Welcome to OPtisystem,I think DFB laser is there in optisystem samples.Optisystem V13 samples
Component library>Transmitters>DFB laser
However this is my reference to only DFB laser,i am not exactly sue about doped fiber based DFB.Optiwave support can give you the right answer.Damian can help you out better.
Check out 2nd section of this tuturial
http://staging.optiwave.com/resources/latest-news/new-version-optisystem-13-0/