DWDM

Dense Wavelength Division Multiplexing (DWDM) is the technology of choice for transporting extremely large amounts of data traffic over metro or long distances in telecom networks. Optical networking and especially the use of DWDM technology has proven to be the optimal way of combining cost efficient transport with advanced functionality, which can cope with the bandwidth explosion from the access network.
DWDM typically has the capability to transport up to 80 channels (wavelengths) in what is known as the Conventional band or C band spectrum, with all 80 channels in the 1550 nm region. DWDM takes advantage of the operating window of the Erbium Doped Fibre Amplifier (EDFA) to amplify the optical channels and extend the operating range of the system to over 1500 kilometers. This denser channel spacing requires tighter control of the wavelengths and therefore cooled lasers as opposed to Coarse Wavelength Division Multiplexing (CWDM) which has broader channel spacing un-cooled lasers.