Wdm Definition

A multiplexing technique by which multiple wavelengths of light, or lambdas, share a single optical fiber.Wavelength division multiplexing is essentially frequency division multiplexing (FDM) at the optical level. Much as multiple electrical frequencies can coexist on an electrified copper circuit in support of multiple, simultaneous conversations in a FDM transmission system, multiple wavelengths can coexist on a single fiber of the appropriate type in a WDM system. A number of carriers now routinely deploy dense wavelength division multiplexing (DWDM) on fiber optic systems, introducing eight or more lambdas into an optical fiber through the use of tunable, cooled lasers firing through windows, or wavelength ranges.The ITU-T has defined 160 wavelengths at spacings of 100 GHz (at 1550 nm) and manufacturers currently offer DWDM systems that multiplex as many as 80 lambdas. Coarse wavelength division multiplexing (CWDM) is defined by the ITU-T as 18 wavelengths in the 1270
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