| 摘要 |
<p>The invention concerns an optical add-drop filter for use in a communication system (500). The system (500) is capable of communicating both supervisory traffic and communication traffic. In the system (500) communication traffic is modulated onto first radiation occupying a first range (225) of radiation wavelengths, and supervisory traffic is modulated onto second radiation occupying a second range (250) of radiation wavelengths. When the first and second radiation is received at one or more of the nodes, it is then filtered in the add-drop filters associated therewith to isolate add channels, drop channels, a supervisory channel drop and a supervisory add from primary relatively-low attenuation paths of the filters (510, 700); the add channels, the drop channels, and the supervisory channel drop and add are then isolated at secondary paths associated with but not included in the primary paths.</p> |
