Hello Atul Sharma,
I am not clear (understand) about the question and the line “Now my question is if the signal that is added by the add component is self modulated or i can change the different parameters of that signal”, Where you want to change the parameters.
As far as I have understood your query, Yes you can add a optical modulated signal using the Add or Drop Multiplexer and extract also the modulated signal and then demodulate it.
WDM Add and Drop multiplexer. Equivalent to a combination subsystem based on the WDM Add and WDM Drop components.
You can refer to one sample at the WDM systems folder named COADM.
Regards,
Dhiman