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
(1) (Wavelength Division Multiplexing) A technology that uses multiple lasers and transmits several wavelengths of light (lambdas) simultaneously over a single optical fiber. Each signal travels within its unique color band, which is modulated by the data (text, voice, video, etc.). WDM has dramatically increased the carrying capacity of the fiber infrastructure of the telephone companies and other carriers. Also known as "dense WDM" (DWDM), vendors have introduced systems that can support hundreds of wavelengths, each carrying 10 Gbps. That means terabits of data per second can travel over one optical strand, thinner than a human hair. Contrast with TDM. See CWDM and fiber optics glossary. See also FDM.
(2) (Win32 Driver Model) A device driver architecture from Microsoft that consolidates drivers for Windows 95/98 and subsequent versions of Windows. It allows a hardware vendor to write one driver for its peripheral device that works with all 32-bit versions of Windows. See driver.