Attenuation is the gradual loss of signal strength along a fiber optic waveguide caused by absorption and scattering. It is typically measured in decibels, or dB, and is expressed per unit length, usually in dB/km. Attenuation is an important factor to consider when designing a fiber optic cable network, as it affects the signal quality and the maximum distance a signal can travel.

When light energy is propagated down a fiber optic cable, it will eventually suffer some amount of signal loss due to absorption and scattering. Absorption occurs when the light energy is absorbed by the material of the fiber core, while scattering is the result of variations in the refractive index of the core and cladding materials. These effects weaken the signal as it passes along the cable, resulting in an attenuated signal at the receiving end.

The amount of attenuation experienced by a signal is highly dependent on the material properties of the cable, and any bends or splices in the cable will further add to the attenuation. Different wavelengths of light also suffer different levels of attenuation, with longer wavelengths generally experiencing more signal loss. The amount of attenuation also increases with distance, as the signal is weakened over longer cable runs.

It is important to remember that attenuation is a natural and unavoidable consequence of transmitting signals through a waveguide. Simply put, the longer the cable and the weaker the signal, the more attenuation it will experience. It is therefore important to take this into account when designing a fiber optic cable network, as the amount of attenuation experienced by the signal will affect the signal quality and the maximum distance it can travel.