Ok, thank you for the fast reply.
So if my material is silicon-rich silicon nitride I need to insert the desired third order susceptibility and using as base material the nearer included in the Material Database ( I think is the silicon-nitride ) and fitting it to keep near to the desired value.
Is it right?
For nonlinear analysis, I want to ask how I can make sure to launch very high power values (like 10 W or 100 W) because it is not clear how to modify the source amplitude to make sure of doing an analysis for different high power values.
Thank you in advance.