In accordance with the invention, an optical multiplexer includes at least one reconfigurable add-drop unit that can add-drop one channel out of a large set by switching the light path through one of a set of fixed add-drop filters. Reconfiguration is done by switching from the add-drop filter path to...http://www.google.de/patents/US6035080?utm_source=gb-gplus-sharePatent US6035080 - Reconfigurable add-drop multiplexer for optical communications systems
