DWDM (Dense Wavelength Division Multiplexing) An optical multiplexing technique defined in ITU-T Recommendations G.692 and G.959.1 as supporting eight or more wavelengths in the 1530–1565 nm C-band (Conventional band) and the 1565–1625 nm L-band (Long band). DWDM currently supports channel spacings of 200 GHz (1.6 nm at 1550 nm) and 100 GHz, with spacings of 50 GHz and even 25 GHz expected in the future. DWDM is used extensively in long haul networks. Coarse wavelength division multiplexing (CWDM) is defined by the ITU-T as supporting as many as 18 wavelengths in the 1270–1610 nm range, with spacing of 20 nm (2500 GHz at 1550 nm). See also CWDM, ITU-T, multiplexer, wavelength, WDM, and window. |