Dear Muhammad,
OPLL is best realized in OptiSPICE. Once it is built in OptiSPICE you can use it in OptiSystem using “OptiSPICE Output” component located in Default/Optiwave Software Tools/
I am attaching a good reference on a design for OPLL that you may try to build in OptiSystem.
Please contact me at ahmad.atieh@optiwave.com if you want to discuss more.
Regards,
Ahmad