Fiber Optic Transmission Loss

What are the main sources of Optical Fiber transmission loss ?

Table of content

Contaminations

One of the largest factors in the loss of reliability
is the contamination of optical connectors end face.

Indeed, if there is dirt, dust, oil, and other debris on the core of the fiber, the light carrying the signal won't be able to pass through the connector. Therefore, the signal's bandwidths will be reduced, or worst won't be even transmitting at all!

To avoid such issues, there is multiple solution. Firstly, purchase a fiber cable in line with your needs. If it's a simple patch cord for a fix indoor connection or do you need a robust mobile solution such as the opticalCON for outdoor events?

Nevertheless, nothing is 100% effective. So once in a while, even with the best material, you'll need to clean the ferrules.
In order to do so, you can first inspect the ferrule condition, by using for example our Senko Smart Probe 2.

The last step would be to clean the ferrules using a dedicated fiber optic cleaner, removing the contamination and allowing the transmission of the signal as it should be.
Here are examples of tools that you can use to clean your fiber:

Senko Cassette Cleaner

Senko SmartCleaner 1.25mm

Senko MPO Plus Smart Cleaner

Senko Smart mini-Cleaner 2mm (Lemo 3K.93C)

Dispersion

The optical fiber dispersion describes the process of how an input signal broadens/spreads out as it propagates/travels down the fiber.

The modal dispersion is caused by the time difference between the fastest and the slowest mode of light entering the fiber at the same time and travelling a kilometre (max 1 to 3 nanoseconds).

The spectral dispersion depends only on the source, if we use a LED, which as 20 times more spectre compared to a laser, the spectral dispersion won't be eliminated.

Bending

The bending is attenuation caused by high-order modes radiating from the outside of a fiber optic waveguide which occur when the fiber is bent around a small radius.

Indeed, even the amazing Cleerline SSF Fiber technology has losses due to bending. Consequently, even with Cleerline SSF Fiber, you must untight your knot to make your fiber work properly.

Macrobending (major/visual angle) will cause light to leak out of the fiber, causing signal attenuation.(Minimum bending radius of a cable).

Microbending (small variations/bumps in the core to cladding interface) can cause high-order modes to reflect at angles that will not allow further reflection.

On average, the minimum radius curve equal to 20-30 times the diameter of the external cable.