Hi aabid,
well aabid what i understand from the query u have made i presume u can’t stop an optical signal completely from transmission, the signals will be there even if u are able to do so. In case of WDM system which i am presuming u need to implement this logic has in any case all the signals present even after many stages of filtration. What u require is a suppressor ( controller ) which might help u in this case.
thanks and regards