Hello,
The modulation peak current parameters sets a limit on the modulating signal peak current. You may check the examples at the following link for more information. Also, refer to the component datasheet that can be accessed from the help button in the component property.
Note that The parameters Bias current and Modulation peak current are scale factors applied to the input electrical signal.
C:\Users\USERNAME\Documents\OptiSystem 16.0 Samples\Component sample files\Transmitters Library\Optical Sources\
Regards,
Ahmad