Designed based on wavelength division multiplexing technology, the wavelength division multiplexer is a kind of very popular fiber optic component. It serves to allow multiple selected signals to be placed on one fiber line, one signal being added at a time. Wide-ranging applications exist for WDMs, such as in the high-speed optical communication system, access network and all-optical network.
The wavelength division multiplexer is required in the dynamic monitoring of optical fiber cables for an optical network. As is shown in the figure below, the multiplexing unit has one input port and multiple output ports. The two most important devices in WDM systems are coarse wavelength division multiplexer, CWDM for short, and dense wavelength division multiplexer, DWDM for short.