A technology for achieving extremely high data rates over fiber-optic cabling. Also known as wave division multiplexing (WDM), dense wavelength division multiplexing (DWDM) will likely replace time-division multiplexing (TDM) as the standard transmission method for high-speed fiber-optic backbones in the next few years.
Graphic D-15. Dense wavelength division multiplexing (DWDM).
DWDM modulates multiple data channels into optical signals that have different frequencies and then multiplexes these signals into a single stream of light that is sent over a fiber-optic cable.
Each optical signal has its own frequency, so up to 80 data streams can be transmitted simultaneously over the fiber using only eight different light wavelengths.
In addition, each data stream can employ its own transmission format or protocol. This means that, using DWDM, you can combine Synchronous Optical Network (SONET), Asynchronous Transfer Mode (ATM), TCP/IP, and other transmissions and send them simultaneously over a single fiber.
At the other end, a multiplexer demultiplexes the signals and distributes them to their various data channels.
Devices that support DWDM are more costly because the laser light sources for generating signals over fiber must be highly stable.