Power lost along a fiber, mostly to Rayleigh scattering from tiny density variations frozen into the glass, plus absorption by impurities and bending. Scattering falls steeply as wavelength increases, so singlemode fiber loses less at 1550 nm than at 1310 nm, and multimode less at 1300 nm than at 850 nm. Total link attenuation adds fiber loss to connector and splice losses.
Attenuation at 1550 is right where it should be, about 0.2 dB a kilometer, so the glass itself is fine.
Also heard as
- fiber loss
Do not mix it up with
- Insertion loss: Insertion loss is measured for a specific component or whole link, while attenuation describes loss built up along the fiber.
Related terms
Attenuation coefficient
Fiber loss per unit length, in dB/km, which sets how much a given length of glass will lose.
Backscatter
The small fraction of light scattered in the fiber that travels back toward the source, which OTDRs measure.
Macrobend
A bend in a fiber tight enough to see, which lets light escape the core and causes loss.
Microbend
A tiny, invisible deformation of the fiber axis caused by pressure, which scatters light out of the core.
Insertion loss
The optical power lost when a component or a whole link is placed in the light path, measured in dB.