The main function of OADM is separated from the multi-wavelength channels or insertion of one or more wavelengths, there are fixed and reconfigurable two types.
◆ Fixed only up and down one or more fixed wavelength routing node is identified; the lack of flexibility, but the performance is reliable, small delay.
◆ Reconfigurable OADM node can dynamically adjust the wavelength of the upper and lower channels, enabling dynamic reconfiguration of optical networks, wavelength resources to get a good distribution network, but the structure is more complex array of available waveguide filter components, fiber grating structure different OADM structure, all with fiber optic technology can also be constructed OADM all-fiber structure.

But no matter what kind of structure OADM basic requirements are the same (insertion loss is small, the isolation between channels is higher, it is not sensitive to changes in ambient temperature and polarization, can tolerate the wavelength of the signal source within a certain range drift and jitter ) OADM during up and down the road, to be able to ensure power transfer between each channel remained the same. OADM operations should strive to be simple and convenient, can achieve high performance and low cost.

OADM in the network is a communications device, a communications device represents a network node. From the pass over business networks, and some need to get off at a network node, enter the network node for subsequent processing; some directly through the network node; and some need to be sent through the network node on the bus to go to the network. So OADM role is separate channel needs down the road and join a channel needs up the road, independent channel directly through.