A novel add/drop optical filter providing arbitrary channel arrangements between two input WDM signals and two output WDM signals is presented. The device consists of two WGR's connected by a plurality of 2.times.2 optical switches and 3 db coupling devices in each WGR branch. Through use of the inventive...http://www.google.es/patents/US5566014?utm_source=gb-gplus-sharePatente US5566014 - Tunable add/drop optical filter providing arbitrary channel arrangements
