DWDM technology is one of the applications of WDM technology. DWDM technology (Dense Wavelength Division Multiplexing) is capable of combining multiple optical wavelengths for transmission with a single optical fiber. It's used to increase bandwidth on existing fiber optic backbone networks. Moreover, it is to multiplex the tight spectral spacing of a single fiber carrier in a specified optical fiber to utilize the achievable transmission performance (for example, to achieve the minimum degree of dispersion or attenuation). So that to reduce the quantity of optical fibers under a certain information transmission capacity.
With the upgrading and updating of technology, the wavelength interval of WDM technology has changed from 20nm to a few nanometers, is getting smaller and smaller, so DWDM technology is also called dense wavelength division multiplexing technology.
The wavelength range of DWDM technology is 1525nm-1565nm (C band) and 1570nm-1610nm (L band). It is a small section taken from the CWDM wavelength range. The commonly used one is 1525nm-1565nm (C band), wavelngth interval is 0.8nm. DWDM channel has different intervals such as 0.4nm, 0.8nm, 1.6nm, etc.
Different from CWDM technology, the working wavelength of DWDM technology can reach from twenty to one hundred and sixty, save more fiber resources. But it need for additional wavelength control devices which makes price much higher.