Gracyfiber OADM split or insert one or more wavelengths from a multi-wavelength channel. In the optical transmission path, OADM can realize uploading and downloading of WDM signals without photoelectric conversion, and is one of the important devices in the key nodes of WDM optical network; OADM can play a role in its flexible networking, easy network upgrade and scale expansion etc. It is widely used in local area network (LAN), metropolitan area network (MAN) and other fields