Hello,
Please check the examples in OptiSystem example library located at the following locations on OFDM and PON. You need to check both locations to design your OFDM-PON project.
C:UsersUSER NAMEDocumentsOptiSystem 20.0 SamplesMetro and access systemsPON and CDMA systems
C:UsersUSER NAMEDocumentsOptiSystem 20.0 SamplesAdvanced modulation systemsOFDM systems
Regards,
Ahmad