wavelength division multiplexing
wavelength division multiplexing
(communications)The device that joins the signals together is known as amultiplexor, and the one that splits them apart is ademultiplexor. With the right type of fibre you can have adevice that does both and that ought to be called a "mudem"but isn't.
The first WDM systems combined two signals and appeared around1985. Modern systems can handle up to 128 signals and canexpand a basic 9.6 Gbps fibre system to a capacity of over1000 Gbps.
WDM systems are popular with telecommunications companiesbecause they allow them to expand the capacity of their fibrenetworks without digging up the road again. All they have todo is to upgrade the (de)multiplexors at each end. Howeverthese systems are expensive and complicated to run. There iscurrently no standard, which makes it awkward to integratewith older but more standard SONET systems.
Note that this term applies to an optical carrier (which istypically described by its wavelength), whereas frequency division multiplexing typically applies to a radio carrier(which is more often described by frequency). However, sincewavelength and frequency are inversely proportional, and sinceradio and light are both forms of electromagnetic radiation,the distinction is somewhat arbitrary.
See also time division multiplexing, code division multiplexing.