Reply To: four level two electron material model

[Guilin Sun]

some more help can be found:

https://optics.ansys.com/hc/en-us/articles/360034394734-Advanced-and-custom-optical-material-models-in-FDTD-and-MODE

you can also check the original paper  Chang and Taflove, Optics Express, 2004, 3827-3833.

you should be able to modify the material properties based on the frequency you desire:

to create proper gain at the desired frequency.