Dear Arjun,
What do you mean by MLL? is it mode-locked laser? If yes, you may check the examples in OptiSystem Example Library at the following link for guidance. If you need more information, please email me at ahmad.atieh@optiwave.com.
C:\Users\USER NAME\Documents\OptiSystem 18.0 Samples\Optical amplifiers\Fiber lasers and amplifiers
Regards,
Ahmad