The slope of fiber loss, stated in dB per kilometer at a given wavelength. Typical cabled values are about 0.35 dB/km at 1310 nm and 0.2 to 0.25 dB/km at 1550 nm for singlemode, and about 3 dB/km at 850 nm and 1 dB/km at 1300 nm for multimode. It is used in loss budgets and read straight from the slope of an OTDR trace between events.
Spec allows 0.4 dB/km and the OTDR slope is reading 0.33, so the attenuation coefficient passes on both reels.
Also heard as
- attenuation rate
Related terms
Attenuation
The gradual loss of optical power as light travels along a fiber, expressed in decibels.
Loss budget
The calculated total loss a fiber link should have, built from fiber length, connectors and splices.
Trace
The graph an OTDR produces, plotting returned power in dB against distance along the fiber.
Window
A wavelength region where fiber loss is low enough to run links, such as 850, 1310 or 1550 nm.
OS2
Optical Singlemode 2: the low-water-peak cabled singlemode grade used for most indoor and outdoor singlemode installs.