To understand DWDM Mux/Demux, you have to know what DWDM is. DWDM (Dense Wavelength Division Multiplexing) is an optical multiplexing technology used to increase bandwidth over existing fiber optic backbones. The data from various different sources is put together on optical fiber in which each signal travels at the same speed on its own light wavelength. In DWDM system, Mux/Demux are two indispensable modules. Mux (Multiplexer) is a module at the transmitter end that brings several data signals together for transporting over a single fiber, while Demux (Demultiplexer) is a module at the receiver end that separates the signals that come together and passes each channel to an optical receiver. DWDM Mux/Demux modules are made to multiplex multiple DWDM channels into one or two fibers. It can extend the bandwidth of optical communication network with low cost and long transmission distance, which makes it an ideal network solution.