Dense Wavelength Division Multiplexing (DWDM) is a technique that multiple signals are carried together as separate wavelengths (color) of light in a multiplexed signal. DWDM is a variation of Wavelength Division Multiplex (WDM) but with much higher bandwidth and density. Using DWDM, up to 80 (and theoretically more) separate wavelengths or channels of data can be multiplexed into a lightstream transmitted on a single optical fiber. Each channel carries a time division multiplexed (TDM) signal. Each channel can carry up to 2.5 Gbps, there fore up to 200 billion bits per second can be delivered by the optical fiber simultaneously.

Another important feature of the DWDM system is that different data formats can be transmitted at different data rates can be transmitted together. Specifically, Internet (IP) data, Synchronous Optical Network data (SONET), and asynchronous transfer mode (ATM) data can all be travelling at the same time within the optical fiber. At the end of the transmission, each channel is demultiplexed back into the original source. Hence carriers can quickly introduce ATM or IP without having to deploy an overlay network for multiplexing. DWDM is a crucial component in today's optical network and widely deployed by Service Providers in their backbone network.

DWDM: Dense Wavelength Division Multiplex and Multiplexer

Related Terms: TDM, WDM, Multiplexer, SONET, IP, ATM

Reference Links: http://www.cse.ohio-state.edu/~jain/cis788-99/ftp/dwdm/: Optical Networking And Dense Wavelength Division Multiplexing (DWDM)