fiber cores.

View TTI’s full range of powerful OTDRs and quickly and easily find the loss in your fiber optic networks, so you can keep your networks running smoothly and your customers happy.


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