Another source of scattering is the collision of photons with the fiber's molecular structure. Because scattering becomes more significant when the size of these imperfections is comparable to the wavelengths of light propagating through the fiber, shorter wavelengths suffer from more scattering. Absorption Impurities in the fiber absorb optical energy. Extrinsic Sources of Attenuation Microbending Microbends are geometrical imperfections in the fiber. Macrobending Macrobends are larger fiber curvatures and imperfections that prevent the cladding from reflecting all light back into the core.
Longer wavelengths suffer more than shorter wavelengths.
Other Extrinsic Sources of Attenuation Cable manufacturing stresses and environmental effects can also cause attenuation. Dispersion Dispersion is the spreading of light pulses as they propagate through the fiber. This spreading afflicts digital communication with bit errors and analog communications with distortion and a higher noise floor. Bandwidth must be constrained to limit dispersion. To maintain signal quality, dispersion should be reasonably small compared to the duration of a bit.