Every laser emits a small spread of wavelengths, and because glass index and waveguide effects vary with wavelength, those colors arrive at slightly different times. Standard singlemode fiber has zero dispersion near 1310 nm and about 17 ps/nm/km at 1550 nm. Over long 10G spans it limits reach unless compensated with dispersion-compensating fiber or modules, and coherent transceivers correct it digitally.
Link's 120 km of plain G.652 at 10G with no DCM, so chromatic dispersion is going to eat that budget before loss does.
A link with plenty of optical power that still throws bit errors over long distances is often a dispersion problem, not a loss problem.
Also heard as
- CD
Related terms
Singlemode fiber
Optical fiber with a core so small that light travels in a single path, used for long-haul, metro, FTTH and campus backbones.
Window
A wavelength region where fiber loss is low enough to run links, such as 850, 1310 or 1550 nm.
Lambda
A single wavelength channel on a fiber, named after the Greek letter used for wavelength.
WDM
Wavelength Division Multiplexing: sending several signals on different wavelengths over the same fiber.