Learning Forum

[Saha]

I need to check response of a dielectric film considering only third order nonlinearity. It seems there is two way to define it.
1)chi3/chi2 material --> only chi3 has nonzero value (e.g. 1e-19) and base material is defined seperately with a (n,k) material with n=4,k=0 (no loss);

2)kerr nonlinear --> permittivity =16, chi3= 1e-19.

As I ran the 2D sim with a plane wave source and sweeped the amplitude (E0), the T response was different. Here is a plot for a film thickness of 125nm.

Can anyone help me understand the difference in dynamics of these two material types? Thanks.

[Guilin Sun]

Those two models do not apply for the same material, as chi2/chi3 model needs non-zero chi2. If it is pure chi3, please use the chi3 material-Kerr model only.  Example can be found here  https://optics.ansys.com/hc/en-us/articles/360041718634-Kerr-effect-on-Gaussian-beam-propagation

 

[Saha]

Thanks for clarification. 

The built in kerr nonlinear model seems to take input for only single permittivity value.  Can this be applied for dispersive materials as well? If so, how?

[Guilin Sun]

It seems no. Please refer this page https://optics.ansys.com/hc/en-us/articles/360034394734-Advanced-and-custom-optical-material-models-in-FDTD-and-MODE