Hi Fayiqa Naqshbandi. Greetings.
Yes you are right. Yes we are able to implement two different modulation schemes for two different wavelengths or signals at the same time. I was in dilemma because i couldn’t find any paper mentioning so but luckily came across some journal in optical society of america where he has used two different schemes for two signals in the same system but it deals with encryption thing. Anyway thank you for showing some interest.
Regards
Atul Sharma