Wavelength-Division Multiplexing uses multiple light wavelengths to increase the transmission capacity of fiber cables. There are two types of WDM systems in common use, providing dense (DWDM) and coarse (CWDM) granularity of wavelengths. WDM is a vital component of optical networks because it maximizes the use of installed fiber cable and allows new services to be provisioned quickly and easily over existing infrastructure. CWDM and DWDM technologies differ primarily in spacing of the wavelengths, the number of channels, and the ability to amplify signals in the optical space.
