Hi Stanimir,
Welcome to optisystem forum,May you tell me Which version of optisystem you are using?Because the system you have attched,i am not able to open it.For general discussion i would like to you to visit the optiwave samples if you are using latest version.There is example of WDM PON with AWG at 2.5Gbps.System is design very beautifully and you can easily understand the concept.I have also mention some links on discussion relative to your area of interest.Rest i will try your system using latest version and get back to you soon.
Regards